msResampleGDALToMap(): fix inappropriate cellsize computation when lo…

…ading (well beyond) full source raster.

mapresample.c

@@ -1471,7 +1471,12 @@ int msResampleGDALToMap( mapObj *map, layerObj *layer, imageObj *image,
     sqrt(adfSrcGeoTransform[1] * adfSrcGeoTransform[1]
          + adfSrcGeoTransform[2] * adfSrcGeoTransform[2]);
 
-  if( (sOrigSrcExtent.maxx - sOrigSrcExtent.minx) > dfOversampleRatio * nDstXSize
+  /* Check first that the requested extent is not greater than the source */
+  /* raster. This might be the case for example if asking to visualize */
+  /* -180,-89,180,90 in EPSG:4326 from a raster in Arctic Polar Stereographic */
+  if( !(sOrigSrcExtent.minx <= 0 && sOrigSrcExtent.miny <= 0 &&
+        sOrigSrcExtent.maxx >= nSrcXSize && sOrigSrcExtent.maxy >= nSrcYSize)
+      && (sOrigSrcExtent.maxx - sOrigSrcExtent.minx) > dfOversampleRatio * nDstXSize
       && !CSLFetchBoolean( layer->processing, "LOAD_FULL_RES_IMAGE", FALSE ))
     sDummyMap.cellsize =
       (dfNominalCellSize * (sOrigSrcExtent.maxx - sOrigSrcExtent.minx))

msautotest/wxs/wms_polar_stereo.map

@@ -0,0 +1,48 @@
+#
+# Tests support for images in polar stereographic projection
+#
+# REQUIRES: SUPPORTS=WMS
+#
+#
+# GetMap
+# RUN_PARMS: wms_polar_stereo.png [MAPSERV] QUERY_STRING="map=[MAPFILE]&SERVICE=WMS&VERSION=1.3.0&REQUEST=GetMap&LAYERS=test&STYLES=&CRS=EPSG:4326&BBOX=-89,-180,90,180&WIDTH=200&HEIGHT=200&FORMAT=image/png" > [RESULT_DEMIME]
+
+MAP
+
+NAME TEST
+STATUS ON
+SIZE 200 200
+EXTENT -180 -89 180 90
+IMAGECOLOR 0 0 0
+
+PROJECTION
+  "init=epsg:4326"
+END
+
+IMAGETYPE png8_t
+
+OUTPUTFORMAT
+  NAME png8_t
+  DRIVER "GD/PNG"
+  IMAGEMODE PC256
+  TRANSPARENT OFF
+END
+
+WEB
+  METADATA
+    "ows_enable_request" "*"
+    "wms_srs" "EPSG:4326"
+  END
+END
+
+LAYER
+  NAME test
+  TYPE raster
+  STATUS default
+  DATA data/polar_stereo.tif
+  PROJECTION
+    AUTO
+  END
+END
+END # of map file
+