r.in.[lidar|xyz]: update manual

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@52598 15284696-431f-4ddb-bdfa-cd5b030d7da7

raster/r.in.lidar/r.in.lidar.html

@@ -2,8 +2,13 @@
 
 The <em>r.in.lidar</em> module will load and bin LAS LiDAR point clouds
 into a new raster map. The user may choose from a variety of statistical
-methods in creating the new raster. Gridded data provided as a stream of
-x,y,z points may also be imported.
+methods in creating the new raster.
+<p>
+Please note that the current region extents and resolution are used for 
+the import. It is therefore recommended to first use the <em>-s</em> 
+flag to get the extents of the LiDAR point cloud to be imported, then 
+adjust the current region accordingly and only now proceed with the 
+actual import.
 <p>
 <em>r.in.lidar</em> is designed for processing massive point cloud datasets,
 for example raw LIDAR or sidescan sonar swath data. It has been tested with

raster/r.in.xyz/r.in.xyz.html

@@ -5,6 +5,12 @@ into a new raster map. The user may choose from a variety of statistical
 methods in creating the new raster. Gridded data provided as a stream of
 x,y,z points may also be imported.
 <p>
+Please note that the current region extents and resolution are used for 
+the import. It is therefore recommended to first use the <em>-s</em> 
+flag to get the extents of the input points to be imported, then 
+adjust the current region accordingly and only now proceed with the 
+actual import.
+<p>
 <em>r.in.xyz</em> is designed for processing massive point cloud datasets,
 for example raw LIDAR or sidescan sonar swath data. It has been tested with
 datasets as large as tens of billion of points (705GB in a single file).