Automatic Terrain Extraction
Introduction This chapter tells you about the elevation extraction capabilities of Leica Photogrammetry Suite (LPS) Automatic Terrain Extraction (ATE). LPS ATE provides a variety of options and parameter settings.
Product Workflow The workflow associated with extracting DTMs can be categorized as being either noninteractive or interactive. The noninteractive mode is suited for large-scale DTM production, where minimal interaction and input is needed to extract a DTM for an entire geographic area covered by a block of images. The interactive mode allows you to select the image pairs, define DTM properties, digitize areas of interest, and specify 3D reference information for subsequent accuracy calculations. As a result, LPS ATE provides a scalable 3D mapping solution for both novice and experienced mapping professionals alike. The following product workflow can be used to extract DTMs using LPS ATE:
1. In LPS Project Manager, create a block project; add images; define the camera/sensor model; measure ground control, tie, and check points; and perform automatic tie point collection and block triangulation. In order to automatically extract DTMs, the block triangulation results must be accepted or fixed.
2. Select the DTM Extraction icon from the LPS Project Manager toolbar. General DTM extraction properties can be defined for subsequent DTM production. General options include:
• Output DTM Type (ASCII, TerraModel TIN, SOCET SET TIN, DEM, 3D Shape)
• Output a single mosaicked DTM for the entire project or individual DTMs for each image pair in the project
• Output DTM name (for a single DTM) or DTM prefix (for multiple DTMs)
• DTM Cell Size in the X and Y direction
• DTM Trim percentage which automatically subsets each DTM once it has been extracted
Selecting Run begins the extraction process. Selecting Advanced Properties allows you to interactively select additional DTM extraction properties.