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Question

Using RGB-values in LAS-files

  • February 13, 2018
  • 2 replies
  • 189 views
M
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Hi all,

I'm having a simple question about using the Red-Green-Blue (RGB-) values from point clouds. I have a LAS-file, which is already coloured and does display the RGB-values when I open the LAS-file in the FME Data Inspector.

However, it seems impossible to use those values in any kind of calculator. I have a GIS-background, and I am used to a strict vector/raster data separation. It seems like a LAS-file is read as a raster, although it can contain multiple points per [xy]-value (e.g. walls, tree stems).

I want to use the RGB-values that are already in de point properties. I see how I can keep them (e.g. PointCloudPropertyExtractor), but there seems to be no way to use these properties in any kind of calculation tool.

The reason why I want to do this, is because I want to filter some points out based upon the ratio (R+G)/B.

Suggestions are welcome :)

Thanks in advance,

Martin

2 replies

takashi
Influencer
  • takashiInfluencer
  • February 13, 2018

Hi @martin_fme, I think you can use the PointCloudExpressionEvaluator to add a new component that stores the valud of (R+G)/B for every point to the point cloud feature. e.g.

Expression:

(@Component(color_red)+@Component(color_green))/@Component(color_blue)

0684Q00000ArKbaQAF.png

M
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  • martin_fme
  • Author
  • February 15, 2018

Hi @takashi, thank you very much for your answer! I tried it, and it worked! After using the PointCloudExpressionEvaluator, I used the PointCloudFilter to filter the points based upon the output of the PointCloudExpressionEvaluator.

 

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