topic Re: No Service Area Polygons Generated for Larger Areas in ArcGIS Network Analyst Questions

No Service Area Polygons Generated for Larger Areas

JeffreyKlagholz — Tue, 03 Apr 2012 17:25:13 GMT

I am creating state-by-state service area analyses for 15, 30, and 60 min drive times to facilities. I've had no problems solving the smaller states, but when I try to do CA, TX, etc., no polygons are generated after running Solve (even though I'll get the green check saying it ran successfully). No error messages either.

I've already gone into regedit and edited the DWORD values in case it was a memory issue, but no change in the outcome.

Any ideas would be greatly appreciated.

Re: No Service Area Polygons Generated for Larger Areas

JaySandhu — Tue, 03 Apr 2012 18:02:18 GMT

First, what version of the software are you using and how much RAM do you have on the machine. Second, are you solving a 60 minute drive time from one location or multiple locations? Generally speaking, larger service areas may not work due to memory limitations but 60 minutes is not that large and should succeed. Also, what settings do you have on the polygon generation: generalized/trim/merge/etc.

Also what DWORD did you change/edit using regedit?

Jay Sandhu

Re: No Service Area Polygons Generated for Larger Areas

JeffreyKlagholz — Tue, 03 Apr 2012 18:42:26 GMT

Using 10.0 and my computer has 4.0 GB RAM. I'm using the 15, 30, and 60 minute intervals for a TRAVEL_TO analysis. There are ~150 facilities (using CA hospitals).

For polygon generation I'm using Simple_Polys; Merge; Disks; and Trim Polygons.

Here are the settings/values I put in using regedit:
Service Area
EdgeChunk- 100000
ForceChunking- 1
PolygonChunkSize- 5

Re: No Service Area Polygons Generated for Larger Areas

JaySandhu — Tue, 03 Apr 2012 20:46:48 GMT

Since you are doing a simultaneous 60 minute service area from 150 locations with the Merge option, that means it has to generate all the 150 service areas to merge them together. In that case the registry entries to chunk them in polygons of 5 will not work. You could choose the overlapping option and then merge the polygons later if needed (e.g., using Dissolve tool).

Jay Sandhu

Re: No Service Area Polygons Generated for Larger Areas

JeffreyKlagholz — Wed, 04 Apr 2012 13:46:29 GMT

Tried running with the overlap option and got the same result. After about 80 minutes of runtime, the status bar jumped from "solve 22% Complete" to being done, with no polygons generated.

Is this still a memory issue, or is the program just timing out some reason midway through the process?

Re: No Service Area Polygons Generated for Larger Areas

RobertGarrity — Wed, 04 Apr 2012 17:05:06 GMT

Hello, I just want to jump in here and make sure that there wasn't a misunderstanding. It read like chunking might have been turned off in the last analysis--it should be on. Jeffrey, did you set the registry key for chunking then solve the analysis using overlapping (instead of merge)? The point Jay was making was that chunking doesn't work with merging polygons. The merge operation is a post process which requires all the polygons to be stored in memory during the solve so that the 150 or so polygons can be merged in the end. The Overlapping option creates polygons that are completely independent of one another and allows the memory to be cleared after each "chunk".

Robert

Re: No Service Area Polygons Generated for Larger Areas

JeffreyKlagholz — Wed, 04 Apr 2012 18:45:30 GMT

Robert,

Thanks for the input. While I actually didn't know the details you just explained, I did still have chunking turned on when I ran the analysis with the Overlap option.

Re: No Service Area Polygons Generated for Larger Areas

JaySandhu — Thu, 05 Apr 2012 20:22:35 GMT

Make sure you followed the instructions here when setting up the registry keys for ArcGIS 10.0
http://support.esri.com/en/knowledgebase/techarticles/detail/38426

If the keys are in the right plance and they have not worked, then set the PolygonChunkSize to 1 and re-run. This will tell it to solve each facility and write out results befoe moving on the the next one.

Jay Sandhu

Re: No Service Area Polygons Generated for Larger Areas

JeffreyKlagholz — Thu, 12 Apr 2012 12:15:55 GMT

Thanks, Jay. The larger states work now I've set the value at 1. However, I'm still having the same problem when trying to run at a national level, for which there are over 2,500 facilities. Is the program simply not meant to handle a request that large?