Ed McNierney wrote:
Frank -
For MapServer EXTENT purposes Benoit will need to adjust the extents by one
whole pixel rather than by half a pixel? If there are N pixels horizontally
measured from the center of the left-hand to the center of the right-hand
pixel, then there are N+1 pixels measured from the left of the left-hand to
the right of the right-hand pixel, rather than N+0.5.
That is, if you adjust all four corners "in" by 0.5 pixel you'll reduce the
height and width by 1 whole pixel each.
Ed,
If the original file is 100 x 100 (for instance) with gdal reported extents
of (0,0) to (1000,1000) then the mapfile should contain:
EXTENT 5 5 995 995
SIZE 100 100
So the size is determined by the SIZE keyword - not the extents.
Note that mapserver macros like MS_CELLSIZE already account for the fact
that the extents represent a region that is in a sense n-1 pixels wide/long.
eg.
#define MS_CELLSIZE(min,max,d) ((max - min)/(d-1))
Best regards,
--
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up | Frank Warmerdam, [EMAIL PROTECTED]
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush | President OSGeo, http://osgeo.org
