Problem with cost distance

Discussion created by cathy_baobao on Oct 5, 2011
Latest reply on Oct 7, 2011 by dgalbraith
Hi, I am trying to calculate a distance surface where for each cell, it will return the shortest transportation to ports, including shortest Euclidean distance to the roads, and then the shortest distance to a port along the road network.

There are a range of ports so the I am trying to use the cost distance tool to calculate the network distance from each road cell to the cloest port, by using a cost surface containing only road cells with the value of 1 (equal weight).

The output is also cells along the road only, however, I found the output cells are not 100% overlaying the input road cells. It looks like it is resampled. The problem is that, it is only using one port location as the source. I would expect the tool to choose the closest port for different cells.

I noticed that because of the resampling problem, some of the ports are not within the output raster cells any more. Is it a reason for the cost distance tool not identifying these ports as source locations? But for those ports that are still within the output cells, they are not used as the source as they should, either. So does anyone know what is the issue here?