topic Re: Spatial Analyst to assess multiple loops in ArcGIS Spatial Analyst Questions

Spatial Analyst to assess multiple loops

Juan_Poblete — Wed, 13 Aug 2014 09:50:10 GMT

Hi! I am kind of new to ArcGIS and I would appreciate some help. I need to create a network of footpaths joining multiple destinations and carry a cost / benefit analysis based on; landuse, slope and proximity to tourist attractions in order to identify suitable loops. The scenario is new footpaths within a natural state reserve) The sketch attached is a simplification of the real problem and does not take into account the real number of points (about 25) and the potential loops they can create (which I believe should rise up to 25!). In the sketch attached the result of the analysis should highlight which loop is preferable; 1-2-4-1 or 2-3-4-2. I have thought on carrying a cost distance analysis for each par of points and then carry a OD cost matrix. Is there a better way todo this?

Re: Spatial Analyst to assess multiple loops

DanPatterson_Retired — Wed, 13 Aug 2014 10:19:16 GMT

Your problem has not been clarified since your last post You will have to provide details as to how you are ascribing costs to the surface and to the paths themselves and where some sample origins and destinations are.

Re: Spatial Analyst to assess multiple loops

Juan_Poblete — Wed, 20 Aug 2014 10:26:31 GMT

Thank you for your answer Dan.

Initially I thought about ascribing cost based on the slope. I think a way to do this would be to create each path at one time using the cost distance tool. Setting one point to be the origin (number 1 for ex.) and the following (number 2) to be the destination.

From what I understand each cell composing the path would have a value. As a consequence of this each path would have an acummulative value too.

I would then have 4 individual paths and at least 3 loops with different accumulative values

1-2-4-1

2-3-4-2

3-4-1-3

What I want to identify using a OD matrix is which of the loops demands less effort in order to be completed. (In terms of a hikker, which path is easier).

Thank you

Re: Spatial Analyst to assess multiple loops

XanderBakker — Wed, 20 Aug 2014 13:25:22 GMT

From the image you include I think there are 4 different triangles that can be created, and you could change the start/end points for each triangle. There is a thing to keep in mind when doing a cost distance and a subsequent least cost path analysis including a weight based on the slope. In a slope map the cells hold the maximum slope of that cell in relation to its neighbors. You can however cross a cell in different ways (uphill, downhill or going straight). To compensate you could combine an aspect map with the slopes and assume that that a certain aspect is uphill and the opposite is downhill...

Below a link to a thread on hiking speeds, that might be interesting:

Hiking equation in python returns wrong results‌

Kind regards, Xander

Re: Spatial Analyst to assess multiple loops

Juan_Poblete — Fri, 22 Aug 2014 09:46:44 GMT

Thank you Xander.

I don't know what an aspect map is, but I will do a bit of research.

Regards

Juan

Re: Spatial Analyst to assess multiple loops

DanPatterson_Retired — Fri, 22 Aug 2014 09:51:31 GMT

slope aspect...the direction a slope faces