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We apply quantitative structure modelling to produce detailed information on branch-level metrics in trees. Particularly we are interested in the branch size distribution, by which we mean the total volume of branch parts distributed over the diameter classes of the parts. We investigate the possibility of predicting tree branch size distributions for trees in similar growing conditions. The quantitative structure model enables for the first time the comparisons of structure between a large number of trees. We found that the branch size distribution is similar for trees of different height in similar growing conditions. The results suggest that tree height could be used to estimate branch size distribution in areas with similar growing conditions and topography.

Open geospatial data sources provide opportunities for low cost 3D scene reconstruction. In this study, based on a sparse airborne laser scanning (ALS) point cloud (0.8 points/m2) obtained from open source databases, a building reconstruction pipeline for CAD building models was developed. The pipeline includes voxel-based roof patch segmentation, extraction of the key-points representing the roof patch outline, step edge identification and adjustment, and CAD building model generation. The advantages of our method lie in generating CAD building models without the step of enforcing the edges to be parallel or building regularization. Furthermore, although it has been challenging to use sparse datasets for 3D building reconstruction, our result demonstrates the great potential in such applications. In this paper, we also investigated the applicability of open geospatial datasets for 3D road detection and reconstruction. Road central lines were acquired from an open source 2D topographic database. ALS data were utilized to obtain the height and width of the road. A constrained search method (CSM) was developed for road width detection. The CSM method was conducted by splitting a given road into patches according to height and direction criteria. The road edges were detected patch by patch. The road width was determined by the average distance from the edge points to the central line. As a result, 3D roads were reconstructed from ALS and a topographic database. [ABSTRACT FROM AUTHOR]

We have studied the effect of moisture on the backscatter reflectance of mineral aggregate (such as sand and gravel) targets that are used as reflectance standards in airborne laser scanning intensity calibration. Target moisture has turned out to be a crucial factor when using external reference targets (either commercial or naturally available at the measurement site). The most common targets used thus far are different types of gravel and sand, which emphasizes the role of moisture because of the long time required for drying. We carried out laboratory and field experiments to find out how moisture affects the performance of these targets as reference standards. We found that even small amount of moisture has a crucial effect on target reflectance properties: The backscattered reflectance decreases strongly up to 10% gravimetric water content, after which the reflectance level mostly remains constant. The moisture effect has to be further studied and taken into account in the retrieval and calibration of laser scanner intensity data acquired in moist conditions. We also demonstrate a practical method of deriving the surface backscattered reflectance at different moisture contents with a digital camera. [ABSTRACT FROM AUTHOR]