topic Re: centerlines from polygon canal network in Spatial Data Science Questions

centerlines from polygon canal network

GregoryLuna_Golya1 — Mon, 16 Feb 2015 00:02:58 GMT

Hello,

I was wondering if anybody has recently converted a complex polygon or raster canal network to centerlines? ESRI toolboxes or third party tools are moving targets so some of the old threads are hard to apply. The canal polygon network that I have was created by cutting out nearly 20,000 mounds and agricultural beds from a shallow lake system (archaeological example). The remaining canal polygon network is one large complex polygon. I converted it to a raster and tried the raster to polyline tool but ended up with a polyline feature class that filled in the canal cells with 800 million lines after running for a couple days. Obviously, not what I was looking. I didn't try the ArcScan vectorization since my raster was 1 or no data and ArcScan requires a 2 value raster. I can convert my raster and give that a try. Not sure if there is a method to convert my complex polygon directly to lines (centerlines). I'll attribute the resulting lines after the fact so I just need to create the skeleton or centerline features. Any ideas are welcome.

Thanks, Greg

Re: centerlines from polygon canal network

DarrenWiens2 — Mon, 16 Feb 2015 00:45:48 GMT

Have you looked into the Thin tool? It's not perfect, and takes some fiddling with parameters, but may get you where you want to go.

1.) Polygon to Raster

2.) Thin

3.) Raster to Polyline

Re: centerlines from polygon canal network

XanderBakker — Mon, 16 Feb 2015 00:52:15 GMT

A picture of what you are dealing with good do wonders...

From this thread: How to create a centerline from polygon in Arcgis 10 - Geographic Information Systems Stack Exchange

If you have the ArcInfo licence you can use Collapse Dual Lines To Centerline tool (Cartography) tool. This is in the Cartography Toolbox.
Alternatively, if you have Data Interoperability Suite, then you will have FME. There is also a tool in FME to get centerlines from polygons.
If you don't have access to an Advanced license or Data Interop, you may want to check out ET GeoWizards for ArcGIS. It has some features for finding center lines. createCenterlines

but you may give it a try in ArcScan too...

Re: centerlines from polygon canal network

GregoryLuna_Golya1 — Mon, 16 Feb 2015 01:19:07 GMT

Thanks, Here is a small area of the canal system. The white areas are raised agricultural fields or residential mounds. Trying to turn the canals into polylines for network analysis of movement through the canal system. There are some open pools and non-linear canal areas to add to the challenge. Greg

Re: centerlines from polygon canal network

DarrenWiens2 — Mon, 16 Feb 2015 01:21:56 GMT

The ET GeoWizards example Xander linked to seems to give good results, which should work for your canals:

Re: centerlines from polygon canal network

GregoryLuna_Golya1 — Mon, 16 Feb 2015 01:50:01 GMT

Thanks. Looks like I may have to make the investment. I don't see it among ET Geowizards free functions. I'm guessing that it will correctly create lines for my "cul-de-sacs". Greg

Re: centerlines from polygon canal network

XanderBakker — Mon, 16 Feb 2015 01:53:08 GMT

The network analysis you are planning, is a vector analysis? If not, you may be able to some "network" (accessibility) analysis in raster format...

Re: centerlines from polygon canal network

GregoryLuna_Golya1 — Mon, 16 Feb 2015 02:08:35 GMT

I was planning on vector analysis. I could manually rank the primary canals (some are very wide and could accommodate large transport canoes). Secondary and tertiary canals could also be attributed with the remainder assigned to the thin canals separating individual beds. The idea being that I can identify which fields/mounds were associated with larger village/wharves I have identified based on travel costs.

Re: centerlines from polygon canal network

GregoryLuna_Golya1 — Mon, 16 Feb 2015 02:20:12 GMT

Thanks. The open pools seem to be the biggest challenge. I'll play with the max width setting.

Re: centerlines from polygon canal network

GregoryLuna_Golya1 — Mon, 16 Feb 2015 22:19:18 GMT

Thanks for the feedback. I went with the ET GeoWizards' createCenterlines option. Pretty good results for my complex, messy dataset. Will require cleaning but was worth the investment. Greg

Re: centerlines from polygon canal network

FatihDur1 — Thu, 25 Jul 2019 06:15:20 GMT

Can you explain this a bit more please, the network accessibility in a raster?

Re: centerlines from polygon canal network

XanderBakker — Thu, 25 Jul 2019 13:13:30 GMT

Hi Fatih Dur ,

There are a couple of tools you can use to calculate the optimal route between multiple points in raster format (you will need to have access to the Spatial Analyst extension. This will require a raster that contains the "cost" for each cell. Normally this is creating by weighting several layers using tools like http://desktop.arcgis.com/en/arcmap/latest/tools/spatial-analyst-toolbox/weighted-overlay.htm. The resulting raster will be used in the cost distance tool to create a cost distance raster (cost for each cell calculated from one or multiple sources) and a back link raster that indicates for each cell the location of the neighboring cell with the lowest value. see: http://desktop.arcgis.com/en/arcmap/latest/tools/spatial-analyst-toolbox/cost-distance.htm. Using the cost distance and back link raster you run the last geoprocessing tool Cost Path that will create the route of the lowest cost from a destination location to the source. see http://desktop.arcgis.com/en/arcmap/latest/tools/spatial-analyst-toolbox/cost-path.htm