[postgis-users] Re: flow direction (pointer) indexing

[Doug Nebert]

rajsingh at attbi.com wrote:
> The Massachusetts-Rhode Island USGS did something like
> this awhile ago. Information is here:
> http://ma.water.usgs.gov/streamstats/ and 
> http://water.usgs.gov/pubs/wri/wri004135/
> 
> I haven´t looked at the project in a few years, but my
> understanding is that, as Paul Ransey suggests, they
> went the raster route, implementing indexing schemes in 
> arcinfo GRID, then in arcview spatial analyst. 

Sue Jensen Greenlee pioneered this approach at the EROS
Data Center years ago and the algorithms have since been
implemented as commands in ARC GRID and IDRISI and other
raster packages. I am sure the algorithms are in the
literature, but this is most definitely a raster approach
and works quite well!

Doug.


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