Deriving Roadless & Padless Areas

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08-31-2011 02:30 PM
ABDALLAMOHAMED
Occasional Contributor
Hello..I have two shapefiles:- roads which are  polylines , and pads which are polygons. I was trying to derive the roadless and padless areas
  from the total study area, and don't know  what is the appropriate tool to use. Any hint, I really appreciated.
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4 Replies
DarrenWiens2
MVP Honored Contributor
If you have an ArcInfo license, use the Erase tool (buffer the roads first, so they are polygons). If you don't have ArcInfo, you can Dissolve all of your roads (or pads) together into one shape and simply subtract the area number from the total area.
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ABDALLAMOHAMED
Occasional Contributor
Hi Darren..Thanks for your help, but the Dissolve tool won't combined both shapefiles together into one shape..You have to do them one at the time and that has no value..What I'm looking for is the combined  area of road and pad so that I can subtract it from the total study area..So what did I  buffered the roads(5 meters buffer) and then calculated the total area ofthe buffered roads and pads separately, added them together and subtracted from the total study area..The result is the total  for roadless and padless areas.Do you think this is okay???
Thanks..
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DarrenWiens2
MVP Honored Contributor
Better would be to Union your pads and buffered roads, then Erase that from the total. If you simply subtract the separate areas of pads and buffered roads from the total, you'll count any areas of overlap between the two twice.
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ABDALLAMOHAMED
Occasional Contributor
Thanks a lot for your response..Double counting is the problem I was thinking of..Okay let me try with the union tool and see how it goes..I will let you know about the result...Best..
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