Geoscience Reference
In-Depth Information
Fig. 15.4
Spatially explicit
representation of the pulse
density
Pulse density
0
10
20
30
40
0
250
500 m
-dx 1 -dy 1
Output grid cell size is 1 by 1 meter (values in output grid cells will represent
density per square meter).
-ot UInt16
Set the data type to UInt16, which can represent the maximum number of pulses
per grid cell.
-o forest_pulse_density.tif
Name of the output raster dataset.
Running statistics on the result (e.g.
gdalinfo -stats forest_pulse
_density.tif
) reports a slightly higher pulse density (16
.
41) than LAStools
(16
36). The calculated mean is positively biased because, by default, the no-data
value is set to 0. Grid cells with a zero value are therefore not taken into account in
the statistics. If we set the grid cell size as
-dx 2 -dy 2
, all grid cells are covered
with points. We then calculate the average point density by dividing the average
number of points per grid cell by 4 (2
.
2m
2
), which exactly matches the result of
×
LAStools (16
.
36).
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