why is my polygon collapsing and disapearing

[Myh13]

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.

[Myh13]

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

[George_Thompson]

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

[Myh13]

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 ?

[Myh13]

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

[Myh13]

here is another example of what is happening

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

[Margaret_M_Maher · Accepted solution]

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