[Mapserver-users] Large Raster files

[Frank Warmerdam]

mapguy wrote:
> I have a question regarding the relationship between PROJECTION and 
> EXTENT for the display of layers in the mapfile  (mapserve src 4.02 and 
> the new 4.2beta) I have managed to get a custom region working using the 
> mapderve cgi tutorial files as a start. I have successfully displayed 
> and tiled natural color ortho tiffs in EPSG:32115 (NY East state plane), 
> and I have succeeded with a UTM location that displays shape files in 
> EPSG:26918 (UTM 18N NAD83 GRS80).
> 
> I have downloaded 302 world-file-referenced tiffs with the 1:24000 scale 
> topo info for NYS. These are in EPSG:26918 (UTM 18NnAD83 GRS80)  and the 
> extents, coordinate system and mapping have been verified in my GIS 
> program (grass 5.03).  These files will not display, neither as single 
> maps nor as a tiled map, even though the shapefile for the TILEINDEX 
> (with the exact same coord parameters) displays just fine (I even got a 
> county line shapefile map in latlong coordinates to plot properly on the 
> UTM basemap). No errors in the logs.  I used .tfw and .wld and internal 
> GeoTiff (gdal_translated) files all with the same null result.
> 
> I have searched and read the posts on related problems, and it seems I 
> have considered al the possibilities listed. I tried a gdalwarp into 
> state plane (tiff output) coordinates to see if I could "TRANSFORM" it 
> onto the base EPSG:26918 map, but failed to get anything more than the 
> blank map frame.
> 
> Is there something about UTM and EPSG I am missing, at least as they 
> concern mapserver?

Mapguy,

Common problems in this sort of configuration include:
  o Path in the tile index is not absolute.  They don't have to be absolute, but
    it can be tricky to use proper relative paths in a web environment.  If files
    are not found, MapServer will often just quietly ignore the fact.

  o Some sort of mixup with the extents.  Are the extents in UTM 18 as well?
    If the tileindex plots properly this is likely not the problem.

  o Using a MapServer without appropriate format support.  For instance, if you
    don't have GDAL support you may not be able to display some formats of TIFF.

  o Getting the wrong driver.  Old MapServers (4.0? at least in 3.x) sometimes
    would use the built-in TIFF driver instead of GDAL.  The built-in TIFF
    driver only suppose a few variations of TIFF file organization.

My suggestions for debugging:
  o Turn on debugging and review debug messages.  Set the "DEBUG ON" line
    in the MAP object, and in the tileindexed raster layer object.  You should
    see at least a few debug messages even if things are working just fine.

  o Test at the commandline with shp2img program (and debugging enabled).

  o Turn on GDAL debugging when testing with shp2img by setting the environment
    variable GDAL_DEBUG to ON.   You should see debug messages about each TIFF
    file that is actually opened.

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    | Geospatial Programmer for Rent