[mapserver-users] MapServer returns a blank image when requesting a square image

Seth G sethg at geographika.co.uk
Wed Jan 10 10:55:40 PST 2018


Hi Pablo,

Just to note I also ran into this issue so you are not alone!
A WMS request from OpenLayers to MapServer would be fine, but modifying
the size of the image (WIDTH and HEIGHT parameters) would result in a
blank image and no errors in the logs.I never got a chance to debug further though. An error should ideally be
reported somewhere rather than a blank, seemingly valid, image.
Seth

--
web:http://geographika.co.uk
twitter: @geographika


On Wed, Jan 10, 2018, at 6:46 PM, Pablo Sanfilippo wrote:
> Hi all,
> 
> I admit this is the weirdest issue I have come across. This are the
> relevant parts of my MapServer configuration:> 
> # A valid mapfile used for testing
> MAP
>   NAME valid
>   STATUS ON
>   PROJECTION
>     "init=epsg:4326"
>   END
> 
>   IMAGECOLOR 0 0 0
>   TRANSPARENT ON
> 
>   WEB
>     METADATA
>       "wms_srs"             "EPSG:4326 EPSG:3857"
>   END
>   END
>   
>   LAYER
>     NAME "index"
>     STATUS ON
>     TYPE POLYGON
>     CONNECTIONTYPE POSTGIS
>     CONNECTION "host=x port=x dbname=x user=x password=x"
>     DATA "geometry from (select i.geometry, i.id, '/vsis3/' ||
>     i.s3_bucket || '/' || i.s3_key as location from images_image) as
>     index using unique id">     CLASS
>       STYLE
>         OUTLINECOLOR 0 0 0
>         WIDTH 1.0
>         COLOR 200 200 200
>         ANTIALIAS true
>       END
>     END
>   END
> 
>   LAYER
>     NAME "images"
>     STATUS ON
>     TILEINDEX "index"
>     TILEITEM "location"
>     TYPE RASTER
>     PROJECTION
>       AUTO
>     END
>     METADATA
>       "wms_title"           "Images"
>     END
>   END
>   
> 
> END
> 
> The data in the PostGIS index is in EPSG:4326. The images referenced
> by the index are GeoTIFFs georeferenced in EPSG:4326.> 
> A WMS request for the index layer shows the index polygons fine,
> whatever the SRS and image size in the request.> A WMS request for the images layer using SRS=EPSG:4326 shows the
> images fine, whatever the image size.> A WMS request for the images layer using SRS=EPSG:3857 will work fine
> as long as the requested image size's x is greater than or equal to
> the y. If not, it will return a blank (transparent) image. For
> example, a 1300x1299 image will work fine, a 1300x1300 image won't
> work and 1301x1300 won't work either.> 
> Any clues?
> 
> Thanks!
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> mapserver-users at lists.osgeo.org
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