Terrain mapping for off-road Autonomous Ground Vehicles using rational B-Spline surfaces and stereo vision

Abstract

Abstract-Autonomous Ground Vehicles designed for extreme environments (e.g mining, constructions, defense, exploration applications) require a reliable estimation of terrain traversability, in terms of both terrain slope and obstacles presence. In this paper we present a new technique to build, in real time and only from a 3D points cloud, a dense terrain elevation map able to: 1) provide slope estimation; 2) provide a reference for segmenting points into terrain's inliers and outliers, to be then used for obstacles detection. The points cloud is first smartly sampled into a 2.5 grid map, then samples are fitted into a rational B-Spline surface by means of re-weighted least square fitting and equalization. To meet an extensive range of extreme off-road scenarios, no assumptions on vehicle pose are made and no road infrastructure or a-priori knowledge about terrain appearance and shape is required. The algorithm runs in real time; it has been tested on one of VisLab's AGVs using a modified SGM-based stereo system as 3D data source.

Implementation of an open platform for 3D spatial information based on WebGL

“…The corner is a 3D vector based on the XDO coordinate system, as shown in Figure . In the case of back‐face culling, if the angle between the corner point and the camera is less than 90°, the target is a rendering target and is in the front .…”

Terrain Roughness Identification for High-Speed UGVs

“…For example the work in [24] presented a method of estimating the terrain slope. This approach serves a different purpose to the RI presented in this paper; it can be used to determine the stability of the UGV as it traverses terrain.…”

“…An example of a geometric technique that does address the level of traversability is an approach by Broggi et al that provides a method for detecting the slope of the terrain, as well as obstacle detection, through fitting a terrain to a B-spline surface [24]. This slope estimation provides an explicit geometric measure of the terrain which is useful as a traversability metric for preventing occurrences such as rollovers.…”

Traversability analysis using terrain mapping and online-trained Terrain type classifier

“…This map is built from the disparity space of the stereo image; the resulting 3D points in the space are used to generate a surface model of the terrain. Finally, the surface slope, the elevation of the cell and the obstacles in the cell neighborhood are used to define the cost for each cell [7] [2]. The Fig.…”