Problem:
Attempting to run the adaptive TIN ground filter on a Dense Image Matching (DIM) point cloud does not classify any points.
Probable Resolution #1:
When a point cloud is created from a Dense Image Matching process, the resulting LAS produced by some software is not classified (0) and has 0 of 0 returns. Identifying points in LP360 will show “0 of 0” under Returns. The LAS format expects a Return Number of 1 and higher. The default adaptive TIN ground filter in LP360 filters to last return points, such as 1 of 1, 2 of 2, 3of 3, etc. Hence, 0 of 0 points will be filtered out. To fix the errant points use the LP360 LAS File Analyst repair utility.
- Add the LAS files into LP360 as open for Read/Write
- Select “LAS File Analyst” by right-clicking the LAS layer, or clicking the wrench and hammer icon associated with the main LP360 toolbar.
- A dialogue box will appear in which you choose the LAS files for repair.
- Open LAS File Analyst Options and select Repair tab. Under the LAS tab, check the box for “Point Return ‘0 of N’.
![](https://fb77ea.p3cdn1.secureserver.net/wp-content/uploads/2019/03/LASfileAnalystOptions.jpg)
5. Select “Repair” button to update all points.
![](https://fb77ea.p3cdn1.secureserver.net/wp-content/uploads/2019/03/LP360ReturnRepairs.jpg)
6. Once the files are repaired, try executing the Adaptive TIN Ground Filter again.
Here are some additional tips on classifying ground with a DIM dataset.