topic Re: why is my polygon collapsing and disapearing in ArcGIS Pro Questions

why is my polygon collapsing and disapearing

Myh13 — Mon, 06 Mar 2023 09:12:20 GMT

Hello

I have feature class (polygon) not created by me. when i try to draw a polygon if the vertices are very close to each other the collapse when i finish the drawing.

the is gif showing the problem.

Re: why is my polygon collapsing and disapearing

Myh13 — Mon, 06 Mar 2023 13:56:43 GMT

I tried to add a new feature class. And it is working perfectly

Re: why is my polygon collapsing and disapearing

George_Thompson — Mon, 06 Mar 2023 14:10:47 GMT

Maybe something with the tolerances for that feature class is causing an issue?

Re: why is my polygon collapsing and disapearing

Myh13 — Mon, 06 Mar 2023 14:29:19 GMT

here is another example of what is happening

https://im4.ezgif.com/tmp/ezgif-4-a9aba3af7d.gif

Re: why is my polygon collapsing and disapearing

Myh13 — Mon, 06 Mar 2023 15:00:11 GMT

maybe you are rught. I check the xy tolerance and it says 0.001 deg. is it too high ? and how do you change it ?

Re: why is my polygon collapsing and disapearing

Myh13 — Mon, 06 Mar 2023 15:01:41 GMT

the distance between the collapsed two point is more than 100m.

Re: why is my polygon collapsing and disapearing

Margaret_M_Maher — Mon, 06 Mar 2023 15:41:21 GMT

I presume the data is stored in a geodatabase feature dataset, and I see that you are editing data in a Geographic Coordinate System with units in decimal degrees. There are 2 things going on here. 1] a degee is an angle. On the ground, at the Equator, OR in the north-south direction, a degee on the ground is 69.2 miles, or 111 kilometers. If you are creating very small polygons with units of degrees, the actual linear distance between the vertices on the ground will not be large enough for the software to see that the vertices are NOT coincident. The vertices will be snapped together automatically, and the polygon will collapse. 2] The geodatabase has XY Tolerance and XY Resolution for the features in the feature class or feature dataset. If the vertices are closer together than the XY Resolution the software will assume they are coincident and again will snap the vertices together and collapse the polgyon.

Please refer to the Knowledge article at the link below. This article sorts out the process of deciding which of the many projections and coordinate systems available is best for your projection - it depends on what you want to measure! https://support.esri.com/en/technical-article/000006113