TIN generation and point-cloud compression for vehicle-based mobile mapping systems

The vehicle‐based mobile mapping system (MMS) is effective for capturing dense 3D data of roads, roadside objects and buildings. Since discrete points are not convenient for many application systems, a triangulated irregular network (TIN) is often generated from point‐clouds. However, TIN data require two or three times larger storage than point‐clouds. If TIN models can be promptly generated while loading point‐clouds, it would not be necessary to store huge TIN models on a hard disk. In this paper, we propose two efficient TIN generation methods according to types of laser scanners. One is the line‐by‐line TIN generation method, and the other is the GPS‐time based method. These methods can quickly generate TIN models based on scan lines of laser scanners. In addition, we introduce a new compression method to reduce the loading time of point‐clouds. Our compression method is also based on the scan lines of laser scanners. Since points captured by a MMS tend to be positioned on nearly straight lines, their data size can be significantly reduced by coding the second order differences.