17 research outputs found
An Automatic Digital Terrain Generation Technique for Terrestrial Sensing and Virtual Reality Applications
The identification and modeling of the terrain from point cloud data is an
important component of Terrestrial Remote Sensing (TRS) applications. The main
focus in terrain modeling is capturing details of complex geological features
of landforms. Traditional terrain modeling approaches rely on the user to exert
control over terrain features. However, relying on the user input to manually
develop the digital terrain becomes intractable when considering the amount of
data generated by new remote sensing systems capable of producing massive
aerial and ground-based point clouds from scanned environments. This article
provides a novel terrain modeling technique capable of automatically generating
accurate and physically realistic Digital Terrain Models (DTM) from a variety
of point cloud data. The proposed method runs efficiently on large-scale point
cloud data with real-time performance over large segments of terrestrial
landforms. Moreover, generated digital models are designed to effectively
render within a Virtual Reality (VR) environment in real time. The paper
concludes with an in-depth discussion of possible research directions and
outstanding technical and scientific challenges to improve the proposed
approach
DETECTION OF PLANAR POINTS FOR BUILDING EXTRACTION FROM LIDAR DATA BASED ON DIFFERENTIAL MORPHOLOGICAL AND ATTRIBUTE PROFILES
This paper considers a new method for building-extraction from LiDAR data. This method uses multi-scale levelling schema or
MSLS-segmentation based on differential morphological profiles for removing non-building points from LiDAR data during the data
denoising step. A new morphological algorithm is proposed for the detection of flat regions and obtaining a set of building-candidates.
This binarisation step is made by using differential attribute profiles based on the sum of the second-order morphological gradients. Any
distinction between flat and rough surfaces is achieved by area-opening, as applied within each attribute-zone. Thus, the detection of
the flat regions is essentially based on the average gradient contained within a region, whilst avoiding subtractive filtering rule. Finally,
the shapes of the flat-regions are considered during the building-recognition step. A binary shape-compactness attribute opening is
used for this purpose. The efficiency of the proposed method was demonstrated on three test LiDAR datasets containing buildings
of different sizes, shapes, and structures. As shown by the experiments, the average quality of the buildings-extraction was more than
95 %, with 96 % correctness, and 98 % completeness. In terms of quality, this method is comparable with TerraScan®, but both methods
significantly differ when comparing correctness and completeness of the results
Rapport sur le comparatif des méthodes de détection d'arbre
In the presented study established single tree detection methods are benchmarked and investigated. In total eight airborne laser scanning (ALS) based detection methods were applied to a unique dataset originating from different regions of the Alpine Space covering different study areas, forest types and structures. The evaluation of the detection results was carried out in a clear and reproducible way by automatically matching the detection results to precise in-situ forest inventory data. Quantitative statistical parameters such as the percentages of correctly matched trees and omission and commission errors are presented. The benchmarking results are prepared in complementary levels of information, starting with the analysis based on study area as well as detection method. Additionally investigations per forest type and an overall performance of the benchmark are presented. The best matching rate was obtained for single layered coniferous forests. Trees in lower height layers were challenging for all tested methods. The overall performance shows a matching rate of 47% which is comparable to results of other benchmarks performed in the past for other forest types. The study brings new hindsight regarding the potential and limits of tree detection with ALS and underlines some key aspects regarding the choice of method when performing single tree detection for the various forest types encountered in alpine regions