Masking Grids

Option on Raster GIS menu.  It is an application of buffering, where you can put a little extra around the geometric shapes you select.

  • Set mask grid--pick a grid to use as the mask.  It must have the same dimensions as the grid to used. You will set the minimum and maximum for the range of values to mask. By default the entire grid will be chosen, but you can use this if parts of the grid have been marked missing with Edit menu.
  • Retain points not meeting criteria: if the points are not in the range you selected, they will be marked missing.
  • Retain points meeting criteria: if the points are in the range you selected, they will be marked missing.

  • Remove missing points in mask: select an open grid, and all missing points in it will be removed from the current grid.

 

Set masking options.

Only points near roads, with buffer of 250 m on each side of the road.  Roads come from the TIGER file, which must have correctly located and indexed.
Only points off roads, with buffer of 250 m on each side of the road.

Additional ways to mask grids:

Mask grid example


Last revision 11/19/2011