Coordinate transformation error when creating point cloud from .laz

Grasshopper
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1

I am experiencing some issues with the Heron when transforming from UTM zone 11N (EPSG:26911) to NAD83 / California zone 6 (ftUS) EPSG:2230

Either I am making an error or there is a glitch in the Heron plugin. It appears that the X and Y coordinates of each point in the .laz file are correct, but z coordinates appear be incorrect. Points appear to be scale 1D’d in the Z axis by a factor around 1/3 which leads me to believe that Z coordinates remained in meters somehow.

Please let me know if I am using the plugin incorrectly or if this is an error.

Also interested to know if there is a way to cast the list of output points into a point cloud within grasshopper, baking them and making the point cloud in rhino is very slow.

Thanks!

heronissue.gh (11.9 KB)
.laz: https://rockyweb.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/legacy/CA_ORANGECO_2011/LAZ/USGS_LPC_CA_ORANGECO_2011_000402.laz

2

Hi @grbl9789 ,
I believe the issue lies in the fact that one (or both) of the coordinate systems is not “3D” and GDAL/OGR will only transform the Z component of the point if both coordinate systems are 3D. In this case, you could scale the points in the z direction after they go through CoordinateTransformation.

In the past, I’ve used Cockroach or Volvox to turn the points into a point cloud in grasshopper.

-Brian

3

Thanks! I will try out those plugins.

For future reference would this be the correct place to look to see if it is considered 2D or 3D?:

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4

Yes that could work. Or in the coordinate system definition there would be a third axis defined. The EPSG:4979 used in Evan Rouault’s example in the github issue linked above shows a third axis, which, in my (limited) experience, is not common.

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image1006×1076 93.1 KB

-Brian

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