[GRASS-dev] Re: grass-dev Digest, Vol 33, Issue 37

[Michael Barton]

On Jan 15, 2009, at 5:22 AM, <grass-dev-request at lists.osgeo.org> wrote:

> Date: Thu, 15 Jan 2009 09:39:00 -0000
> From: "GRASS GIS" <trac at osgeo.org>
> Subject: [GRASS-dev] Re: [GRASS GIS] #398: r.watershed with MFD
> To: undisclosed-recipients:;
> Message-ID: <048.b6a7364e017fd287d20f06fe708aedbe at osgeo.org>
> Content-Type: text/plain; charset="utf-8"
>
> #398: r.watershed with MFD
> -------------------------- 
> +-------------------------------------------------
>  Reporter:  mmetz        |       Owner:  grass-dev at lists.osgeo.org
>      Type:  enhancement  |      Status:  reopened
>  Priority:  minor        |   Milestone:  7.0.0
> Component:  Raster       |     Version:  svn-trunk
> Resolution:               |    Keywords:
>  Platform:  Unspecified  |         Cpu:  Unspecified
> -------------------------- 
> +-------------------------------------------------
> Comment (by mmetz):
>
> I have submitted a new version of r.watershed to trunk with various
> changes
>
> MFD is fully supported: drainage directions, stream segments, basins,
> half-basins, RUSLE LS and S factors are all in accordance with MFD  
> flow
> accumulation.
>
> The module is slightly faster and uses a bit less memory. See updated
> documentation to estimate memory requirements for the ram (all in  
> memory)
> mode (max 31 MB of RAM for 1 million cells).
>
> It is no longer necessary to create a MASK for cells with unknown
> elevation (NULL values). All cells with unknown elevation (masked or  
> NULL
> values) are skipped. Zero and negative values are valid elevation  
> values.
>
> The color rules generated by the module for flow accumulation have  
> worked
> for all tests so far and allow visual inspection without manually
> assigning a color table. I'm using standard deviation and log  
> transform,
> based on Hamish's (I think) suggestions. Visual output is obsolete but
> left for comparison.
>
> The output drainage direction is slightly changed in case an input map
> with real depressions was supplied. Previously, real depressions had a
> drainage direction of -1, but -1 was and is a valid drainage direction
> indicating a drainage of 45 degree CCW from East towards a cell with
> unknown elevation. Therefore real depressions have now a drainage
> direction of 0. As before, if a cell drains due East the drainage
> direction is 360 degrees, 0 (zero) as drainage direction was unused.
>
> RUSLE LS and S factor output maps are now of type DCELL without
> multiplication by 100. Both factors have always been processed as type
> double, previously the output maps for the two factors were written  
> out by
> typecasting from (DCELL * 100) to CELL.
>
> Please read the updated documentation before using the new module.
>
> Best regards,

Markus,

Can this go into develbranch_6 too?

Michael