[pdal] Question on filters.assign

[lefsky at gmail.com]

I am working on a voxelization problem and am having difficulty with
filters.assign.
The purpose of the code is to 1) add the HeightAboveGround dimension to
las points using a dtm, copy the Z value of each point to a backup
dimension (PassiveZ), and then calculate a new Z as:

((Z-minx)/scalefactor)+HeightAboveGround


I voxelize the resulting LAS and should get an image of vertical profiles
that includes information about topography and canopy structure, like so:

[image: image.png]

The problem I have is that when I run the JSON for it, I get the
following message:

(pdal_261) lefsky at lefsky-X10DRi:~/time_trials$ pdal pipeline
tile_66_136_sub_01hagscale.json

*PDAL: filters.assign: *

If I remove the filters.assign section, the json runs without a problem.

The Json follows.

I also have another, simpler, problem involving the extra_dims keyword for
writers.las. I see the explanation about how to format the specification
for extra_dims (<dimension_name>=<type>) but I couldn't get it to work and
I don't see any examples of proper formatting to follow.

Any help is appreciated.

Michael


{  "pipeline":[
    {"filename":"tile_66_136_sub_01.laz"},
    { "type":"filters.hag_dem","raster":"tile_66_136_dtm.tif"},
{ "type": "filters.assign","value": ["PassiveZ=Z",
            "Z=((PassiveZ-8153)/20)+HeightAboveGround"]},
{       "type":"writers.las",
        "filename":"tile_66_136_sub_01_hagscale.laz",
        "compression":"laszip",
        "extra_dims":"all"}
]}


-- 
Michael Lefsky (He/His)
Home Location: HVHF+GH
Cell: 970-980-9036
http://www.researcherid.com/rid/A-7224-2009

*“for being prematurely, and worse, intuitively right — there’s a heavy
price. But for being wrong — no, not so long as you’re wrong in a pack."
Gary Brecher / Portis*

*I acknowledge that I live and work on stolen land. This is the land of the
Cheyenne, Arapaho, Ute, and Ocheithi Sakowin people. To learn more about
these nations, please visit;
http://www.utemountainutetribe.com/
http://www.cheyennenation.com/
https://cheyenneandarapaho-nsn.gov/
https://native-land.ca/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/pdal/attachments/20240104/9b391abd/attachment-0001.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image.png
Type: image/png
Size: 30545 bytes
Desc: not available
URL: <http://lists.osgeo.org/pipermail/pdal/attachments/20240104/9b391abd/attachment-0001.png>