Hi

I'm trying to render some maps using Mapserver that contain both vector and raster data. However the raster data doesn't consistently align with the vector data at different zoom levels.

I've looked at the combination of raster and vector in qgis 11.0 and it displays fine.

When rendering with Mapserver 5.2.0 the raster image positions differently at different zoom levels. I've also recreated the problem using a simple test raster of alternating values which I created programmatically with libgdal.

Does anyone have any suggestions as to what I might be doing wrong or how I might debug my problem further? I'm very doubtful that its a bug in mapserver as surely other people would have encountered this.

I'm using the PROJECTION '+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs' in the map file for both raster and vector

gdalinfo on the test raster:
Driver: GTiff/GeoTIFF
Files: raster/test_qs.tif
Size is 180, 180
Coordinate System is:
GEOGCS["WGS 84",
    DATUM["WGS_1984",
        SPHEROID["WGS 84",6378137,298.2572235629972,
            AUTHORITY["EPSG","7030"]],
        AUTHORITY["EPSG","6326"]],
    PRIMEM["Greenwich",0],
    UNIT["degree",0.0174532925199433],
    AUTHORITY["EPSG","4326"]]
Origin = (-90.000000000000000,90.000000000000000)
Pixel Size = (1.000000000000000,-1.000000000000000)
Metadata:
  AREA_OR_POINT=Area
Image Structure Metadata:
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  ( -90.0000000,  90.0000000) ( 90d 0'0.00"W, 90d 0'0.00"N)
Lower Left  ( -90.0000000, -90.0000000) ( 90d 0'0.00"W, 90d 0'0.00"S)
Upper Right (  90.0000000,  90.0000000) ( 90d 0'0.00"E, 90d 0'0.00"N)
Lower Right (  90.0000000, -90.0000000) ( 90d 0'0.00"E, 90d 0'0.00"S)
Center      (   0.0000000,   0.0000000) (  0d 0'0.01"E,  0d 0'0.01"N)
Band 1 Block=180x45 Type=Byte, ColorInterp=Gray

The shape file prj is...
GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]]

thanks,
Graham
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