Simplify Raster to Polygon Output?

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11-19-2021 05:11 PM
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DanielQuinn
New Contributor

My problem is that the output to my Raster to Polygon is too complex and large in file size. How do I simplify it so it is more manageable to share, display, and work with as a feature class and as a shapefile?

Details:    ArcGIS Pro 2.8

  • I am conducting a slope analysis of a mountainous area approximately 10 square miles in size.
  • I ran the slope geoprocessing tool with a DEM (DTM with  a resolution of 1.44m) as the input.
  • Then I took the output raster and reclassed it to display the 7 different slope ranges I am interested in.
  • I then rand the raster to polygon tool because I need shapefiles as deliverables.

The output from the raster to polygon is so complex and the file size seems much larger than it needs to be. How do I simplify my feature class output so it is more manageable to share, display, and work with? 

Is it a matter of adjusting parameters on the tools in my process? Or is there a generalizing tool that is best suited?

Thanks for your consideration!

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4 Replies
DanPatterson
MVP Esteemed Contributor

It all depends on your raster, but you may want to generalize the raster before converting to vector

An overview of the Generalization toolset—ArcGIS Pro | Documentation

has lots of tools to generalize, for instance

Aggregate (Spatial Analyst)—ArcGIS Pro | Documentation

but do the generalization on the raster before reclassification.

Majority Filter (Spatial Analyst)—ArcGIS Pro | Documentation

can get rid of fiddly-bits that are small and will simplify this to

The options are there, the one, or process, that works best for your may take some experimentation.  These are but two examples


... sort of retired...
DuncanHornby
MVP Frequent Contributor

Another solution is don't write it to a shapefile. These are a very old format, persisting, in my opinion because they have been adopted by the open source community.

A file geodatabase is superior, faster and you can even compress the data into a smaller file size.

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Robert_LeClair
Esri Frequent Contributor

Another thing to try is go the Environment Settings for the Slope GP tool and set the Cell Size to a higher value like 5 m.  Rerun your workflow and save it out to file geodatabase raster dataset.  From there, run the Raster to Polygon GP tool and do not check "Simplify Features"  I think you'll get a better output.

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JimTenbrink
Esri Contributor

Hi Daniel

Have you tried the tool's 'simplify' option?

 

Simplify polygons
(Optional)

Determines if the output polygons will be smoothed into simpler shapes or conform to the input raster's cell edges.

  • Checked—The polygons will be smoothed into simpler shapes. The smoothing is done in such a way that the polygons contain a minimum number of segments while remaining as close as possible to the original raster cell edges. This is the default.
  • Unchecked—The edge of the polygons will conform exactly to the input raster's cell edges. With this option, converting the resulting polygon feature class back to a raster would produce a raster the same as the original.
Boolean

 

Also, the Create Multipart Features option will reduce the number of separate features by combining outer loops containing the same cell attribute into a single feature containing a multi-part polygon.

 

James TenBrink

spatial analyst team

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