PROJECT GIGALOPOLIS

This page explains how to import and export SLEUTH image data using ArcInfo Grid.

World File
The world file contains cell size and geographic corner point information for a particular image. It is created when a grid is exported from ArcInfo using the command GRIDIMAGE and can be used import that image, or another image derived from the same, back into Arc using the command IMAGEGRID. It is related to an image by its file name. (e.g.; the world file output.tfw refers to the image file output.tif). The data contained in the world file is general to all grids with the same geographic extent and are therefore transferable between files. See the Arc Docs for more information on world files.

An example:

A grid of urban extent is transformed into a TIFF image as part of processing input data for SLEUTH.

Arc: gridimage urban_data # urban_data.tif TIFF

Two files will be generated from this command: urban_data.tif and urban_data.tfw. The first file is the new TIFF image. The second is the world file and contains geo-reference information.

Now let's say we have a SLEUTH output file that has the same extent as urban_data.tif and we'd like to bring it into a ArcInfo for analysis. SLEUTH uses GIF images as input and generates GIFs as output. Therefore the GIFs first need to be transformed into an ArcInfo friendly image format (such as TIFF) using an image editor software such as xv or Photoshop.

sleuth_output.gif -> sleuth_output.tif

Next the TIFF image can be brought into Arc using the IMAGEGRID command. In order for the image to be geo-registered after the import the a related world file must be in the same directory as the TIFF file being imported.

In a directory:
sleuth_output.tif
sleuth_output.tfw

Arc: imagegrid sleuth_output.tif sleuth_output

Use PROJECTDEFINE to define the new grid's projection.

 

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