[GIS] Questions on smooth lines on soil polygon

Question

In a couple of weeks I am going to do QA/QC on soil polygons and I'm wonder if there is a way for me to run a script or a tool box that allow me to find the jagged lines ?

Alternative, my plan would be to set up using a quad layer for each quad and then review the lines that need to be smooth. I would create a new layer to mark an error that need to be correct smooth line. I feel that it would take about a week or so to complete the work. The layer itself is a big file.

In the past, I have had convert from polygon to polyline but it took a lot of time and work to clean up. If you do that, there would be probably a lot of gaps in between lines ane would create gaps and produce topology errors.

Does anyone have a suggest a better way around it ? I am using ArcGIS 9.3.1 SP3.

Thanks !

Answer 1

Could you use Simplify Polygon (from the Cartography toolbox) and select the Bend_simplify option rather than the Point Remove, which will help you maintain the shape of the polygons. Use the 'Maximum Allowable Offset' to set your tolerance. The 'Maximum Area' setting will allow you to kill tiny polygons if they fall below the practical (soil sampling) resolution of your data. Set 'Handling Topological Errors' to 'Resolve Errors'.

In you old method I presume you smooth the lines and reconvert to polygons again. I've done a very similar thing too for many reasons. This can give you overlapping polygons with gaps. You can save time with your topological errors in two ways.

1. The first is to use Coverages (remember those?). They have strict topology conformance unlike the ArcGIS geodatabase (at least the one in use in v9.3). Convert your data to a coverage (you need the ArcInfo Licence for this though) and smooth your polygons, kill slivers, build/clean (just like in the good ol' days) then convert back to geodatabase or shapefile. ESRI were mad to deprecate the Coverage IMHO...
2. If you don't have ArcInfo (so can't use the sublime Coverage format) and must follow your procedure of converting to polylines, do what you normally do until you reconvert back to polygons. Next Integrate the polygon layer with itself. This will handle most of the issues but there may be a few gaps left (overlaps should be gone now). Next union or intersect your polygons with a single polygon equal to the entire area. This fills the gaps and then you can use Eliminate if you have it, to get rid of these 'gap polygons' (or some combination of Dissolve and Spatial Join to re-attribute afterwards if your licence dosent give you Eliminate). It sounds like a lot of work, but if you have a lot of data, a few automated steps are far better than doing it all by hand.

Integrating a file with itself is a little trick I've found handy on many occasions as a Topology clean-up hack. I just tested the Simplify routine in ArcGIS 10 and it did not return any overlaps but, from memory, I expected some when I used v9.3. So maybe ESRI have improved their code in V10. If you do get bad topology in V9.3 using simplify, then do the Integrate trick.