[GRASS-dev] Re: [GRASS GIS] #1088: r.fillnulls: support other interpolation methods

[Michael Barton]

Thanks Markus,

This is very close to the methods we used in the last month to rebuild early Holocene landscapes in eastern Spain. Your tips are very useful. I only wish we'd had them before we did a lot of experimentation.

Cheers
Michael
______________________________
C. Michael Barton 
Director, Center for Social Dynamics & Complexity
Professor of Anthropology, School of Human Evolution & Social Change
Arizona State University
Tempe, AZ  85287-2402
USA

voice: 	480-965-6262 (SHESC), 480-727-9746 (CSDC)
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www: 	http://csdc.asu.edu, http://shesc.asu.edu
		http://www.public.asu.edu/~cmbarton

On Jun 21, 2010, at 9:00 AM, grass-dev-request at lists.osgeo.org wrote:

> Message: 2
> Date: Mon, 21 Jun 2010 08:29:31 -0000
> From: "GRASS GIS" <trac at osgeo.org>
> Subject: [GRASS-dev] Re: [GRASS GIS] #1088: r.fillnulls: support other
> 	interpolation methods
> To: undisclosed-recipients:;
> Message-ID: <052.ec39642cf05ae49be4ce809f1417fb9d at osgeo.org>
> Content-Type: text/plain; charset="utf-8"
> 
> #1088: r.fillnulls: support other interpolation methods
> -------------------------+--------------------------------------------------
> Reporter:  kyngchaos    |       Owner:  grass-dev@???              
>     Type:  enhancement  |      Status:  new                      
> Priority:  normal       |   Milestone:  6.5.0                    
> Component:  Raster       |     Version:  svn-develbranch6         
> Keywords:  fillnulls    |    Platform:  All                      
>      Cpu:  All          |  
> -------------------------+--------------------------------------------------
> 
> Comment(by mmetz):
> 
> In grass 7, it's already implemented in r.resamp.bspline. r.resamp.bspline
> interpolates a raster to the current resolution, filling NULL cells on the
> fly, or optionally only interpolates NULL
> cells. Available methods are bilinear and bicubic, tested with SRTM data,
> filling large gaps in the European Alps.
> 
> For grass 6.x, I would use a different approach to r.fillnulls to follow
> the design of v.surf.bspline, because only interpolating NULL cells is
> already possible with v.surf.bspline:
> 
> Create a new raster where NULL cells in the original surface raster are
> set to something else than NULL, others to NULL. Convert both raster maps
> to vector points. Use the vector points representing NULL cells as sparse
> points input for v.surf.bspline. Recommended settings for v.surf.bspline
> in this case are sie = 2 * ewres, sin = 2 * nsres, lambda = 0.005 (best in
> my tests, should be somewhere between 0.001 and 0.01). The output raster
> holds the interpolated NULL cells and can be patched with the original
> surface.
> 
> Although all lidar tools work within the current region, none respects a
> MASK. I'm not sure how this could be implemented properly and efficiently,
> currently there will be IMHO harmless warnings about no points in the
> current subregion.
> 
> Markus M
> 
> -- 
> Ticket URL: <https://trac.osgeo.org/grass/ticket/1088#comment:7>
> GRASS GIS <http://grass.osgeo.org>
>