Migratory distance from Africa?

Question

I have a raster data where pixel value of each cell represents the potential minimum travel time across the cell in old world.

Now, I need to find the minimum travel time of some points from Addis Ababa (Ethiopia) in Arcmap. This needs to be the travel time on land (no seas or oceans). The raster data is missing values on seas and oceans.

In other words, I need the sum of pixel values on the route between a point and Addis Ababa, but only going on land.

Any suggestions on how to do this? Do you know any alternative methods to calculate migratory distance from Africa?

Answer 1

The calculation you are doing is least cost path. This is a standard approach to the sort of analysis you are doing. For an overview, have a look at the ArcGIS help to explain the process here:

1. Least cost path
2. Understanding cost-distance calculation
3. Cost-Distance Tool

Use NoData (the sea) to denote areas that cannot be crossed.

(If you are using QGIS, have a look at this thread)