AutoCAD BPOLY results in negative area in ArcGIS

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11-14-2017 06:24 AM
DanJames
New Contributor II

Using the ArcGIS for AutoCAD tool:

ArcGIS is interpreting a negative area (wrong ring ordering) when I synchronize a shape I have made from AutoCAD using BPOLY. I make a hard angled polygon in AutoCAD (meaning no smooth arcs). Then, I create a circle at one of the corners. After expanding the circle, I use the BPOLY command in AutoCAD to get a new shape. The new shape created then is synchronized to my enterprise GDB and has a negative area. I have tried using the REVERSE command, exploding and rejoining, and a various few different things in AutoCAD to fix the drawing order to try and correct the issue. However, the only consistent solution I have found is for me to go into ArcGIS and export the feature(s) from the enterprise GDB, repair geometry, and replace the feature(s) altogether. Since the BPOLY command will continue to be used in this manner, is there a way I can fix this from AutoCAD? 

Thank you in advance.

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3 Replies
DanJames
New Contributor II

For anyone that may ever read this, I have figured out the answer to my own problem. It is not the BPOLY tool that causes negative area in ArcGIS - it is the way that CAD draws a circle and arc. CAD assumes a clockwise rotation in the drawing and therefore causes the shape to be negative in ArcGIS. When you combine this shape with a normal polygon, ArcGIS does not know how to reorder the rings in that it has part of the rings are formed from a circle or arc. If the arc is drawn counter clockwise, then the shape it is joined with will become positive. The shape will be negative when the arc is drawn clockwise. CAD always draws the circle clockwise. The solution is to finish the BPOLY feature, then type "reverse" in the command line in order to reverse the drawing from clockwise to counter clockwise. Then the shape will end up with a positive area when it reaches ArcGIS.

XanderBakker
Esri Esteemed Contributor

In ArcGIS you can run Repair Geometry—Help | ArcGIS Desktop to solve these type of problems.

DanJames
New Contributor II

Thank you for the feedback and this is true; exactly what we were having to do. But I want the CAD users to be submitting geometry that has a positive value back into the feature service, not have to export the entire feature database, repair geometry, then push the fixes back in. This is not time economical. I don't know why ArcGIS cannot understand the ring order coming from a BPOLY shape created using a circle, but it doesn't understand the drawing order. I believe I have solved this issue above though, until it doesn't prove to work. 

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