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We prove a quantitative estimate, with a power saving error term, for the number of simple closed geodesics of length at most L on a compact surface equipped with a Riemannian metric of negative curvature. The proof relies on the exponential mixing rate for the Teichmüller geodesic flow. [ABSTRACT FROM AUTHOR]

The article presents the results and process analysis of the face milling of aluminium alloy 2017A with the CoroMill 490 tool on an AVIA VMC 800 vertical milling centre. The study analysed the effects of the cutting speed, the feed rate, the actual number of teeth involved in the process, the minimum thickness of the cut layer (hmin), and the relative displacement in the tool-workpiece system D(ξ) on the surface roughness parameter Ra. To measure relative displacement, an original bench was used with an XL-80 laser interferometer. The analysis of relative displacement and surface roughness allowed these factors to be correlated with each other. The purpose of this article is to determine the stable operating ranges of the CoroMill 490-050Q22-08M milling head with respect to the value of the generated relative displacement w during the face-milling process and to determine its influence on surface roughness. The research methodology presented in this paper and the cutting tests carried out allowed the determination of the optimum operating parameters of the CoroMill 490-050Q22-08M tool during the face milling of aluminium alloy 2017A, which are vc 300 m/m and fz—0.14 mm/tooth. Working with the defined cutting parameters allows all the cutting inserts in the tool body to be involved in shaping the geometrical structure of the surface, while maintaining a low vibration level D(ξ) > 1 µm, a low value of the parameter hmin > 1.5 µm, and the desired value of the parameter Ra > 0.2 µm [ABSTRACT FROM AUTHOR]

In this paper, we address the challenge of overcoming the problem of developing doubly curved surfaces in product design. Product design uses two kinds of surfaces, developable surfaces and non- developable surfaces, which are also called singly and doubly curved surfaces, respectively. A developable surface has zero Gaussian curvature at all points, while a non-developable surface has non-zero Gaussian curvature at least in some region. Surfaces of many product design object are commonly created as doubly curved shapes to meet requirements of structure and aesthetic. The problem of creating the planar development of 3D surfaces with double curvature in the product design depends on the shape of the surface and the material of the surface cover. Therefore, the method of deriving a pattern is different when external forces are used in order to generate the plane patterns such as paper strips from the case when the plane shape can stretch or deform to fit on the 3D surface. Given a three-dimensional object surface, the first step of the fabrication process is flattening or planar development of this surface into a planar shape so that the manufacturer can not only determine the initial shape of the object but also estimate the strain distribution required to form the shape depending on a material. The paper is analysing and rationalizing doubly curved surface of a given shape by multiple strips of paper glued onto a surface. Results are addressing possibilities of achieving an overall smooth surface and developing a model for the generation of curvature continuous surfaces composed of paper strip surfaces, as well as generating alternative solutions that are in the domain of contemporary product design. The paper illustrates usability and different variations of the proposed design. [ABSTRACT FROM AUTHOR]

This paper presents a new algorithm for filling holes in Level of Detail 2 (LoD2) building mesh models, addressing the challenges posed by geometric inaccuracies and topological errors. Unlike traditional methods that often alter the original geometric structure or impose stringent input requirements, our approach preserves the integrity of the original model while effectively managing a range of topological errors. The algorithm operates in three distinct phases: (1) pre-processing, which addresses topological errors and identifies pseudo-holes; (2) detecting and extracting complete border rings of holes; and (3) remeshing, aimed at reconstructing the complete geometric surface. Our method demonstrates superior performance compared to related work in filling holes in building mesh models, achieving both uniform local geometry around the holes and structural completeness. Comparative experiments with established methods demonstrate our algorithm's effectiveness in delivering more complete and geometrically consistent hole-filling results, albeit with a slight trade-off in efficiency. The paper also identifies challenges in handling certain complex scenarios and outlines future directions for research, including the pursuit of a comprehensive repair goal for LoD2 models to achieve watertight 2-manifold models with correctly oriented normals. Our source code is available at https://github.com/tudelft3d/Automatic-Repair-of-LoD2-Building-Models.git. [ABSTRACT FROM AUTHOR]

Photogrammetry has gained the interest of professionals and researchers for activities related to construction projects' progress monitoring via attaining precise 3D point models. However, the precision of the generated models is directly linked with the precise scaling of the point cloud to ground truth dimensions (GTDs). Available scaling-up procedures for the close-range photogrammetry technique are complex, time consuming, and require human intervention, which adds the risk of error in the scaled-up model dimensions. Such a scenario creates hesitation among industry professionals toward implementing point cloud technologies. This paper devises an automated scaling-up methodology to overcome the said concerns by considering the construction progress monitoring theme. The intact process of automated scaling up of point cloud model to GTDs is controlled by two main parameters, that is, Python-based modules and designed ArUco-supported controlled markers. Remarkable outcomes are achieved with less than 1% scaled-up error compared with GTDs, which will improve the confidence of industry professionals toward point cloud technologies. Photogrammetry applications have been adopted in several domains and the optimum usage of attained models can be executed with 3D replicas having precise details of surface features and geometry. Therefore, to attain 3D point cloud models with ground truth dimensions (GTDs), or actual dimensions of the targeted object the practitioners mostly follow the markers/ground control points (GCPs) technique (minimum three GCPs/markers), manual scaling, or georeferencing data. However, the accuracy of traditional GCPs/markers' technique and manual rescaling is dependent on the experience of the site staff/operator, and error chances may increase with the increasing number of GCPs/markers, whereas the georeferencing data-based technique is more technical and complex. Therefore, this paper developed an automated system for scaling up 3D point cloud models to GTDs with minimal human involvement. The system works with the help of specialized designed markers known as ArUco-supported controlled markers (ASCM). Only one ASCM marker is placed beside the targeted object for imaging; the devised system detects the marker in the images and rescales the developed point cloud model following the designed strategy. The system has high accuracy and can easily be implemented for scaling up close-range photogrammetry models in any domain. [ABSTRACT FROM AUTHOR]

