[mapserver-users] rendering a raster crossing the antimeridian through a WMS
Jeff McKenna
jmckenna at gatewaygeomatics.com
Wed Aug 12 10:28:52 PDT 2015
On 2015-08-12 11:43 AM, fred p wrote:
> Thanks to Jeff for the answer.
>
> I simplified the mapfile to make it easier to read.
>
> Below I give the mapfile with these additional elements. I do not have
> warnings anymore with a GetCapabilities request but the image I get
> whith a GetMap request is still incomplete.
>
> Note that I get an error (/msProcessProjection(): Projection library
> error. proj error "projection not named" for ""/) with a projection
> block in the layer section if I declare the real projection definition
> (/"+proj=longlat +a=6378160 +b=6356775 +no_defs "/). No error with
> /"+init=epsg:4326"/ which is closed to the real projection definition.
> As I have read somewhere that if not present the projection is read in
> the data file, I have removed it (the image I get is the same).
>
>
>
> MAP
> STATUS ON
> NAME "foo"
> CONFIG "MS_ERRORFILE" "stderr"
> IMAGETYPE "agg"
> MAXSIZE 8192
> EXTENT -180 -90 180 90
> PROJECTION
> "init=epsg:4326"
> END
> OUTPUTFORMAT
> NAME "agg"
> DRIVER "AGG/PNG"
> MIMETYPE "image/png8"
> IMAGEMODE "PC256"
> EXTENSION "png"
> END
> WEB
> METADATA
> "ows_enable_request" "*"
> "ows_sld_enabled" "true"
> "wms_feature_info_mime_type" "text/html"
> "ows_onlineresource" "http://127.0.0.1:8080/wms"
> "wms_title" "WMS"
> "wms_srs" "epsg:4326"
> END
> END
> LAYER
> STATUS ON
> TYPE RASTER
> NAME "polar_orbiting_avhrr4"
> DATA "/tmp/polar_orbiting_avhrr4.tiff"
> OFFSITE 0 0 0
> PROCESSING "RESAMPLE=NEAREST"
> METADATA
> "wms_title" "foo"
> END
> #PROJECTION
> # "init=epsg:4326"
> #END
> #PROJECTION
> # "+proj=longlat +a=6378160 +b=6356775 +no_defs"
> #END
> END
> END
>
>
Give a good read to the projection page for MapServer
(http://www.mapserver.org/mapfile/projection.html), take note of the
Example#1, how to define the PROJ.4 parameters (I believe your error is
because you've included the "+" by mistake), and then add in your
projection block to your layer. And never assume that MapServer can
magically read your projection and then announce that to all of your WMS
users: always define each layer's actual projection. You can also
experiment with the "PROJECTION AUTO" use, as described on that page,
but I honestly avoid that and set all accurate projection definitions
for each layer.
If this was my situation, I'd test this first without WMS, just with the
shp2img commandline tool, by modifying my output project (see the
"Important Notes" at
http://www.mapserver.org/mapfile/projection.html#important-notes) and
making sure that this layer is reprojected correctly; once that works,
and I'm satisfied with the map image, I'd start testing the WMS
reprojection.
-jeff
--
Jeff McKenna
MapServer Consulting and Training Services
http://www.gatewaygeomatics.com/
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