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problem of exporting of 300dpi graphic formats with SRTM 90m and hillshading causes color bands

July 18 2008 | 1 comment
Categories: Publishing

I am experiencing rendering problems while exporting a map 300dpi to eps, tiff or pdf formats.
When I have the SRTM 90m and the hillshading (custom stretched hillshading 60 % transparency overdraping the DEM classification 32 classes "ÿellow to brown")the output graphic file 300dpi shows artefacts in the form of different shades of color bands stretching across the map. I have tried different settings (clipped the rasters to AOI map, tried different symbologies-stretching and classification modes - saved the ArcMap project as a different project name, deleted layers as to make the Arcmap project file size smaller). The problem still persists and the bands disappear only when the output resolution is set to 150dpi (which is too low for the publisher requirements).

Your help in this matter greatly appreciated.

Many Thanks,

Luigi

Mapping Center Answer:

I have a couple of suggestions:

First, make sure that both your hillshade and elevation raster layers have their resampling property (on the display tab of layer properties) set to bilinear. That should help diminish the pixelated appearance.

Second, for the banding, this is a known issue with large rasters and there are a couple of workarounds.  These are described in a technical article at our support website.  It looks like the second workaround may work for you.

 

coor bands:classification mode for both of the ras posted by luigi simeone on Jul 18 2008 9:50AM
I have also displayed both of the rasters (DEM and hillshade)in classification mode (32 class). I have then applied the following values to hillshade raster: contrast: 0%; brightness: 20%; trasparency 60%. With this settings the hillshade raster emulate quite well the custom stretch settings I wanted originally and the output 300dpi seems OK.
I will also try the workaround described in the technical article as you suggested.

Many thanks for your help.

Luigi

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