Evaluation of Low-Cost Depth Sensing Cameras for Topographic Mapping

摘要

Topographic surveys provide essential information needed for large-scale mapping for many applications ranging from construction and civil engineering to general purpose mapping. Topographic surveys can be conducted through different means on the ground or remotely. Remotely senseddata are a cost-effective, reliable, and fast source for geospatial data. Recently, the developments in depth (stereo) cameras have opened the door for high-quality and reliable mapping. First of its kind, this study aimed at evaluating the potential of a depth stereo camera (ZED) for topographicmapping. The inexpensive ZED depth camera with its lightweight and portable nature produces a point cloud data file in XYZ format for the surveyed scene. In this study, control points were established in the area with a Topcon GTS-750 total station. Then, a Topcon scanner (GLS 2000M) and a ZED depth camera were both used in the same traverse (at multiple scan stations) to acquire the topography in the form of XYZ coordinates. The points established with the total station were used to co-register the two sets of XYZ coordinates. Furthermore, 20 ground checkpoints were used to evaluate the topography produced by the ZED camera. The relative accuracy of the ZED camera points compared with that of the laser scanner resulted in RMSE of 1 cm (±0.3 cm) horizontally and 11.1 cm (±3.3 cm) vertically at 95 percent confidence interval. Thislevel of accuracy meets the US National Map standards as well as the USGS(1996) and ASPRS (1990) map accuracy standards for large-scale mapping. Accordingly, the ZED camera can be used to reliably produce 0.61-m (2-foot) contour maps at a mapping scale of 1:2,000 or smaller, which are suitablefor general purpose large-scale mapping but not for construction and civil engineering applications.