WARNING: Idrisi's definition of a projection may not exactly match that of ARC/INFO or ArcView. Be sure to compare false eastings, scale factors, etc. A difference in a scale factor of .00003333 may mean a 60 foot shift or more when laying vector data over the image. Also, the projection engine used by ARC/INFO and ArcView is not identical that used by Idrisi; in most cases, however, the difference should not be more than 0.5 meters.

Displaying Idrisi Images in ArcView

If you're using ArcView Version 3.1 or greater, you may display Idrisi images directly using the AVIdris extension. For more information, click HERE.

Exporting Idrisi Images to ArcView

There are two basic export options: ERDAS and TIFF. ERDAS format may be exported in one step, but cannot be compressed and requires setting up a colormap in ArcView. TIFF format may be compressed and requires no colormap, but exporting and georeferencing is a two-step process. Of the two formats, ArcView seems to print TIFF much more efficiently.

Exporting to ERDAS

1) Use ERDIDRIS to export the image to a .GIS file.

MACRO Example:

   ERDIDRIS x 3 drg drg.gis
2) Use PALETTE WORKSHOP to export the palette (.SMP) to a .PAL file (no Macro command available).

3) In ArcView, run the script View.LoadGIS to load the image as a theme and assign color values from the .PAL file.

USGS Digital Raster Graphic (DRG) images use a standard palette. The script View.LoadDRG will load the image as a theme in ArcView and assign the standard DRG palette without need to create a .PAL file.

Exporting to TIFF

1) Use TIFIDRIS to export the image to a .TIF file, specifying the name of the palette to be used.

MACRO Example:

   TIFIDRIS x 2 drg drg 90 drg
2) Create a world file (.TFW) containing the georeferencing information. The program WORLD.EXE, executable from the MS-DOS prompt, reads the document file of the image and generates the appropriate world file. For example:

   world drg drg
3) [Optional, highly recommended] If compression is desired, use a third-party program (e.g. Corel Photo-Paint or Image Alchemy) to convert the image to TIFF with packbit compression. ArcView handles packbit compressed TIFF images much more efficiently than uncompressed.

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