I was wondering if I could get some advice on a problem I am having with
on-the-fly reprojection of a raster map layer. We are using Mapserver
6.0.0. Our raster images are GeoTiffs. All our source data is EPSG:4326
and we have the WMS set up to support a number of other output
projections, including EPSG:2163 (US National Atlas Equal Area).
However, the image from a GetMap request, when specifying the output
projection of EPSG:2163, gets really pixely/blocky when you are zoomed
in to the western part of Alaska near the international date line.
The image is fine if you are zoomed in to eastern Alaska; the problem
only occurs when the image includes the northern and/or western parts of
Alaska, especially images that get close to the date line and the Arctic
circle.
I tried changing the projection to:
"proj=latlong" "ellps=WGS84" "datum=WGS84" "+over"
on the off chance that it would help, but no luck.
Does anybody have suggestion to help resolve this?
Here is the layer map file.
=======
MAP
OUTPUTFORMAT
NAME "png"
DRIVER AGG/PNG
MIMETYPE "image/png"
IMAGEMODE RGBA
EXTENSION "png"
TRANSPARENT ON
END
OUTPUTFORMAT
NAME "jpeg"
DRIVER AGG/JPEG
MIMETYPE "image/jpeg"
IMAGEMODE RGB
EXTENSION "jpg"
FORMATOPTION "GAMMA=0.75"
END
WEB
METADATA
"wms_onlineresource" "http://<internal_ip_address>/wms?"
"wms_enable_request" "GetMap GetCapabilities GetLegendGraphic"
"wms_title" "Shaded Relief Land - Gray - Alaska Main"
"wms_srs" "CRS:84 EPSG:4326 EPSG:2163 EPSG:102100 EPSG:4269
EPSG:4267 EPSG:54004 EPSG:54008 EPSG:3785 EPSG:3857 EPSG:102113 EPSG:900913"
END
END
IMAGETYPE png
EXTENT -179.9985999 49.8276632 -126.9992066 71.9547724
UNITS METERS
IMAGECOLOR 255 255 254
SIZE 256 256
SHAPEPATH "/home/public_html/map_server/data/raster/"
FONTSET "/home/public_html/map_server/fonts/fonts.list"
SYMBOLSET "/home/public_html/map_server/symbols.sym"
PROJECTION
"init=epsg:4326"
END
LEGEND
STATUS ON
IMAGECOLOR 255 255 255
END
NAME srgy_6arcsec_akmain
LAYER
NAME srgy_6arcsec_akmain
DATA alaska_geo_wgs84_6arcsec_cc_sr_gray_main.tif
STATUS OFF
TYPE RASTER
OFFSITE 0 0 0
METADATA
"wms_title" "Shaded Relief Land - Gray - Alaska Main"
END
END #end the layer
END #end of map
========
Here is the WMS service capabilities map file.
========
MAP
OUTPUTFORMAT
NAME "png"
DRIVER AGG/PNG
MIMETYPE "image/png"
IMAGEMODE RGBA
EXTENSION "png"
TRANSPARENT ON
END
OUTPUTFORMAT
NAME "jpeg"
DRIVER AGG/JPEG
MIMETYPE "image/jpeg"
IMAGEMODE RGB
EXTENSION "jpg"
FORMATOPTION "GAMMA=0.75"
END
WEB
METADATA
"wms_onlineresource" "http://<internal_ip_address>/wms/raster?"
"wms_enable_request" "GetMap GetCapabilities GetLegendGraphic"
"wms_title" "New Projected Raster Data"
"wms_srs" "CRS:84 EPSG:4326 EPSG:2163 EPSG:102100 EPSG:4269
EPSG:4267 EPSG:54004 EPSG:54008 EPSG:3785 EPSG:3857 EPSG:102113 EPSG:900913"
END
END
IMAGETYPE png
EXTENT -179.9985999 49.8276632 -126.9992066 71.9547724
UNITS METERS
IMAGECOLOR 255 255 254
SIZE 256 256
SHAPEPATH "/home/public_html/map_server/data/raster/"
FONTSET "/home/public_html/map_server/fonts/fonts.list"
SYMBOLSET "/home/public_html/map_server/symbols.sym"
PROJECTION
"init=epsg:4326"
END
LEGEND
STATUS ON
IMAGECOLOR 255 255 255
END
NAME raster_test
LAYER
NAME srgy_6arcsec_akmain
DATA alaska_geo_wgs84_6arcsec_cc_sr_gray_main.tif
STATUS OFF
TYPE RASTER
OFFSITE 0 0 0
METADATA
"wms_title" "Shaded Relief Land - Gray - Alaska Main"
END
END #end the layer
END #end of map
======
Any help is greatly appreciated.
Thanks!
-Jennifer Martin
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