Shortest path tool/ Raindrop trace equivalent in Arc 10?

[ClaireByrne]

Hi all,

In Arc 9.x there was a shortest path tool in the Spatial Analyst toolbar which i had used previously to determine the path taken from a point to the sea. Essentially, this would give an indication as to where a pollutant would enter the river network, based on the DTM (and flow direction).

Does anyone know id there is there an equivalent to this tool hidden somewhere in Arc 10?

Many thanks,

Claire

[JohnPorter]

Eric,
     My recollection is that there was a big difference between the SA toolbar-based "shortest path" option and the "cost path" tool: what they produce. The old "shortest path" tool generated a set of graphical vectors that could be saved as a shapefile to produce good-looking graphics by manipulating line thickness etc.   Cost Path only generates a raster output, which is extremely hard to display in an attractive way. "Lines" are too thin (restricted to the input direction raster resolution) and because of the planar topology, the cost path tool can't generate distinguishable lines when paths to different destinations coincide. Thus if you want, as I'd like to, to subsequently select only paths with a length less than a certain value, it can't be done.

     I've been trying to find a workaround for the removed "shortest path" capability, but have had no luck yet. So it probably means I'll be installing Arc9 (again).  Sorry to bring up an old topic, but I'd really, really like to find a way to get vector, instead of raster, output for least-cost paths. I'd hoped this capability would be back in Arc10.1, but it appears to have fallen off the table.

Least-cost Paths are fundamentally lines and it would be great to have them returned that way!

  -John

Hi Tony,

The Shortest Path tool and the Cost Path GP tool are the same tool with different names. I don't have 9.x installed to take the screenshots necessary to highlight this so I'll just point you to some documentation.

Under Analysis Concepts > Distance Analysis > Least Cost Path and Least Cost Corridor you'll find  generic information regarding what cost path/corridor analysis is and how to perform it in ArcGIS.  On this page you will find instructions (Links) to Learn how to calculate least cost path using the Spatial Analyst toolbar and to Learn how to calculate least cost path using the Cost Path tool

In the Usage Tips section (for the GP tool documentation) it states the following:

"Cost Path can also be used to derive the path of least resistance down a digital elevation model (DEM). In this case, the DEM will be the input cost distance raster and the flow direction raster will be the input cost backlink raster. Valid flow direction raster values are 1, 2, 4, 8, 16, 32, 64, and 128; valid values in the backlink raster are 1, 2, 3, 4, 5, 6, 7, and 8. Both of these rasters are acceptable."

Attached are screenshots of a simple model I made and the results overlaid on a hillshade to give you some perspective.