Soft and biological matter come in a variety of shapes and geometries. When soft surfaces that do not fit into each other due to a mismatch in Gaussian curvatures form an interface, beautiful geometry-induced patterns are known to emerge. In this paper, we study the effect of geometry on the dynamical response of soft surfaces moving relative to each other. Using a simple experimental scheme, we measure friction between a highly bendable thin polymer sheet and a hydrogel substrate. At this soft and low-friction interface, we find a strong dependence of friction on the relative geometry of the two surfaces--a flat sheet experiences significantly larger friction on a spherical substrate than on flat or cylindrical substrate. We show that the stress developed in the sheet due to its geometrically incompatible confinement is responsible for the enhanced friction. This mechanism also leads to a transition in the nature of friction as the sheet radius is increased beyond a critical value. Our finding reveals a hitherto unnoticed mechanism based on an interplay between geometry and elasticity that may influence friction significantly in soft, biological, and nanoscale systems. In particular, it provokes us to reexamine our understanding of phenomena such as the curvature dependence of biological cell mobility. [ABSTRACT FROM AUTHOR]

This paper focuses on the reliability of a synergistic procedure, involving dynamic tests complemented by documentary and architectural research, for the structural assessment of heritage towers. The reliability of the presented method is exemplified in a relevant case study, the Zuccaro's Tower in Mantua. As is known, historic buildings require addressed procedures in order to consider past building transformation and eventual damage/decay, which can affect the masonry properties and, more generally, the structural behavior. The proposed investigation procedure is based on multidisciplinary information (i.e., merging data) from historical and document studies, direct inspections, surveys of geometry and front surfaces, and dynamic tests in operational conditions. The processed information allowed the development and the calibration of a simplified numerical model, useful in driving the seismic/structural assessment of the tower. The results of past investigations, found during the archival research, contributed to the structural evaluation. This paper describes the main research outcomes and the model tuning with a special focus on the key role of the synergy between the applied methods for the assessment of a historic building. [ABSTRACT FROM AUTHOR]

Miniaturization is a dominant trend in machine building which requires the use of advanced techniques of manufacturing and control. Apart from dimensional and shape precision of miniaturized components, surface geometry, particularly roughness and so-called microroughness that results from the use of advanced treatment techniques, plays an important role in correct assembly, reliable operation and durability of the whole machine. The selection of filtration method in surface geometry of micro-objects can be a substantial problem. The authors of the paper propose to use wavelet filtration in digital processing of a point cloud to remove measurement noise and not to change the surface character of the measured object. Also, the authors propose, in this paper, some criteria for selecting the number of wavelet filtration levels based on minimalization of the RMS value. It is supposed to improve the efficiency of low-pass filtration of small areas of the surface, particularly compared to traditional λs Gaussian filtration. [ABSTRACT FROM AUTHOR]

Within the domain of robotic non-destructive testing (NDT) of complex structures, the existing methods typically utilise an offline robot-path-planning strategy. Commonly, for robotic inspection, this will involve full coverage of the component. An NDT probe oriented normal to the component surface is deployed in a raster scan pattern. Here, digital models are used, with the user decomposing complex structures into manageable scan path segments, while carefully avoiding obstacles and other geometric features. This is a manual process that requires a highly skilled robotic operator, often taking several hours or days to refine. This introduces several challenges to NDT, including the need for an accurate model of the component (which, for NDT inspection, is often not available), the requirement of skilled personnel, and careful consideration of both the NDT inspection method and the geometric structure of the component. This paper addresses the specific challenge of scanning complex surfaces by using an automated approach. An algorithm is presented, which is able to learn an efficient scan path by taking into account the dimensional constraints of the footprint of an ultrasonic phased-array probe (a common inspection method for NDT) and the surface geometry. The proposed solution harnesses a digital model of the component, which is decomposed into a series of connected nodes representing the NDT inspection points within the NDT process—this step utilises graph theory. The connections to other nodes are determined using nearest neighbour with KD-Tree optimisation to improve the efficiency of node traversal. This enables a trade-off between simplicity and efficiency. Next, movement restrictions are introduced to allow the robot to navigate the surface of a component in a three-dimensional space, defining obstacles as prohibited areas, explicitly. Our solution entails a two-stage planning process, as follows: a modified three-dimensional flood fill is combined with Dijkstra's shortest path algorithm. The process is repeated iteratively until the entire surface is covered. The efficiency of this proposed approach is evaluated through simulations. The technique presented in this paper provides an improved and automated method for NDT robotic inspection, reducing the requirement of skilled robotic path-planning personnel while ensuring full component coverage. [ABSTRACT FROM AUTHOR]

Verticalization reconfigures plot patterns and private space's relationship with public space at the street level. This paper analyzes eight verticalized neighborhoods in the Santiago Metropolitan Area (SMA) to understand what plot patterns emerge from verticalization and how plot transformation processes affect public space. The empirical research was based on the analysis of plot surface and plot geometry transformations, and of spatial planning urban codes. The study develops quantitative measures and qualitative analysis identifying and presenting four plot transformation categories: (1) Homogenous verticalization through regular plot transformation, (2) Incomplete verticalization through diverse plot configuration, (3) Scattered and intense verticalization, with a partial plot reconfiguration, and (4) Scattered verticalization with changes in plot pattern. The evidence suggests that the plot structure's initial configuration contributes to the urban fabric's consistency and adaptability to verticalization and that urban codes are inconsistent with pre-existing urban form. Plot pattern transformations derived from verticalization unleash significant scale changes in the urban fabric that reconfigure the public–private interface, with greater degrees of enclosure between the plot and the street. [ABSTRACT FROM AUTHOR]

The sliding layer created during operation of the expanded graphite–steel combination has had a huge impact on the effectiveness of the friction process, and thus on the sustainable development of society. Knowledge of the factors determining the properties of the sliding layer will make it possible to reduce friction resistance in the future through the proper design and selection of sliding pairs for given applications. This paper studies the effect of the moisture content of expanded graphite on the formation of a sliding layer on a stainless steel surface. The tests were carried out in static contact for 30 s and dynamic contact for 15 and 30 min, for loads of 10, 20, and 30 N and speeds of 25 and 50 mm/s. To determine the changes in surface geometry due to material transfer, the Ra roughness value of the surface of stainless steel samples was measured. In order to realize the purpose of the work and evaluate the effect of moist rings on the resulting sliding layer, the results of the surface roughness of stainless steel samples working with dry and moist graphite rings were compiled. The obtained results show that the presence of water in the stainless steel-expanded graphite friction node affects the formation of a sliding layer. The resulting layer reduces the surface roughness of the cooperating materials and prevents their accelerated wear. After 5 min of work with the water-soaked graphite counter-sample, depending on the applied friction conditions, a reduction in the surface roughness of the stainless steel sample was achieved in the range of 11–18% compared to the initial value. After 30 min of operation, the surface roughness decreased by 3 to 25%. Pilot studies have shown that operating conditions influence the formation of a sliding layer in the stainless steel-expanded graphite tribological contact. This confirms the validity of conducting further research in this area. [ABSTRACT FROM AUTHOR]

