Pima County Department of Transportation

Geographic Information Services Division

Developing GIS data for the Web

Automating GIF and CGM files from ARC/INFO

Making GIF (raster) files from ARC/INFO and Generating and viewing CGM (vector) files explain various techniques for making either GIF or CGM files. However, it's nice to make both GIF and CGM files available for web browsing. It's even nicer for us to do this with automated, command line techniques that don't require intervention for each image.

You can make GIF and CGM files from ARC/INFO while you sleep using the technique described here.

• GIF files are created by making a Sun raster file (RAS) and then converting it to GIF format using ImageMagick's convert command.
• CGM files are created by making an Arc graphics file (GRA) and then converting it to CGM format with the Arc cgm command.

This could be done by drawing everything twice with ArcPlot. Sue Fritz found a clever way to save time by using the Map Composition feature. Here's an AML that uses ArcPlot and generates both GIF and CGM files without intervention while only drawing things once in ArcPlot:

/***********************************************************
/* ArcPlot is used to make RAS and GRA files which will 
/* be used to create GIF and CGM files after leaving ArcPlot.
/***********************************************************
arcplot

/***********************************************************
/* Draw to the screen for Sun Raster creation and make a map
/* composition at the same time.  The map composition is 
/* used later to make a GRA file.
/***********************************************************
display 9999 4  /* Display the results on the screen.
map mapname     /* Start a map composition.
   .
   .
/* The "meat" of your ArcPlot drawing aml goes here. 
   .
/* You may need to rearrange the plot order of individual
/* plot elements to be appropriate for screen viewing
/* which does not blend output like most plotters.
/* For instance, lines in a poly must be drawn after
/* poly shading.
   .
   .
mend  /* End the map composition.

/***********************************************************
/* Save the screen image as a Sun Raster (RAS) file.
/***********************************************************
screensave filename.ras  

/***********************************************************
/* Make a GRA file from the saved map composition.
/***********************************************************
display 1040 1    /* Tell ArcPlot to make a GRA file.
                  /* (1 is the default)
filename.gra      
plot mapname      /* Pick up the map composition which 
                  /* will end up in the GRA file defined
                  /* by the above display command.
killmap mapname   /* Delete the map composition.

/***********************************************************
/* Quit ArcPlot.  
/***********************************************************
quit           

/***********************************************************
/* Convert the Sun Raster (RAS) file to GIF with 
/* ImageMagick's convert command.
/***********************************************************
&sys convert filename.ras gif87:filename.gif

/***********************************************************
/* Convert the Arc graphics (GRA) file to CGM with the 
/* Arc cgm command.
/***********************************************************
cgm filename.gra filename.cgm # binary

/***********************************************************
/* Delete the intermediate RAS and GRA files to clean up.
/***********************************************************
&sys rm filename.ras  /* Delete the RAS files. */
&sys rm filename.rsw  /* Delete the RAS files. */
&sys rm filename.gra  /* Delete the GRA file.  */

/***********************************************************
/* End of AML
/***********************************************************
&return