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Automatic generation of reliefs from 3D objects has received great attention in the past few years. The existing methods, which have been developed for general relief generation, are not suitable to handle portrait models that have distinct geometrical features. In this paper, we present a novel method for portrait relief modeling which takes mesh deformation as the theoretical basis. In a pre-processing stage, we segment the input model into several meaningful regions so that different portrait regions could be separately processed. To emphasize visually important features, we further compute object saliency and apply normal enhancement. Once the projective direction is selected by users, the input object is transformed into a compressed height field, followed by a Laplacian-based mesh deformation to optimize the height field. The fine details, salient features and depth structures could be well constructed in the final relief. Experiments and comparisons with state-of-the-art methods demonstrate the effectiveness of our method.

We introduce a normal-based modeling framework for bas-relief generation and stylization which is motivated by the recent advancement in this topic. Creating bas-relief from normal images has successfully facilitated bas-relief modeling in image space. However, the use of normal images in previous work is restricted to the cut-and-paste or blending operations of layers. These operations simply treat a normal vector as a pixel of a general color image. This paper is intended to extend normal-based methods by processing the normal image from a geometric perspective. Our method can not only generate a new normal image by combining various frequencies of existing normal images and details transferring, but also build bas-reliefs from a single RGB image and its edge-based sketch lines. In addition, we introduce an auxiliary function to represent a smooth base surface or generate a layered global shape. To integrate above considerations into our framework, we formulate the bas-relief generation as a variational problem which can be solved by a screened Poisson equation. One important advantage of our method is that it can generate more styles than previous methods and thus it expands the bas-relief shape space. We experimented our method on a range of normal images and it compares favorably to other popular classic and state-of-the-art methods.

Sunken relief is an art form made by cutting the relief sculpture itself into a flat surface with a shallow overall depth. This paper focuses on the problem of direct generation of line-based sunken relief from a 3D mesh. We show how to extract, post-process and organize the messy feature lines in regular forms, applicable for lines engraving on the sculpture surfaces. We further describe how to construct a smooth height field from the input object, and derive a continuous pitting corrosion method to generate the cutting paths. The whole framework is conducted in object-space, making it flexible for stroke stylization and depth control of the engraving lines. We demonstrate the results with several impressive renderings and photographs used to illustrate the paper itself.