topic Re: Shorted distance from many grid points to a beach and coastal shelf in Mapping Questions

Shortest distance from many grid points to a beach and coastal shelf

LeonBerard — Tue, 15 Mar 2016 01:12:47 GMT

Hi all,

I am trying to calculate the shortest distance from a large number of points (created using 'genvecgrid' in Geospatial Modelling Environment) to both a single point (representing the breeding beach) and a line (representing the coastal shelf drop-off). The overall goal here is to find for every point the distance from the beach and coastal shelf to each grid point which will let me analyse at-sea resource selection of the penguins being studied.

The problematic part is that the distances need to travel around the coast, so they are representative of the shortest distance a penguin could travel by sea between the points. The breeding site (beach) is on the outside of a peninsula, and the coastline is very uneven.

What would be the best way to calculate the distances for all these grid points?

Many thanks.

Re: Shorted distance from many grid points to a beach and coastal shelf

LeonBerard — Tue, 15 Mar 2016 02:06:29 GMT

Update: Have just installed trial copies of Network and Spatial analyst.

Re: Shorted distance from many grid points to a beach and coastal shelf

DanPatterson_Retired — Tue, 15 Mar 2016 02:17:35 GMT

You have ruled out the two suggestions, particularly the costpath analysis for the spatial analyst extension. Simply setting your cost surface to make land a high cost and water a low one, the path would follow the shore, you could even add other impedance issues, perhaps based upon proximity to shore etc etc. Perhaps, you might consider a trial of extension (which anyone can do) once you have formulated a game plan after reading.

Re: Shorted distance from many grid points to a beach and coastal shelf

LeonBerard — Tue, 15 Mar 2016 03:58:36 GMT

Hi Dan,

Thanks for the response. I have since activated a trial version of the spatial analyst extension and am working through the instructions here https://groups.google.com/forum/#!topic/gis-in-ecology-forum/iotTbwv27yE as they appear to address my question. I am having little success at getting meaningful outputs (a table with distances from all points to the nesting site) but will keep at it and hopefully make some headway.

Re: Shorted distance from many grid points to a beach and coastal shelf

DanPatterson_Retired — Tue, 15 Mar 2016 04:42:19 GMT

the link doesn't work on Safari you have an http and https in the same line

for the cost distance cost path analysis, make sure you see some of these

Understanding cost distance analysis—Help | ArcGIS for Desktop

plus the sublinks on the left of the window