[mapserver-users] Problem loading geotifs

Sat Oct 23 16:51:02 EDT 2010

  I am already using offsite to remove black (0,0,0) from the image.  
But I don't think the problem is not caused by overlaps in the tiles 
because it happens if I only use one tile.

The gdalinfo is:
Driver: GTiff/GeoTIFF
Files: p013r032_7p20001020_z18_nn80.tif
Size is 17480, 15488
Coordinate System is:
PROJCS["WGS 84 / UTM zone 18N",
     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"]],
     PROJECTION["Transverse_Mercator"],
     PARAMETER["latitude_of_origin",0],
     PARAMETER["central_meridian",-75],
     PARAMETER["scale_factor",0.9996],
     PARAMETER["false_easting",500000],
     PARAMETER["false_northing",0],
     UNIT["metre",1,
         AUTHORITY["EPSG","9001"]],
     AUTHORITY["EPSG","32618"]]
Origin = (514189.875000000000000,4576366.125000000000000)
Pixel Size = (14.250000000000000,-14.250000000000000)
Metadata:
   TIFFTAG_XRESOLUTION=72
   TIFFTAG_YRESOLUTION=72
   TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)
   AREA_OR_POINT=Point
Image Structure Metadata:
   INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (  514189.875, 4576366.125)
Lower Left  (  514189.875, 4355662.125)
Upper Right (  763279.875, 4576366.125)
Lower Right (  763279.875, 4355662.125)
Center      (  638734.875, 4466014.125)
Band 1 Block=17480x1 Type=Byte, ColorInterp=Gray

I am tiling by using
gdaltindex to create a shapefile of the tiles using a command similar to 
gdaltindex tile.shp *.tif

The layer definition is
LAYER
   NAME "landsat"
   METADATA
     "wcs_label" "Landsat 7"
     "wcs_rangeset_name" "Range 1"
     "wcs_rangeset_label" "My Label"
   END
   STATUS OFF
   TYPE RASTER
   TILEINDEX "data/Landsat/ETM/band8/subtiles/tindex.shp"
   TILEITEM "LOCATION"
   OFFSITE 0 0 0

   PROJECTION
     # UTM zone 18
     "init=epsg:26918"
   END

   DUMP TRUE
END

I thought the problem might be caused by the size of the tif files, so I 
used gdal_translate to subset the tif files.  I tried it for one landsat 
image.  The result was the same.  The top half of the image renders and 
the bottom half of the image does not.  I tried multiple subset sizes 
ranging from 15x15  which reduces the file size to less than 1% to 1x1 
which is the original size.  The result is that the bottom half of the 
image won't render in Mapserver.

I attached two images of the problem to this email.
error_originalresolution.png  This file shows a single landsat7 geotif 
as downloaded from the USGS archive.  The pixels it is easy to see that 
there is a horizontal line running across the pixel which is not in the 
same coordinate plane as the image.  Offsite is turned on, so the bottom 
half of the pixel renders as transparent.

error_with_subtiles.png  this files shows data from the same landsat7 
image as the prior image.  However, these data were rendered in 
Mapserver by first dividing the original pixel into 15x15 subtiles and 
plotting them.  Only half of each subtile renders.  This leads to a 
banded appearance.

I've also noticed that each time I render the data using Mapserver, the 
affected region is slightly different.

Thanks for the Help!

On 10/23/2010 3:38 PM, Rahkonen Jukka wrote:
> Hi,
>
> My guess is that the data area of your Landsat images are not North-South oriented and they have triangular no-data areas in the corners.  Adjacent images are overlapping when you view them together and no-data area from one image is covering the real data of the image underneath. The cure is to use OFFSITE in the mapfile to tell what pixel value should be made transparent. No-data value is often stored in the geotiff metadata and you can check it with gdalinfo. Perhaps most often it is all black (0 0 0). But this is just a guess and if I did not hit, please
> - send a gdalinfo report of one image
> - send the command you used for tiling
> - send the LAYER definition you have used in the mapfile
>
> -Jukka Rahkonen-
>
>
> -----Alkuperäinen viesti-----
> Lähettäjä: mapserver-users-bounces at lists.osgeo.org puolesta: ecodavid at rci.rutgers.edu
> Lähetetty: la 23.10.2010 21:04
> Vastaanottaja: mapserver-users at lists.osgeo.org
> Aihe: [mapserver-users] Problem loading geotifs
>
> I am trying to add Landsat7 images to my mapserver project.  I have
> downloaded the images in geotif format from the USGS.  These images
> correspond to a rectangular snapshot over the region.  Since multiple
> geotiffs are needed to cover my region, I am tiling the images using gdal.
>
> Here is the problem I am having: The geotiffs render only partially.  For
> example, the top half of the image will render, and the bottom half will
> not.  I have opened the geotiff files in several image editors and can
> view the entire region, so I am assuming that the problem is somewhere in
> the Mapserver rendering.  Also, I have tried inserting the image directly
> (i.e. not using tiling) and get the same result.
>
> Can anyone help me out?
> _______________________________________________
> mapserver-users mailing list
> mapserver-users at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/mapserver-users
>
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