The aim of this paper is to obtain the sub-Riemannian properties of the roto-translation group R T . At the same time, we compute the sub-Riemannian limits of Gaussian curvature associated with two kinds of canonical connections for a C 2 -smooth surface in the roto-translation group away from characteristic points and signed geodesic curvature associated with two kinds of canonical connections for C 2 -smooth curves on surfaces. Based on these results, we obtain a Gauss-Bonnet theorem in the R T . [ABSTRACT FROM AUTHOR]

Reconfigurable intelligent surfaces (RISs) are anticipated to constitute a critical component of forthcoming communication networks due to their ability to establish controllable wireless environments. Furthermore, RIS can be leveraged to solve infeasible localization problems. This paper presents a novel adoption of the geometric dilution of precision (GDoP) analysis in the design of non-line of sight (NLoS) single anchor millimetre wave (mmWave) large RIS-aided localization in the near-field. Considering downlink transmission, the time difference of arrival (TDoA) is used to estimate the positioning by extracting the signal contribution of each RIS tile. Considering the enriched time of arrival (ToA) measurements provided by RIS, the RIS tiles involved in TDoA-based estimation should be selected properly. Therefore, the GDoP adopted in this context is to select RIS tile combinations that achieve minimum GDoP values. It has been shown via numerical simulation that the proposed design of the RIS-aided localization outperforms other state-of-the-art techniques that adopt the signal-to-noise ratio (SNR) for the selection of the RIS tiles. It is demonstrated that the proposed scheme can provide sufficient localization accuracy involving only 10% of RIS tiles, whereas the SNR method requires about (70–80) % of the tiles to approximately achieve the same accuracy. [ABSTRACT FROM AUTHOR]

It is known that the source of a tectonic earthquake in the framework of the theory of elasticity and viscoelasticity is considered to be displacement along a certain fault surface. Usually, when describing a source, the geometry of the fault surface is simplified to a flat rectangular area. The displacement vector is assumed to be constant. In this paper, we propose a model of an earthquake source in the form of a displacement with a constant vector along a stochastic uneven surface. A number of standard assumptions are made during the modeling. We take into account only the elastic properties of the medium. We consider the Earth's crust as a half-space and assume that the medium is homogeneous and isotropic. For the mathematical description of the earthquake source, we use the classical force equivalent of displacement along the fault. This is the distribution of double pairs of forces. The field of displacements under the action of body forces is found through a combination of Mindlin nuclei of strain. The paper presents numerical analytic solutions for displacement along the strike-slip fault corresponding to one of an earthquake source mechanism. We propose to introduce a random deformation of a rectangular flat fault surface. The paper shows the results of a computational experiment comparing the levels and regions of relative deformations of the Earth's crust in the case of displacement along a flat fault surface and along a stochastic uneven one. In the case of a stochastic fault surface, the regions of relative deformations become asymmetric. Such differences from the classical case can be useful for an explanation as to why in some cases the simulation results differ from the results of observations. [ABSTRACT FROM AUTHOR]

In this paper, we study the conchodial surfaces in 3-dimensional Euclidean space with the condition ∆xi = λixi where ∆ denotes the Laplace operator with respect to the first fundamental form. We obtain the classification theorem for these surfaces satisfying under this condition. Furthermore, we have give some special cases for the classification theorem by given the radius function r(u, v) with respect to the parameter u and v. [ABSTRACT FROM AUTHOR]

The velocity and density of a jet resulting from the reflection of a shock wave on a surface with geometric defects (the micro-jetting process) can be an important component of jet fragmentation models. While several models in the literature allow for the calculation of jet velocity, the density is generally ignored. In this paper, we present a semi-analytical method for determining both the velocity and density of a jet from a triangular defect. This model is an extension to micro-jetting specificities of the model usually used for shaped charges. Based on the physics of two-dimensional shocks, it allows a good restitution of the jet velocity and density from classical molecular dynamics simulations. It also provides a good agreement with the literature data, both experimental and numerical. [ABSTRACT FROM AUTHOR]

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3D-printed anodes for bioelectrochemical systems are increasingly being reported. However, comparisons between 3D-printed anodes and their non-3D-printed counterparts with the same material composition are still lacking. In addition, surface roughness parameters that could be correlated with bioelectrochemical performance are rarely determined. To fill these gaps, slurries with identical composition but different mass fractions were processed into SiOC anodes by tape-casting, freeze-casting, or direct-ink writing. The current generation was investigated using electroactive biofilms enriched with Geobacter spp. Freeze-cast anodes showed more surface pores and the highest surface kurtosis of 5.7 ± 0.5, whereas tape-cast and 3D-printed anodes showed a closed surface porosity. 3D-printing was only possible using slurries 85 wt% of mass fraction. The surface pores of the freeze-cast anodes improved bacterial adhesion and resulted in a high initial (first cycle) maximum current density per geometric surface area of 9.2 ± 2.1 A m−2. The larger surface area of the 3D-printed anodes prevented pore clogging and produced the highest current density per geometric surface area of 12.0 ± 1.2 A m−2. The current density values of all anodes are similar when the current density is normalized over the entire geometric surface as determined by CT-scans. This study highlights the role of geometric surface area in normalizing current generation and the need to use more surface roughness parameters to correlate anode properties, bacterial adhesion, and current generation. [ABSTRACT FROM AUTHOR]

This paper proposes a series of experimental determinations carried out with the aim of generating new conclusions regarding the ability of 3D-printed gears to be integrated into mechanisms without lubrication. The main factors that influence the appearance of wear in non-lubricated contact are sliding speed, material hardness, surface finish, surface geometry, and material microstructure. The tests considered the type of material from which they were made and the 3D printing technology type. For testing the gear wheels, a mechatronic experimental setup was made consisting of two shafts with adjustable axial distances, a wheel loading system gears, an electric motor, and a command-and-control system. In terms of materials, four types of materials were monitored: PA (polyamide), PLA (polylactic acid), ABS (acrylonitrile butadiene styrene) and PP (photopolymer). The evaluation of the gear wear was carried out by checking the gearing on two flanks (Frenco ZWP 06) and by scanning with the ATOS CORE 135 3D scanner. The PA and PP gears failed to meet the structural integrity standards after the tests. The PLA gears exhibited superior resistance to abrasive wear compared to the ABS gears, whereas the ABS gears generally demonstrated stronger structural integrity. [ABSTRACT FROM AUTHOR]

