topic Calculate Locations: avoid creating identical locations in ArcGIS Network Analyst Questions

Calculate Locations: avoid creating identical locations

AndresSevtsuk — Sat, 30 Jul 2011 19:21:45 GMT

Hi all,

Using Calculate Locations, how could i avoid generating identical location values for points that all reach the same point on the network as closest? This commonly happens for point instances that are located around a tail-end of a cul-de-sac network segment.

I need them to be located at non-identical places on the network due to the way i use them as inputs in another algorithm that computes an adjacency matrix between all instances on the network. In that algorithm i use barrier costs at all points in an OD Cost Matrix to limit the search to only closest neighbors. However, if several points fall in the exact same location, then the OD Cost Matrix won't find them due to the overly high barrier cost. If I could have the Calculate Locations tool generate slightly different locations for all points, we could avoid this issues.

Thanks,

Andres
MIT Urban Studies & Planning

Re: Calculate Locations: avoid creating identical locations

DavidWilliams — Sun, 31 Jul 2011 09:06:18 GMT

Hi Andres,
You can do this with ETGeowizards using the disperse points tool, see:
http://www.ian-ko.com/ET_GeoWizards/UserGuide/dispersePoints.htm
Dave

Re: Calculate Locations: avoid creating identical locations

MichaelRice — Mon, 01 Aug 2011 14:21:14 GMT

Andres,

Unless you need barriers for some other purposes, you don't need to use barrier costs to limit the search to only the closest neighbors in the OD solver. You should be able to achieve this by setting a Target Destination Count (e.g., find the closest 5 for each origin) or by setting a cost Cutoff value on your search (e.g., only search up to 10 minutes away from each origin).

However, even if you must still use barriers, if you are using point barriers with additive cost, then it probably won't matter too much whether the barrier points are located right on top of each other versus located just next to each other on the same edge. This is because the cost to go through these barrier points will still add up to the same amount (assuming you do need to travel through each one). Are you asking to disperse the barrier points or your other origin (or destination) points?

Does this make sense? If you can further clarify your use case, perhaps we can come up with some better alternatives.