acdbregion getArea =0,but the area of region is not 0 in fact

[475867377]

the region is unioned by two regions .but the area get by api getArea() is 0.in cad property window can not show area and perimeter. i use command "area" to caculate area but failed. is there anything wrong?

[tbrammer]

Can you please post the DWG with the region in question?

You wrote that the region is a union of two regions. Do both have a valid area? Can you post a DWG with those regions as well? 

Do you know how the regions were created?

Which AutoCAD version are you using?

[475867377]

the region is created by api booleanOper(AcDb::kBoolUnite).it have merged the other region.the version of CAD is 2018.

[tbrammer]

Again: Can you please post the DWG with the region in question and if possible a DWG with the two regions that you merged? 

Have you tried to open the DWG with _RECOVER?

Can you check the DWG with a newer version of AutoCAD?

[475867377]

this is the dwg.

[tbrammer · Accepted solution]

I can reproduce the behaviour with AutoCAD 2024. 

The two regions in the DWG are valid. But if I _UNITE them, the resulting region looks OK, but it doesn't show geometry properties like area and circumference.

If I use the command SNOOPENTS from ArxDbg.arx (<ARX>\samples\database\ARXDBG) I get the error messages

ERROR calling AcDbRegion::getAreaProp()
ARX ERROR: eInvalidInput

Also the AutoCAD command _AREA _OBJECT can't calculate the area.

The AutoCAD command _MASSPROP however displays values for area (Fläche) and circumference (Umfang):

The geometry of one region is very complex. It has a lot of "touching points" that makes it hard to decide whether there is one region with a hole or multiple separate regions. I suppose that this causes the problem.

Looks like a bug. So I think this is a case for the AutoCAD product support.

I managed to create a valid united region like this:

1. _EXPLODE all regions to lines
2. Create new regions with _REGION and select all lines. 
3. Unite all new regions with _UNITE

See attached DWG. I think you can do the same programmatically with ObjectARX. This could be a workaround for you.

[475867377]

i have resolved the problem.the region is create  by the AcDb3dPolyline which vertexs ' z value is 0.i change to AcDbPolyline and setElevation(0),then the problem is resolved.thank you for your help.

[475867377]

i have resolved the problem.the region is create  by the AcDb3dPolyline which vertexs ' z value is 0.i change to AcDbPolyline and setElevation(0),then the problem is resolved.thank you for your help.