[Talk-us] Maine leaf-off imagery?

[Michael Patrick]

 > I see some tutorials for extracting buildings, but I'm interested in
traces of former land-use - finding artificial linear ground features under
the foliage.

I use CloudCompare ( open source ) to good result for lidar point clouds. (
https://www.danielgm.net/cc/ ) ...See
https://drive.google.com/file/d/1h9EmRFOI-WWsQgz3mq9mZ4fuMcDJFfRn/view?usp=sharing
- your mileage may vary, there is a learning curve, but it is a powerful
tool.

That example was made from 'first' return data. If you wanted to get rid of
vegetation, filtering to 'last return' can remove most of it, especially if
your just tracing.
The "Intensity" data does seem to make the sidewalks and pavement pop out
from grass, etc. It might even be possible to distinguish asphalt vs.
concrete, etc. from the signature.
https://drive.google.com/file/d/1unUkJTym-V5SrZDrYA-WYInCKkdo0FrJ/view?usp=sharing

All lidar is not created equal, depending on what reason they flew the
mission ( resolution, flight lines, etc. ). But this is some hangers from
the WA DNR King County Lidar near my house at Renton Field. Certainly
sufficient for tracing:
https://drive.google.com/file/d/1RmWPEQkSrSYi3uRjVn1AjeV3xLDu6Ksy/view?usp=sharing

JOSM seems to have a heart attack when importing more than average size
imagery (understandably ). so you may want to clip your lidar data. Or
trace in a GIS program like Qgis and upload the traces to JOSM.

Michael Patrick,
Data Ferret


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