[mapserver-users] msDrawGDAL query

[Frank Warmerdam]

Rob wrote:
> Apologies if this is a repost - Google mail problems!
> 
> This is my LAYER level output from a Mapscript 4.8.6 install, which 
> results in a blank image appearing with its copyright message.  The 
> missing Context layer is made up of four non-overlapping TIF images, 
> which are indexed via a shapefile.
> 
> [Tue May  6 17:09:09 2008].48097 msDrawRasterLayerLow(Context): entering.
> [Tue May  6 17:09:09 2008].51092 msDrawGDAL(): src=0,0,1050,1950, 
> dst=80,483,1,2
> [Tue May  6 17:09:09 2008].54071 msDrawGDAL(): src=0,0,1050,1950, 
> dst=80,483,1,2
> [Tue May  6 17:09:09 2008].57269 msDrawGDAL(): src=0,0,1050,1950, 
> dst=80,483,1,2
> [Tue May  6 17:09:09 2008].60451 msDrawGDAL(): src=0,0,1050,1950, 
> dst=80,483,1,2
> [Tue May  6 17:09:09 2008].69079 msDrawMap(): Layer 0 (Context), 0.022s
> [Tue May  6 17:09:09 2008].69259 msDrawMap(): Layer 1 
> (CopyrightMessage), 0.000s
> [Tue May  6 17:09:09 2008].165473 msDrawMap(): Drawing Label Cache, 0.096s
> [Tue May  6 17:09:09 2008].165559 msDrawMap() total time: 0.119s
> 
> My query is, do the identical dst values on the msDrawGDAL output lines 
> point to an invalid shapefile for the Context layer? 

Rob,

It is suspicious that the four input files are all treated the same way.
But the output window is 1x2 pixels in size.  I suspect they are all
essentially mapped to a fraction of a pixel, and the 1x2 result in due
to some sort of rounding oddness.

You might want to verify that the tileindex coordinates are really in
the same coordinate system that the layer is declared with in your mapfile.

I suspect a coordinate system problem.

Best regards,
-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org