[GRASS-user] interpolating intensity points & r.in.xyz

M S mseibel at gmail.com
Sat May 31 09:55:27 EDT 2008

I have some lidar data, that has return strength or intensity values for an
infrared beam.

the lidar data points have a density to support at least a 3 foot cell size
(thanks to the results of r.in.xzy using meth=n and r.report - a great

Because I'm working with about a 10 square mile area of interest, I found 25
foot cells to work great for watershed delineation based on a time trade off
on larger cells.  Now I want to interpolate the intensity value from lidar
for the 10 sq mile area, starting at a 25 foot cell size, then working down
to smaller cells for greater detail to extract smaller sized features (still
working towards extracting impervious features like roads and houses).  I
suspect the intensity data may be better for house extraction, because the
roofs are mostly all uniform in intensity clusters values, where with RGB
the roof shingles are far to varied for it to classify them cleanly without
other classes of non-roofs appearing all over the map in scattered clusters.

Using r.xyz.in, I am wondering which method is the most appropriate for
getting an intensity value per cell.  Then end result is image
clustering/classification from this data (comparing to the multiband true

Would "method=mean" make the most sense to use to assign intensity values to
the cells with r.in.xyz?
which method of interpolation would be best suited to develop a high
contrast 'intensity' map?

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