Raster Meets Point Data - Open Source Geospatial Tools: Applications in Earth Observation - page 139

-sql select_statement
An SQL statement to be evaluated against the datasource to produce a virtual layer
of features to be processed.
-co "NAME=VALUE"
Passes a creation option to the output format driver. Multiple -co options may be
listed. See format specific documentation for legal creation options for each format.

-q

Suppress progress monitor and other non-error output.
src_datasource
Any OGR supported readable datasource.
dst_filename
The GDAL supported output file.

The default behavior of the algorithm is to consider all the points in the input vector
dataset when calculating the value of each grid cell in the output image. You can set
the minimum and maximum points and a search ellipse in which the points must
be found. If less points than min_points are found, the grid cell gets a no-data
value. The algorithm stops searching for new points when it reaches max_points .
Setting the radii of the search ellipse, the algorithm will only use points that are
covered by the ellipse (see the dark colored points in Fig. 10.1 ). The ellipse can also
be rotated, as shown by the angle in Fig. 10.1 . The larger the radii of the search
ellipse, the more points will be taken into account in the interpolation algorithm. To
report some statistics on the points used for the interpolation, some metrics can be
calculated such as: number of points within the search ellipse, minimum, maximum,
range, etc. This is discussed in more detail in Sect. 10.1.2 .
Due to the irregular distribution of the point cloud, it is possible that not all grid
cells (node or pixels) of the output raster file will contain point data. To fill in these
holes with data, the input data must be interpolated. The interpolation algorithm
can be selected from: inverse distance to a power ( invdist ), moving average
( average ) and nearest neighbor ( nearest ). The following options can be set,
each separated by a colon (:). If the options are omitted a default value is selected.

power
Weighting power, only to be used for invdist algorithm (default 2.0).
smoothing
Smoothing parameter, only to be used for invdist algorithm: increases the distance
with this value (default 0.0).
radius1
The first radius (X axis if rotation angle is 0) of search ellipse. Set this parameter
to zero to use whole point array. Default is 0.0.
radius2
The second radius (Yaxis if rotation angle is 0) of search ellipse. Set this parameter
to zero to use whole point array. Default is 0.0.