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The term "Masking" in ArcGIS

June 05 2008 | 1 comment

I routinely create vector masks in Adobe Illustrator and was trying to do a similar technique in ArcGIS by invoking the Advanced Drawing Options. It seems the programmers got something backwards as the masking object becomes masked instead of the other way around.

Probably not the most succinct question - but I can elaborate more if needed.

Mapping Center Answer:

Yes, our language just doesn't have enough words in it, and just to prove it we go and assign new meanings to existing words that mean pretty much the opposite of another of that word's meanings.

Thus, in Adobe Illustrator or Freehand, a mask around an object essentially defines that object's extent and allows you to extract that object or mask the content that surrounds that object.

The masking polygons in ArcGIS are instead more like a knock out, in that they keep something from drawing within the extents of the masking polygon.

We adopted our usage of the term mask from a well known mapping company who described their, at the time, proprietary, procecess for doing what our masking functionality now does. 

Is it a knockout or a mask? posted by Matthew Hampton on Jun 6 2008 2:51PM
I am wondering (from a user perspective) if you might consider using the common vernacular of pretty-much the entire digital vector community and switch to the word usage you used when you described the Advanced Drawing Options (ADO) process to me (i.e. "knock out" instead of "mask").

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