Most of the existing point-to-mesh distance query solvers, such as Proximity Query Package (PQP), Embree and Fast Closest Point Query (FCPW), are based on bounding volume hierarchy (BVH). The hierarchical organizational structure enables one to eliminate the vast majority of triangles that do not help find the closest point. In this paper, we develop a totally different algorithmic paradigm, named P2M, to speed up point-to-mesh distance queries. Our original intention is to precompute a KD tree (KDT) of mesh vertices to approximately encode the geometry of a mesh surface containing vertices, edges and faces. However, it is very likely that the closest primitive to the query point is an edge e (resp., a face f), but the KDT reports a mesh vertex υ instead. We call υ an interceptor of e (resp., f). The main contribution of this paper is to invent a simple yet effective interception inspection rule and an efficient flooding interception inspection algorithm for quickly finding out all the interception pairs. Once the KDT and the interception table are precomputed, the query stage proceeds by first searching the KDT and then looking up the interception table to retrieve the closest geometric primitive. Statistics show that our query algorithm runs many times faster than the state-of-the-art solvers. [ABSTRACT FROM AUTHOR]

This paper proposes a method to model masonry shell structures where the shell elements fall into a set of discrete equivalence classes. Such shell structure can reduce the fabrication cost and simplify the physical construction due to reuse of a few template shell elements. Given a freeform surface, our goal is to generate a small set of template shell elements that can be reused to produce a seamless and buildable structure that closely resembles the surface. The major technical challenge in this process is balancing the desire for high reusability of template elements with the need for a seamless and buildable final structure. To address the challenge, we define three error metrics to measure the seamlessness and buildability of shell structures made from discrete equivalence classes and develop a hierarchical cluster-and-optimize approach to generate a small set of template elements that produce a structure closely approximating the surface with low error metrics. We demonstrate the feasibility of our approach on various freeform surfaces and geometric patterns, and validate buildability of our results with four physical prototypes. Code and data of this paper are at https://github.com/Linsanity81/TileableShell. [ABSTRACT FROM AUTHOR]

Ti6Al4V alloy is one of the typical difficult-to-machine materials and often results in rapid tool wear, leading to poor machining quality in aircraft assembling. Compared to conventional helical milling, the ultrasonic assistant helical milling (UAHM) process has indicated its superior performance; however, it is still a great challenge to improve the hole surface quality and accuracy. In addition, few studies have been conducted on the effect of different variables and cooling strategies on the hole-making performance in longitudinal-torsional ultrasonic assisted helical milling (LT-UAHM). This paper, for the first time, reports effects of machining variables on geometric precision and surface roughness in LT-UAHM of Ti6Al4V. In addition, the lubrication/cooling mechanism on the simultaneous application of LT-UAHM and MQL is theoretically analyzed. The design approach of Taguchi experiment was employed to study how major variables such as the cutting speed, tangential feed, axial feed, and the workpiece hardness influence the dimensional and geometrical tolerances and surface roughness. This paper also discussed the effect of three cooling strategies, i.e., dry condition, air coolant, and minimum quantity lubrication (MQL) in LT-UAHM. Theoretical analysis demonstrated that the MQL coolant can be nebulized into hyper-fine droplets owing to the resonant cavitation phenomenon. Combined with the penetrating action caused by the separate-cutting principles of LT-UAHM, the cooling and lubrication performance of MQL was further enhanced. As a result, LT-UAHM with MQL had the most positive effect on circularity, cylindricity, nominal diameter, and surface roughness, contributing to 34%, 32%, 39%, and 40%, respectively. The second important machining factor was the cutting speed, contributing to 31%, 29%, 36%, and 22%, respectively. The tangential feed and workpiece hardness have the negative effect on geometrical accuracy, respectively. [ABSTRACT FROM AUTHOR]

The present study focuses on an up-to-date topic regarding flying equipment identified within the category of drones that use, for propulsion and air movements, the power generated by electric motors. In this paper, researchers focus on implementing bladeless technology to calculate, develop, and construct flying equipment known in the literature as drones. The entire structure of the prototype, all the needed parts, is to be obtained using additive manufacturing technologies, which assumes practical realization using 3D-printing equipment. Nowadays, the 3D-printing process has been proven to be a reliable solution when it comes to manufacturing complex shape parts in quite a short time and with reduced costs. The practical study within the present research aims to obtain polymer-based, lightweight parts with complex shapes inside to be implemented in the propulsion of a drone. The complex surface geometry of the parts that this research used is influenced by the ventilation technology offered by the "Air Multiplier" technology. The entire structure of the final drone equipment, all the parts, is to be manufactured using fused filament fabrication (FFF). The main purpose of the fusion is to use the advantages offered by this technology in drones to obtain advantages such as augmented values of thrust, a more agreeable and muffled sound signature, or an increased level of safety. [ABSTRACT FROM AUTHOR]

In our earlier research (see [Katsanikas & Wiggins, 2021a, 2021b, 2023a, 2023b, 2023c]), we developed two methods for creating dividing surfaces, either based on periodic orbits or two-dimensional generating surfaces. These methods were specifically designed for Hamiltonian systems with three or more degrees of freedom. Our prior work extended these dividing surfaces to more complex structures such as tori or cylinders, all within the energy surface of the Hamiltonian system. In this paper, we introduce a new method for constructing dividing surfaces. This method differs from our previous work in that it is based on 3D surfaces or geometrical objects, rather than periodic orbits or 2D generating surfaces (see [Katsanikas & Wiggins, 2023a]). To explain and showcase the new method and to present the structure of these 3D surfaces, the paper provides examples involving Hamiltonian systems with three degrees of freedom. These examples cover both uncoupled and coupled cases of a quadratic normal form Hamiltonian system. Our current paper is the first in a series of two papers on this subject. This research is likely to be of interest to scholars and researchers in the field of Hamiltonian systems and dynamical systems, as it introduces innovative approaches to constructing dividing surfaces and exploring their applications. [ABSTRACT FROM AUTHOR]

