topic Re: The least cost distances between more than two points in ArcGIS Spatial Analyst Questions

The least cost distances between more than two points

XiaochenLi — Wed, 02 Oct 2013 08:43:30 GMT

Hi, colleagues,
I am learning the ArcGIS spatial analyst. I have some problems. My questions are listed as below.
1. What is the difference between the layer file with ???end to end blue arrows??? icon and the the layer file with the yellow diamond icon?
2. What is the format of the layer files with ???end to end blue arrows??? icon?
3. Is the format of the layer files with a yellow diamond icon .lyr?
4. Should I select the layer file (e.g. elevation) with ???end to end blue arrows??? icon or layer file with yellow diamond icon?
5. I would like to calculate the least cost distances (LCD) between more than two points, however the ???Spatial Analyst Tutorial??? provides the workflow for only two points (the final site and destination in Stowe.gdb). Can you tell me the complete workflow for calculating the LCDs among more than two points (see, among the five schools in the tutorial)?
Attached please find the model I made.
Thanks

Re: The least cost distances between more than two points

XanderBakker — Wed, 02 Oct 2013 10:24:12 GMT

Hi,

1. What is the difference between the layer file with �??end to end blue arrows�?? icon and the the layer file with the yellow diamond icon?
2. What is the format of the layer files with �??end to end blue arrows�?? icon?
3. Is the format of the layer files with a yellow diamond icon .lyr?
4. Should I select the layer file (e.g. elevation) with �??end to end blue arrows�?? icon or layer file with yellow diamond icon?

Data variables are shown with the Model Variable icon (what you refer to as 'end to end blue arrows'), and layers from the ArcMap table of contents are shown with the Layer icon ('yellow diamond icon'). In your case they both refer to the same data source, but in order to avoid adding the same layer twice as a different variable, you should use the Model Variable icon ('end to end blue arrows').

You can read more about this in the topic Adding and connecting data and tools (lower part)

5. I would like to calculate the least cost distances (LCD) between more than two points, however the �??Spatial Analyst Tutorial�?? provides the workflow for only two points (the final site and destination in Stowe.gdb). Can you tell me the complete workflow for calculating the LCDs among more than two points (see, among the five schools in the tutorial)?

If there are multiple cells or zones as input destinations, the least-cost path can be calculated from each cell (resulting in multiple paths, one path for each cell), each zone (one path from each zone), or by layer (only one path, the cheapest from any zone). A parameter in the tool specifies which process should be utilized.
Source: http://resources.arcgis.com/en/help/main/10.2/index.html#//009z00000021000000

Your Cost Path is colored white since it cannot be executed. It requires at least three parameters and only two are specified. In your case the "in_destination_data" is missing. See Help topic:
http://resources.arcgis.com/en/help/main/10.2/index.html#//009z00000019000000

So in short:
The Cost Distance will create a accessibility from 1 or more sources
The Cost Path will calculate the path from 1 or more destinations back to the best accessible source

Kind regards,

Xander

Re: The least cost distances between more than two points

XiaochenLi — Thu, 03 Oct 2013 03:49:07 GMT

Dear Xander,

Thank you very much for your reply. Your instructions are very useful and helpful to me. I'll practice according to your instructions. Thanks again.

Best regards,

Xiaochen

---------------------------------

Hi,

Data variables are shown with the Model Variable icon (what you refer to as 'end to end blue arrows'), and layers from the ArcMap table of contents are shown with the Layer icon ('yellow diamond icon'). In your case they both refer to the same data source, but in order to avoid adding the same layer twice as a different variable, you should use the Model Variable icon ('end to end blue arrows').

You can read more about this in the topic Adding and connecting data and tools (lower part)

If there are multiple cells or zones as input destinations, the least-cost path can be calculated from each cell (resulting in multiple paths, one path for each cell), each zone (one path from each zone), or by layer (only one path, the cheapest from any zone). A parameter in the tool specifies which process should be utilized.
Source: http://resources.arcgis.com/en/help/main/10.2/index.html#//009z00000021000000

Your Cost Path is colored white since it cannot be executed. It requires at least three parameters and only two are specified. In your case the "in_destination_data" is missing. See Help topic:
http://resources.arcgis.com/en/help/main/10.2/index.html#//009z00000019000000

So in short:
The Cost Distance will create a accessibility from 1 or more sources
The Cost Path will calculate the path from 1 or more destinations back to the best accessible source

Kind regards,

Xander

Re: The least cost distances between more than two points

StephanieGarvis — Thu, 03 Oct 2013 17:57:08 GMT

Hi Xander, along these same lines, do you know how to run a least cost path between multiple points that results in a pairwise least cost path for all points?

So, if you have 5 points, you would have 10 paths?

Thanks,
Stephanie Garvis

Re: The least cost distances between more than two points

XanderBakker — Fri, 04 Oct 2013 05:46:22 GMT

Hi Xander, along these same lines, do you know how to run a least cost path between multiple points that results in a pairwise least cost path for all points?

So, if you have 5 points, you would have 10 paths?

Thanks,
Stephanie Garvis

Hi Stephanie,

If you would like to calculate from a set of 5 points the least cost path between each pair of points, you shoud create cost distance rasters for each point. So we're talking about 1 calculation for each point (5 in total). Then for point 1 you take the cost distance raster and the 4 other points to calculate the 4 paths. For point number 2 you take points 3, 4 and 5 and calculate the paths. For point number 3 take points 4 and 5 en for point 4 take point 5. I do not see a faster way since to determine the path to a source you will need the cost distance raster specifically for that source.

Kind regards,

Xander

Re: The least cost distances between more than two points

StephanieGarvis — Fri, 04 Oct 2013 14:04:55 GMT

Hi Stephanie,

If you would like to calculate from a set of 5 points the least cost path between each pair of points, you shoud create cost distance rasters for each point. So we're talking about 1 calculation for each point (5 in total). Then for point 1 you take the cost distance raster and the 4 other points to calculate the 4 paths. For point number 2 you take points 3, 4 and 5 and calculate the paths. For point number 3 take points 4 and 5 en for point 4 take point 5. I do not see a faster way since to determine the path to a source you will need the cost distance raster specifically for that source.

Kind regards,

Xander

Hi again, thanks for the response.

- Stephanie