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arcmaplidarfusionphotogrammetry

Problem to display Vegetation Ratio in Fusion and ArcMap

I'm trying to calculate the vegetation ratio of a forest using point clouds in FUSION. The vegetation ratio is the number of points returned from vegetation (returns from above a certain height, i.e. 2 meters) divided by the total number of returns.

I have 4 different datasets:

  • Lidar from helicopter
  • Lidar from Aircraft
  • Photogrammetry pointcloud, feature-based
  • Photogrammetry pointcloud, Semi-global matching

So: (Number of returns from over 2 m) / (Total number of returns).

I have tried some code in a Fusion Batch, but doesn't seem to get a valid answer.

I just get a gray area when I open it in ArcMap.

    C:\FUSION\Gridmetrix.exe /id:identifier /nointensity /noground /raster:allcover /ascii 2 18 C:OutputFolder\Gridmetrics.csv \InputFolder\PointCloud.las
Solution

  • The Answer to this was simply that the color display was distorted in ArcMap. The calculations were right, however it generated som extreme values which shifted the color scheme stretch. This created a big black/grey square. To fix the problem quickly, one can mask out the outliers using Raster calculator. Allthough, in the long run it's of course better to investigate why these outliers occur. I did not get that far with this project.