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Area of overlapping closed polygons


jwkilgore

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I need to find the area of a closed polygon, less the area of a second partially overlapping polygon, and potentially less the area of other closed polygons.

 

Specifically, I have a squarish zone around a point that is counted as temporarily disturbed area during construction (closed polygon). An existing access road crosses through this area, but is NOT counted as temporarily disturbed area. I also have footings, permanent new stub roads and/or hammerheads (turn-around locations) that are counted as permanently disturbed, so these would also be subtracted from the temporary area.

 

I was originally going to use Hatch, but for some reason this isn't working well. Sometimes the hatch extends past lines for some reason, sometimes it says a valid boundary cannot be found, even where I click is completely surrounded by a closed polygon.

 

I'm trying to get a new guy to do this, and there are over 350 sites. The process has to be very simple. I attached one site as a zip file because I couldn't get it to less than 250k.

 

Any suggestions?

Sample.zip

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Not until just now (because I didn't know it existed), but it's giving me the same problem as Hatch. Actually, it looks like using pick points in Hatch calls the Boundary command internally, so I was already using Boundary.

 

Fortunately, the results did allow me to figure out what's blowing up the hatch; something hinky is happening with automatic boundary creation in the lower right corner. It's where the straight line segment transitions to an arc segment just before it hits a crossing line. If I zoom in closer to this point THEN do a hatch or boundary, it selects everything correctly. If I'm zoomed out far enough to see the entire polygon then the software tries to create a full circle around this tiny arc segment. Maybe something to do with how the arc is drawn on screen, but VIEWRES had no effect.

 

Has anyone tried this in a newer version of AutoCad? We're running 2007 because of client requirements.

 

I'll just get the new tech to do what he can and draw a big circle around the problem sites. I'll come back through and work on those myself. Assuming noone else has a better sollution.

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You might try looking for a custom lisp routine over at the Cadalyst Magazine website in their Tips and Tricks area.

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