[mapserver-users] Some queries return blank Images

[EdouardG]

First, thank you for this quick answer. I have been struggling quite a bit
with this.

I agree with you on the projection problem, the error made me think that at
first. The problem is all my data is in EPSG 4326 and all the request are in
this CRS too. So I would think no reprojection is necessary.

My mapfile is as follow :

MAP
  NAME "Pipes_Angola_WMS"
  EXTENT        11.660069 -7.637100 11.665110 -7.622088

  PROJECTION
    "init=epsg:4326"
  END

  OUTPUTFORMAT
    NAME "GTiff"
    DRIVER GDAL/GTiff
    MIMETYPE "image/tiff"
    IMAGEMODE RGB
    EXTENSION "tif"
  END
  
  CONFIG "MS_ERRORFILE" "/data_local/mapdata/ms_error.txt"

  WEB
  METADATA
   "wms_title"           	"Pipes Angola Server"
   "wms_onlineresource"  	"http://10.57.168.114/wms"
   "wms_srs"             	"EPSG:4326"
   "wms_enable_request" 	"*"
  END
  END

  LAYER
    NAME "Pipes_Layer"
    STATUS ON
    TYPE RASTER
    DEBUG 5
    TILEINDEX "/data_local/mapdata/data/index.shp"
    TILEITEM "location"
    METADATA
      "wms_title"    	"WMS Pipe Angola"
      "wms_srs"        	"EPSG:4326"
    END
    PROJECTION
      "init=epsg:4326"
    END

  END

END

The requests I used in my browser where "cutomised" from those I found in
the log made by WolrdWind and Arcmap :

/wms?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetMap&CRS=EPSG:4326&BBOX=-7.6344002188000681,11.660860157323178,-7.6343547473002458,11.660909269398337&WIDTH=1376&HEIGHT=1274&LAYERS=Pipes_Layer&STYLES=&EXCEPTIONS=XML&FORMAT=image/png&BGCOLOR=0xFEFFFF&TRANSPARENT=TRUE 

The result of this request is an image cointaining a working image and a
ghost image also.

I tried gdalinfo on a working and not working image and i got :

for a working image :
Driver: GTiff/GeoTIFF
Files: 20141215-161415.338-026880.tif
Size is 1633, 1431
Coordinate System is:
GEOGCS["WGS 84",
    DATUM["WGS_1984",
        SPHEROID["WGS 84",6378137,298.257223563,
            AUTHORITY["EPSG","7030"]],
        AUTHORITY["EPSG","6326"]],
    PRIMEM["Greenwich",0],
    UNIT["degree",0.0174532925199433],
    AUTHORITY["EPSG","4326"]]
Origin = (11.660858092114065,-7.634358707092891)
Pixel Size = (0.000000031665310,-0.000000031665310)
Metadata:
  AREA_OR_POINT=Area
Image Structure Metadata:
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (  11.6608581,  -7.6343587) ( 11d39'39.09"E,  7d38' 3.69"S)
Lower Left  (  11.6608581,  -7.6344040) ( 11d39'39.09"E,  7d38' 3.85"S)
Upper Right (  11.6609098,  -7.6343587) ( 11d39'39.28"E,  7d38' 3.69"S)
Lower Right (  11.6609098,  -7.6344040) ( 11d39'39.28"E,  7d38' 3.85"S)
Center      (  11.6608839,  -7.6343814) ( 11d39'39.18"E,  7d38' 3.77"S)
Band 1 Block=256x256 Type=Byte, ColorInterp=Gray
  Minimum=84.000, Maximum=255.000, Mean=128.986, StdDev=9.596
  NoData Value=0
  Overviews: 817x716, 409x358, 205x179, 103x90, 52x45, 26x23, 13x12
  Metadata:
    STATISTICS_MAXIMUM=255
    STATISTICS_MEAN=128.98649616133
    STATISTICS_MINIMUM=84
    STATISTICS_STDDEV=9.5962094258965


for a not working image :
Driver: GTiff/GeoTIFF
Files: 20141215-161416.853-026881.tif
Size is 1633, 1430
Coordinate System is:
GEOGCS["WGS 84",
    DATUM["WGS_1984",
        SPHEROID["WGS 84",6378137,298.257223563,
            AUTHORITY["EPSG","7030"]],
        AUTHORITY["EPSG","6326"]],
    PRIMEM["Greenwich",0],
    UNIT["degree",0.0174532925199433],
    AUTHORITY["EPSG","4326"]]
Origin = (11.660866469734488,-7.634335714785948)
Pixel Size = (0.000000031279575,-0.000000031279575)
Metadata:
  AREA_OR_POINT=Area
Image Structure Metadata:
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (  11.6608665,  -7.6343357) ( 11d39'39.12"E,  7d38' 3.61"S)
Lower Left  (  11.6608665,  -7.6343804) ( 11d39'39.12"E,  7d38' 3.77"S)
Upper Right (  11.6609175,  -7.6343357) ( 11d39'39.30"E,  7d38' 3.61"S)
Lower Right (  11.6609175,  -7.6343804) ( 11d39'39.30"E,  7d38' 3.77"S)
Center      (  11.6608920,  -7.6343581) ( 11d39'39.21"E,  7d38' 3.69"S)
Band 1 Block=256x256 Type=Byte, ColorInterp=Gray
  Minimum=79.000, Maximum=219.000, Mean=126.598, StdDev=10.897
  NoData Value=0
  Overviews: 817x715, 409x358, 205x179, 103x90, 52x45, 26x23, 13x12
  Metadata:
    STATISTICS_MAXIMUM=219
    STATISTICS_MEAN=126.59779535671
    STATISTICS_MINIMUM=79
    STATISTICS_STDDEV=10.897325852031


The differences are in the pixel size and the dimensions of the image itself
but others with other pixel values and dimensions work perfectly fine.
Mapserver seems to digest those differences for some cases but not for
others...

An otherthing I forgot to tell you is that there is some kind of pattern in
thoses holes. I am supposed to get a coninuous line of pictures overlapping
but the holes are not random, I have something like 5 holes made by
continuous images (which number can be different). But from the survey log,
the two images i pasted the gdalinfo about where taken 1 minute appart...

I hope you have everything you need .



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