[pdal] Raster to points

[Howard Butler]

> On Apr 25, 2019, at 7:29 AM, Steven Spiegel <steven.spiegel at slu.edu> wrote:
> 
> Good morning,
> 
> I have a question about applying rasters to point clouds.  Before I created a TIF, I classified the ground, curvature, height above ground, and normalized intensity.  I then exported it as a tif (resolution = 0.1 m, average, etc) without the ground.  I then combined the three aforementioned attributes and used some image segmentation techniques to separate the objects in the scene.  I now have a labeled raster of my objects (they are not yet classified, just segmented).  Is there a way to then apply a label (as opposed to a class) on the points?  I know you can colorize with a raster or even if I turned it into a shapefile I can then classify that way, but I'm not quite at that level.  I looked through the dimension list  (https://pdal.io/dimensions.html <https://pdal.io/dimensions.html>) and didn't see one that would fit for what I'm looking for.  Can I create a dimension and then apply the label?  If you need further clarification I can provide it.  Thanks!

Steven,

filters.colorization is really just a poorly named filters.overlay for raster

https://pdal.io/stages/filters.colorization.html#filters-colorization <https://pdal.io/stages/filters.colorization.html#filters-colorization>


Something like this might work. Use colorization to grab the first band value and stick it in GPSTime (a dimension of type double that should exist in a default LAS schema). Then copy that over to a dimension called "Segmented". Further processing can use the "Segmented" dimension as needed.

> {
>     "type":"filters.colorization",
>     "dimensions":"GPSTime:1",
>     "raster":"segmented.tif"
> },
> {
>     "type":"filters.ferry",
>     "dimensions":"GPSTime=>Segmented",
> },


Hope this helps,

Howard

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