This present study has the purpose of determining how surface topography of implants affects the initial stability of miniscrew implants (MSIs). Electronic databases like PubMed Central, Scopus, Web of Science, Embase, and Cochrane Library, as well as reference lists, were thoroughly searched up until September 2022. Clinical trials involving individuals who got anchorage through mini-implants, along with information on categories of mini-implants dimension, shape, thread design, and insertion site, were required as part of the eligibility criteria. Primary and secondary stability were also assessed. We carried out selection process for the study, extraction of data, quality assessment, and a meta-analysis. The qualitative synthesis included 10 papers: three randomized, four prospective, and four retrospective clinical investigations. The results of this meta-analysis demonstrate that the clinical state of MIs is controlled by their geometrical surface qualities, which are also influenced by their shape and thread design. According to the evidence this meta-analysis produced, this circumstance exists. The duration of the follow-up period and MI success rates did not correlate with one another. [ABSTRACT FROM AUTHOR]

Surface reconstruction using neural networks has proven effective in reconstructing dense 3D surfaces through image-based neural rendering. Nevertheless, current methods are challenging when dealing with the intricate details of large-scale scenes. The high-fidelity reconstruction performance of neural rendering is constrained by the view sparsity and structural complexity of such scenes. In this paper, we present Res-NeuS, a method combining ResNet-50 and neural surface rendering for dense 3D reconstruction. Specifically, we present appearance embeddings: ResNet-50 is used to extract the appearance depth features of an image to further capture more scene details. We interpolate points near the surface and optimize their weights for the accurate localization of 3D surfaces. We introduce photometric consistency and geometric constraints to optimize 3D surfaces and eliminate geometric ambiguity existing in current methods. Finally, we design a 3D geometry automatic sampling to filter out uninteresting areas and reconstruct complex surface details in a coarse-to-fine manner. Comprehensive experiments demonstrate Res-NeuS's superior capability in the reconstruction of 3D surfaces in complex, large-scale scenes, and the harmful distance of the reconstructed 3D model is 0.4 times that of general neural rendering 3D reconstruction methods and 0.6 times that of traditional 3D reconstruction methods. [ABSTRACT FROM AUTHOR]

As consumers increasingly demand more diversified and personalized clothing options, personalized customization has become a hot topic in the garment industry. This study aims to analyze the relationship between the male body shape and block pattern by flattening the prototype surface and conducting quantitative analysis. The study established a three-dimensional box prototype wire frame model on a human body model to obtain the prototype's characteristic size automatically. This enabled the creation of two-dimensional personalized prototypes using surface flattening and the geometric expansion principle. The study also summarized a prototype pattern correction rule by establishing a regression relationship among the human characteristic parameters and the size of the prototype site and the coordinates of the shoulder and back control points. Finally, the correction rule was validated through virtual fitting of a special body model. The result shows that the prototype generated using the flattening method presented in this paper has a high fitness degree and short time consumption and the correction rules can effectively improve the problems of prototype misfit, which can provide an idea and data reference for clothing personalized customization. [ABSTRACT FROM AUTHOR]

Robot workpiece machining is interesting in industry as it offers some advantages, such as higher flexibility in comparison with the conventional approach based on CNC technology. However, in recent years, we have been facing a strong progressive shift to custom-based manufacturing and low-volume/high-mix production, which require a novel approach to automation via the employment of collaborative robotics. However, collaborative robots feature only limited motion capability to provide safety in cooperation with human workers. Thus, it is highly necessary to perform more detailed robot task planning to ensure its feasibility and optimal performance. In this paper, we deal with the problem of studying kinematic robot performance in the case of such manufacturing tasks, where the robot tool is constrained to follow the machining path embedded on the workpiece surface at a prescribed orientation. The presented approach is based on the well-known concept of manipulability, although the latter suffers from physical inconsistency due to mixing different units of linear and angular velocity in a general 6 DOF task case. Therefore, we introduce the workpiece surface constraint in the robot kinematic analysis, which enables an evaluation of its available velocity capability in a reduced dimension space. Such constrained robot kinematics transform the robot's task space to a two-dimensional surface tangent plane, and the manipulability analysis may be limited to the space of linear velocity only. Thus, the problem of physical inconsistency is avoided effectively. We show the theoretical derivation of the proposed method, which was verified by numerical experiments. [ABSTRACT FROM AUTHOR]

This paper presents a study of the total cutting force used and selected parameters of the geometric structure of the surface (e.g., Sa, Sz) during the end milling process of NiTi alloy. The input parameters included are cutting speed (vc), feed per tooth (fz), and radial depth of cut (ae). A Box–Behnken experimental design was employed to conduct the research. The obtained experimental results were utilized within the framework of a response surface methodology (RSM) to develop mathematical and statistical models capable of predicting cutting force components and selected 3D surface parameters. These models provide valuable insights into the relationships between the cutting parameters and the output variables, facilitating the optimization of the NiTi alloy milling process. The findings of this study contribute to a better understanding of the behavior of NiTi alloy during the milling process and offer information for process optimization. By employing a Box–Behnken experimental design, it was possible to investigate the effects of different parameter combinations on the components of total cutting force and selected 3D surface parameters according to ISO 25178, thus aiding in the identification of optimal milling conditions to achieve desired outcomes in the machining of NiTi alloy. [ABSTRACT FROM AUTHOR]

An ultra-narrow precision slit with a width of less than ten micrometers is the key structure of some optical components, but the fabrication of these structures is still very difficult to accomplish. To fabricate these slits, this paper proposed a periodically reducing current over-growth electroforming process. In the periodically reducing current over-growth electroforming, the electric current applied to the electrodeposition process is periodically stepped down rather than being constant. Simulations and experimentation studies were carried out to verify the feasibility of the proposed process, and further optimization of process parameters was implemented experimentally to achieve the desired ultra-narrow precision slits. The current values were: I 1 = I i n i t i a l ,   I 2 = 0. 75 I i n i t i a l   a t   Q c = 0. 5 Q t ,   I 3 = 0. 5 I i n i t i a l   a t   Q c = 0. 75 Q t , r e s p e c t i v e l y.   It was shown that, compared with conventional constant current over-growth electroforming, the proposed process can significantly improve the surface quality and geometrical accuracy of the fabricated slits and can markedly enhance the achievement of the formed ultra-narrow slits. With the proposed process, slits with a width of down to 5 ± 0.1 μm and a surface roughness of less than 62.8 nm can be easily achieved. This can improve the determination sensitivity and linear range of the calibration curves of spectral imagers and food and chemical analysis instruments. Periodically reducing current over-growth electroforming is effective and advantageous in fabricating ultra-narrow precision slits. [ABSTRACT FROM AUTHOR]

