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Problem: TIFF images are displayed offset by half a pixel width in ArcMap compared to Workstation ArcInfo

Description

A TIFF image created with GRIDIMAGE or CONVERTIMAGE appears offset half a pixel width down and to the right when displayed in ArcMap.

Cause

GRIDIMAGE and CONVERTIMAGE create GeoTIFF images that don't include raster space information in the image tags.

When an image world file is present, Workstation ArcInfo reads the world file instead of the GeoTIFF tags. The world file default raster space, PixelIsPoint, indicates that the image coordinates are referenced from the center of the upper left pixel.

ArcMap reads the GeoTIFF tags instead of the world file and defaults to the PixelIsArea raster space. This references the image from the upper left corner of the upper left pixel. The difference in the default raster space accounts for the half pixel offset.

Solution or Workaround

There are two methods for creating TIFF images that will not be offset when displayed in ArcMap:

  • At version 9.1, use the Export > Raster To Different Format option in ArcCatalog to generate the TIFF.
  • Use an application that does not create GeoTIFF tags such as Adobe PhotoShop.

    1. Load the image.
    2. Save it as a new TIFF.
    3. Make a copy of the original world file and make the prefix the same as the new TIFF.

    The result will be a TIFF that only has a world file for spatial referencing, and will display correctly in ArcMap.

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