repair geometry - self intersections

[danbecker]

Several thousand polygon feat. classes contain geometry problems, almost all self intersections.

I need to repair the self intersections for a variety of reasons:
1. negative area calculations
2. I need to remove all arc segments from all features; to do so with only an ArcView license, I have to run shape_density.cal, (/www.ian-ko.com) on shape field. With geom. issues this does not run correctly.
3. Oracle database that features are being loaded into checks for geom. issues

After a self intersection(s) is identified, the repair geom. tool is ran. However, the resulting features differs significantly from the original feature. I understand the self intersections polys are dissolved...any way to correct this? i.e. repair geometry but not significantly alter the feature?

I attached an image of the original feature and after the geom. had been repaired.

thanks

[danbecker]

more info....

If I create a new feat. dataset, then import the feat. class that contains self intersections, and re-run check geometry; no errors are reported!

Could someone explain?

[ChrisSnyder]

Note sure why, but:

1. If I copy data out of our coprorate SDE database to a FGDB and retain the original 1ft XY tolerance I have tons f self-intersection errors.

2. If I copy data out of our coprorate SDE database to a FGDB but specify finer tolerance and/or resolution (example: 0.001 Meters) I have no self-intersection errors.

Starting years ago, I use option #2.

gp.XYTolerance = "0.001 METERS"
gp.XYResolution = "0.0005 METERS"

[danbecker]

thanks!

confirmed. If I create a new feat. dataset with smaller tolerance, (0.0000000089 degrees) then import the feat. classes, no self intersections are found.

Too bad you can't set tolerances; going to have to recreate thousands of feat. datasets; then import the feat. classes.

[ChrisSnyder]

Too bad you can't set tolerances

Do you mean after the fact? Just re-copy the copies with the CopyFeatures tool (or whatever tool) and set the tolerance and resolution settings to the ones I specified in the environment settings (general section). These are the ESRI defaults by the way - the ones you get if you create a brand new FC from scratch. The "METER" units get automatically translated to whatever map units your FCs are defined as.

[JensWeißer]

is there any loss of data using the REPAIR GEOMETRY Tool?

The output of my thesis is an area and I used this tool sometimes, that's why it would be good to know,

if the created area is smaller than the area which could be created without using this tool?

[DanPatterson_Retired]

a quick answer .... redo the calculation for area etc in a new field in the table ... best test

[PaulLohr]

This has been a helpful thread. The Integrate geoprocessing tool took care of self intersections which could not be removed by the Repair Geometry tool. In my case it was set very low - at 0.01 feet. I would think setting this properly depends on how tight or loose the self intersections are. This was with version 10.2.2 and a file geodatabase polygon feature class.