The geometric accuracy and surface quality of thin-film cooling holes have a significant impact on the cooling efficiency and fatigue life of aeroengine turbine blades. In this paper, we conducted experimental research on the processing of nickel-based single-crystal high-temperature alloy DD6 flat plates using different femtosecond laser processes. Our focus was on analyzing the effects of various laser parameters on the geometric accuracy results of microholes and the quality of the surfaces and inner walls of these holes. The results demonstrate that femtosecond laser processing has great influence on the geometrical accuracy and surface quality results of film cooling holes. Notably, the average laser power, focus position, and feed volume exert a significant influence on the geometric accuracy results of microholes. For instance, a higher laser power can damage the microhole wall, thereby leading to the formation of tiny holes and cracks. Additionally, microholes exhibit optimal roundness and taper values when using a zero defocus volume. Moreover, increasing the feed distance results in enhanced entrance and exit roundness, whereas scanning speed has a negligible impact on microhole roundness. [ABSTRACT FROM AUTHOR]

Closed-loop manufacturing is crucial in Industry 4.0, since it provides an online detection–correction cycle to optimize the production line by using the live data provided from the product being manufactured. By integrating the inspection system and manufacturing processes, the production line achieves a new level of accuracy and savings on costs. This is far more crucial than only inspecting the finished product as an accepted or rejected part. Modeling the actual surface of the workpiece in production, including the manufacturing errors, enables the potential to process the provided live data and give feedback to production planning. Recently introduced "skin imaging" methodology can generate 2D images as a comprehensive digital twin for geometric deviations on any scanned 3D surface including analytical geometries and sculptured surfaces. Skin-Image has been addressed as a novel methodology for continuous representation of unorganized discrete 3D points, by which the geometric deviation on the surface is shown using image intensity. Skin-Image can be readily used in online surface inspection for automatic and precise 3D defect segmentation and characterization. It also facilitates search-guided sampling strategies. This paper presents the implementation of skin imaging for primary engineering surfaces. The results, supported by several industrial case studies, show high efficiency of skin imaging in providing models of the real manufactured surfaces. [ABSTRACT FROM AUTHOR]

For large bird-like flapping wing aircraft, the fluid–structure coupling problem is very important. Through the passive torsional deformation of the wing, sufficient thrust is generated and propulsion efficiency is ensured. Moreover, spanwise bending deformation will affect lift and thrust. The flow field on the surface of the wing and the geometric nonlinearity caused by the large deformation of the wing should be considered during the design process. Existing research methods do not solve this problem accurately and efficiently. This paper provides a method to analyze the fluid–structure coupling problem of the flapping wing which adopts the three-dimensional unsteady panel method to solve the aerodynamic force, and adopts the linear beam element model combined with the corotational formulation method to consider the geometric nonlinear deformation of the wing beam. This article compares the performance of the flapping wing with different torsional and bending stiffness, and analyzes the airfoil surface pressure coefficients at different portions of the wing during the period. The results show that torsional stiffness has a large influence on the lift coefficient, thrust coefficient and propulsion efficiency. Meanwhile, the torsional stiffness of the wing beam and the initial geometric twist angle of the wing need to be well coordinated to achieve high efficiency. Moreover, appropriate bending stiffness of the wing is conducive to improving propulsion efficiency. [ABSTRACT FROM AUTHOR]

CAD software is a daily tool in ship design offices and shipyards, and every software uses NURBS or B-splines curves and surfaces as common foundations. The CAD tools of today are not static software products and most of them now include parametric design modules, which enable users to change the shape of an object based on its key geometric feature parameters with the use of sliders or equivalent controls. Although B-spline techniques are commonly applied to the representation of the ship hull curves and surfaces, the parametric deformation of the hull surfaces based on geometric parameters is less used. This paper presents a methodology to define the parametric definition of a ship hull with the use of a standard and non-specialized CAD software that is of common use in the ship design offices and universities: Rhinoceros. The presented parametric design methodology will use specific ship hull parameters or feature parameters with a clear geometric meaning, such as displacement, waterplane area, LCB, and LCF, together with the properties of the B-spline curves and the power of Grasshopper, the parametric design tool inside Rhinoceros, to create parametric ship hulls. [ABSTRACT FROM AUTHOR]

The paper presents probabilistic aspects of diagnostics of grinding processes with consideration of metrological aspects of evaluation of topography of machined surfaces and selected problems of assessment of machining accuracy. The processes of creating the geometric structure of the ground surface are described. It was pointed out that the distribution of features important for process diagnostics depends on the mechanism of cumulative effects of random disturbances. Usually, there is a multiplicative mechanism or an additive mechanism of the component vectors of relative displacements of the tool and workpiece. The paper describes a method for determining the classification ability of specific parameters used to evaluate stereometric features of ground surfaces. It is shown that the ability to differentiate the geometric structure of a certain set of surfaces using a selected parameter depends on the geometric mean of the differences in normalized and sorted, consecutive values of this parameter. A methodology is presented for evaluating the ability of various parameters to distinguish different geometric structures of surfaces. Further, on the basis of analyses of a number of grinding processes, a methodology was formulated for proceeding leading to a comprehensive evaluation of machining accuracy and forecasting its results. It was taken into account that in forecasting the accuracy of grinding, it is necessary to determine the deviations, arising under the conditions of multiplicative interaction of the effects of various causes of inaccuracy. Examples are given of processes in which, due to the deformation of the technological system, dependent on the position of the zone and machining force, varying temperature fields and tool wear, the distributions of dimensional deviations are not the realization of stationary processes. It was emphasized that on the basis of the characteristics of the dispersion of the deviation value in the sum set of elements, it is not possible to infer its causes. Only the determination of the "instantaneous" values of the deviation dispersion parameters allows a more complete diagnosis of the process. [ABSTRACT FROM AUTHOR]

