Surface exports with large void areas such as lakes or other water bodies may require changes to the default export settings. LP360 makes inspections of the neighborhood adjacent to small processing blocks in order to correctly identify the right set of points to triangulate for creating surfaces. This process is called locating the critical surface points (CSP).A set of CSP is a set of points around a rectangular area where no other points added to the surface outside the convex hull created by the CSP's will modify the TIN inside the rectangular area. In order to locate the CSP's for any given rectangular area, a neighborhood must be defined around the area. This is called the thin extent width and height. By default, these values are set to 1000X1000. Meaning that LP360 will increase the rectangular area by 1000X1000 map units in order to search for the CSP's. If water bodies or voids exist in the dataset that are larger than the thin extent width or height critical points could be missed resulting in erroneous surface values across and near the edges of those voids. If you feel that the exported surface shows characteristics of missing critical surface points across void areas, it is suggested that you add breaklines to hold the edge of the water body and/or increase the thin extent width and height settings. Suggested values of thin extent widths and heights can be measured by estimating the largest span across the void areas. How to Setup the Thin Extent Override - Start the registry editor. Start Menu->Run, then type regedit.
- Navigate in the registry editor to HKEY_CURRENT_USER\Software\QCoherent Software\LP360\ for LP360 64-bit or LP360 for ArcGIS on a 32-bit operating system, or HKEY_CURRENT_USER\SOFTWARE\WOW6432Node\QCoherent Software\LP360 32-bit for LP360 for ArcGIS on a 64-bit operating system.
- Right click in the white space to the right, and select 'New', then 'DWORD Value'.
- Type in the name for the new value as 'optThinExtentHeight'.
- Add another 'DWORD value' and call it 'optThinExtentWidth'.
- Right click on one of the new values, and select 'Modify'.
- Select 'Decimal' as the display base.
- Input the correct width if you clicked on optThinExtentWidth, or a correct height if you are editing optThinExtentHeight and select OK.
- Follow the instructions for modifying the other new value.
- Close the registry editor, and restart the LP360 or ArcMap™ if ArcMap is currently running.
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