The surface voltage of an insulator assumes importance for understanding tracking and flashover characteristics. Until now, determination of surface voltage of insulating surfaces is left to simulation software and such simulations are left unverified experimentally, leading to uncertainty of the results, which may sometimes be erratic with improper choice of boundary or initial conditions or inaccurate material properties, nonlinearities etc. The paper presents a novel method, using which the surface voltage of any insulating surface such as insulator strings or transformer bushings can be measured. Unlike a conducting surface, the measurement of insulating surface voltage using voltage dividers would be erratic as the measuring arrangement itself will vary the voltage division due to the local unknown impedance between the insulated surface and hv conductor. Recently a method for measurement of surface voltage of an insulated conductor using cylindrical strips was reported. In this paper, based on analytical derivations, a more generalized method of measurement, applicable to any point on an insulating surface of arbitrary geometry is proposed using circular-disc strips. The proposed experimental method is applied to insulator strings and transformer bushings and validated by simulation of the entire systems. The simulation and experimental results are in excellent agreement. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a novel method for reconstructing surface normals and depth of dynamic objects in water. Past shape recovery methods have leveraged various visual cues for estimating shape (e.g., depth) or surface normals. Methods that estimate both compute one from the other. We show that these two geometric surface properties can be simultaneously recovered for each pixel when the object is observed underwater. Our key idea is to leverage multi-wavelength near-infrared light absorption along different underwater light paths in conjunction with surface shading. Our method can handle both Lambertian and non-Lambertian surfaces. We derive a principled theory for this surface normals and shape from water method and a practical calibration method for determining its imaging parameters values. By construction, the method can be implemented as a one-shot imaging system. We prototype both an off-line and a video-rate imaging system and demonstrate the effectiveness of the method on a number of real-world static and dynamic objects. The results show that the method can recover intricate surface features that are otherwise inaccessible. [ABSTRACT FROM AUTHOR]

The paper presents the results of research on the surface geometric structure (SGS) of objects made of H13 tool steel reinforced with titanium carbide (TiC) nanoparticles with a concentration between 2.5 and 15% vol., manufactured using the additive manufacturing method (AM) - selective laser melting (SLM). The variable parameters were the percentage of the reinforcing phase and the spatial orientation of the analysed surfaces, while the SLM process parameters were constant. The altitudinal and spatial SGS parameters obtained for the studied samples and surfaces are summarised and compared. The results showed a strong influence of the reinforcing phase content on the values of the surface roughness parameters - with the significant deterioration noted for samples with min. 10% TiC vol. The resulting surface quality was better for upward-facing than downward-facing produced at the same angle. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the use of the Euler characteristic for the topological data analysis, particularly over higher dimensional parameter spaces. The Euler characteristic is a classical, well-understood topological invariant that has appeared in numerous applications, primarily in the context of random fields. The goal of this paper, is to present the extension of using the Euler characteristic in higher dimensional parameter spaces. The topological data analysis of higher dimensional parameter spaces using stronger invariants such as homology, has and continues to be the subject of intense research. However, as important theoretical and computational obstacles remain, the use of the Euler characteristic represents an important intermediary step toward multi-parameter topological data analysis. We show the usefulness of the techniques using generated examples as well as a real world dataset of detecting diabetic retinopathy in retinal images. [ABSTRACT FROM AUTHOR]

Due to its excellent physical properties, γ-TiAl alloy has been widely used in thin-walled components of aerospace engines. However, issues such as low thermal conductivity, poor machinability, and high cutting temperatures often result in difficulties in ensuring the geometric accuracy and surface integrity of the parts. This paper focuses on the study of the thermal deformation behavior of γ-TiAl alloy within a range of higher temperatures and strain rates. Firstly, by conducting quasi-static tests and Hopkinson bar tests on γ-TiAl alloy, the true stress–strain curves of γ-TiAl alloy are obtained within a temperature range of 20~500 °C and a strain rate range of 3000~11,000/s. Based on the Johnson–Cook model, the true stress–strain curves are fitted and analyzed with consideration of the coupling effect of strain rate, temperature, and strain. The strain rate hardening coefficient C and thermal softening exponent m are polynomialized, improving the Johnson–Cook constitutive model of γ-TiAl alloy. The improved model shows significant improvements in the correlation coefficient and absolute errors between the predicted values and experimental values, providing a better reflection of the thermal deformation behavior of γ-TiAl alloy within a range of higher temperatures and strain rates. [ABSTRACT FROM AUTHOR]

The paper presents a novel solution to the issue of incomplete regions in 3D meshes obtained through digitization. Traditional methods for estimating the surface of missing geometry and topology often yield unrealistic outcomes for intricate surfaces. To overcome this limitation, the paper proposes a neural network-based approach that generates points in areas where geometric information is lacking. The method employs 2D inpainting techniques on color images obtained from the original mesh parameterization and curvature values. The network used in this approach can reconstruct the curvature image, which then serves as a reference for generating a polygonal surface that closely resembles the predicted one. The paper's experiments show that the proposed method effectively fills complex holes in 3D surfaces with a high degree of naturalness and detail. This paper improves the previous work in terms of a more in-depth explanation of the different stages of the approach as well as an extended results section with exhaustive experiments. [Display omitted] • We perform 3D surface reconstructions using generative inpainting techniques. • 2D representation of a 3D surface geometry based on its curvature. • Application of a general purpose neural network for inpainting. • Our approach does not require dataset nor training time. • Results outperform state-of-the-art quality and naturalness of the reconstructions. [ABSTRACT FROM AUTHOR]

Noise and lighting are significant factors that have an impact on our health, environment, production quality, etc. The purpose of this paper is to investigate sound and light absorption properties of 3D-printed polyethylene terephthalate glycol (PETG) material specimens that were manufactured with two types of holes, namely with circular and square-shaped holes. In addition, the holes were printed with different dimensions, depths, shapes, and surface spacings. Different factors influencing the material's ability to absorb sound and light were evaluated in this paper. It was found in this study that the type of holes, their spacing and depth have a big influence on sound and light absorption properties of the investigated samples compared to the smooth PETG material. [ABSTRACT FROM AUTHOR]

The paper presents the optimization of process parameters for wood laser engraving based on Taguchi method and analysis of variance (ANOVA). Laser diot mini machines using power source 10W is used for the experimental investigation process. The main parameters in the experimental wood surface laser engraving include such as: laser power (P), engraving speed (S), number of engraving lines per 1mm (L) and engraving head focal height (H). The surface geometrical dimensions while engraving, the engraving width (B) and the engraving depth (D) are main factors to determine the performance of engraving lines and the aesthetics of the product. The experiments were designed by the Taguchi L25 orthogonal array to analyze and obtain the important parameters. Then, to evaluate the optimal combination of parameters in the laser engraving process. The research results show that the influence of the factors P, S takes the leading role. Beside the two parameters L and H have a small influence on wood carving products. The optimization results prove that the combination of above factors at the correct values will give the most optimal set of parameters while maximizing the engraving depth (D) and minimizing the engraving width (B). [ABSTRACT FROM AUTHOR]

The movement of a thin vortex in a thin viscous fluid by the motion of a curve propagating in Lorentz–Minkowski space E 1 3 is described by the vortex filament or smoke ring equation and can be viewed as a dynamical system on the space curves in E 1 3 . This paper investigates the harmonic evolute surfaces of time-like Hasimoto surfaces in E 1 3 . Also, we discuss the geometric properties of these surfaces, namely, we obtain the Gaussian and mean curvatures of the first and second fundamental forms. As a verification, we construct a concrete example for the meant surfaces to demonstrate our theoretical results. [ABSTRACT FROM AUTHOR]

Virtual colonoscopy plays an important role in polyp detection of colorectal cancer. Noise in the colon data acquisition process can result in topological errors during surface reconstruction. Topological denoising can be employed to remove these errors on surfaces for subsequent geometry processing, such as surface simplification and parameterization. Many methods have been proposed for this task. However, many existing methods suffer from failure in computation of all the non-trivial loops, due to high genus or complex topological structures. In this paper, we propose a novel robust topological denoising method for surfaces based on homotopy theory. The proposed method was evaluated on two datasets of colon meshes. We compared our method with the State-of-the-Art persistent-homology-based method. Our method can successfully compute the loops on all colon data for topological denoising, whereas the persistent homology method fails on some colon data. Moreover, our method detects all loops with shorter lengths than those detected by the persistent homology method. Our experimental results show that the proposed method is effective and robust in topological denoising, and that it has the potential for practical application to virtual colonoscopy. [ABSTRACT FROM AUTHOR]

Accurate registration of 3D scans is crucial in creating precise and detailed 3D models for various applications in cultural heritage. The dataset used in this study comprised numerous point clouds collected from different rooms in the Museum of King Jan III's Palace in Warsaw using a structured light scanner. Point clouds from three relatively small rooms at Wilanow Palace: The King's Chinese Cabinet, The King's Wardrobe, and The Queen's Antecabinet exhibit intricate geometric and decorative surfaces with diverse colour and reflective properties. As a result, creating a high-resolution full 3D model require a complex and time-consuming registration process. This process often consists of several steps: data preparation, registering point clouds, final relaxation, and evaluation of the resulting model. Registering two-point clouds is the most fundamental part of this process; therefore, an effective registration workflow capable of precisely registering two-point clouds representing various cultural heritage interiors is proposed in this paper. Fast Adaptive Multimodal Feature Registration (FAMFR) workflow is based on two different handcrafted features, utilising the colour and shape of the object to accurately register point clouds with extensive surface geometry details or geometrically deficient but with rich colour decorations. Furthermore, this work emphasises the challenges associated with high-resolution point clouds registration, providing an overview of various registration techniques ranging from feature-based classic approaches to new ones based on deep learning. A comparison shows that the algorithm explicitly created for this data achieved much better results than traditional feature-based or deep learning methods by at least 35%. [ABSTRACT FROM AUTHOR]

Elements machined by laser and abrasive water jet cutting sometimes require the use of a finishing treatment. One of the finishing methods for machined elements is vibratory shot peening (VSP). This paper presents the influence of VSP technological conditions on the surface topography and surface roughness (parameters Ra and Rsk) of aluminium alloy AW-7075 samples. Experiments were carried out according to the following plan: first, vibratory shot peening (VSP) was conducted using balls with a diameter d = 3 mm, 6 mm and 9 mm. Then, the surfaces of the samples after VSP (treated with 6 mm diameter balls) were subjected to re-vibratory shot peening (RVSP). As a result of vibratory shot peening, the Ra parameter of the specimens after laser cutting decreased by 71% to 91%, while for the AWJ-treated elements it decreased by 56% to 85%. The additional operation decreased the Ra parameter in the entry zone by 4% to 6% for the samples after laser cutting and by 5% to 7% for the samples after AWJ, when compared to the Ra value after single vibratory shot peening conducted using balls with d=6 mm. After VSP and RVSP, the surface topography of the samples changed. Vibratory shot peening led to the creation of "striations" on the shot-peened surface that could not be completely removed. The re-vibratory shot peening operation (for specific conditions) had a positive effect on the geometric structure of the surface of the elements after cutting. Both VSP and RVSP caused reduction in the analysed 3D surface roughness parameters. [ABSTRACT FROM AUTHOR]

Bidirectional reflection distribution function (BRDF) is used to measure colour with gloss and surface geometry. In this paper, we aim to provide a practical way of reproducing the appearance of a 3D printed surface in 2.5D printing of any slope angle and colour in a colour-managed workflow as a means for softproofing. To account for the change in colour due to a change in surface slope, we developed a BRDF interpolation algorithm that adjusts the colour of the tristimulus values of the flat target to predict the corresponding colour on a surface with a slope. These adjusted colours are then used by the interpolated BRDF workflow to finally predict the colour parameters for each pixel with a particular slope. The effectiveness of this algorithm in reducing colour differences in 2.5D printing has been successfully demonstrated. We then finally show how all the components, slope colour adjustment method, interpolated BRDF parameters algorithm, and BRDF model encoded profiles using iccMAX are connected to make a practical appearance reproduction framework for 2.5D printing. [ABSTRACT FROM AUTHOR]

Photometric Stereo (PS) under outdoor illumination remains a challenging, ill-posed problem due to insufficient variability in illumination. Months-long capture sessions are typically used in this setup, with little success on shorter, single-day time intervals. In this paper, we investigate the solution of outdoor PS over a single day, under different weather conditions. First, we investigate the relationship between weather and surface reconstructability in order to understand when natural lighting allows existing PS algorithms to work. Our analysis reveals that partially cloudy days improve the conditioning of the outdoor PS problem while sunny days do not allow the unambiguous recovery of surface normals from photometric cues alone. We demonstrate that calibrated PS algorithms can thus be employed to reconstruct Lambertian surfaces accurately under partially cloudy days. Second, we solve the ambiguity arising in clear days by combining photometric cues with prior knowledge on material properties, local surface geometry and the natural variations in outdoor lighting through a CNN-based, weakly-calibrated PS technique. Given a sequence of outdoor images captured during a single sunny day, our method robustly estimates the scene surface normals with unprecedented quality for the considered scenario. Our approach does not require precise geolocation and significantly outperforms several state-of-the-art methods on images with real lighting, showing that our CNN can combine efficiently learned priors and photometric cues available during a single sunny day. [ABSTRACT FROM AUTHOR]