[R-sig-Geo] Correspondence between gstat and ArcGIS functionality?

[Wesley Roberts]

Hi Jeff,

You may not need to use gstat or indeed R. NASA have kindly developed
the following software to take care of the gaps. Be aware though that
the method requires several images from different dates of the same
area. 

http://landsathandbook.gsfc.nasa.gov/handbook/software/gap_filling_software.html

Alternatively GRASS GIS has a function / module called r.fillnulls
which uses splines interpolation to fill the gaps.

http://grass.itc.it/grass65/manuals/html65_user/r.fillnulls.html 

Hope this helps,

Wesley

Wesley Roberts MSc.
Researcher: Earth Observation
Natural Resources & the Environment (NRE)
CSIR
Tel: +27 (0)21 888-2490
Fax: +27 (0)21 888-2693
"To know the road ahead, ask those coming back."
- Chinese proverb


>>> "Prof. Jeffrey Cardille" <jeffrey.cardille at umontreal.ca> 4/14/2010
9:47 PM >>>
Hello all,

This is my first posting to R-sig-geo; I looked for the answer in the
archives, but have not had any luck for my particular question. 

I have a newbie question about the correspondence between gstat and
ArcGIS.  I have a problem that gives very very satisfying results in
ArcGIS, and I would like to write a public function in R for others to
use that does the same thing.  The choice I used in Arc was "Universal"
and in the dropdown menu it says "Linear with Linear Drift".  My data
matrix is pretty standard:  2000 x 2000, with some NA, and values
between 0 and 255.

So I have a few questions.  Maybe I'll enumerate them.
1. Has anyone made a comprehensive list between ArcGIS functionality
and how to do it in gstat?

2. If not: does anyone know a simple correspondence between what ArcGIS
is doing and how to set up a gstat call for "Universal/Linear with
Linear Drift"?  I have looked online for precise details about Arc's
behavior, but haven't seen anything detailed enough.

3. Are there any tricks in gstat that make interpolation with gstat
especially fast or slow?  For example, if the numbers were treated
faster if they were between 0 and 1, or if NA should be recoded, or if I
should never use a data frame but always a matrix.  That sort of thing.

If not, I'll resort to trial and error and diving deeper into the gstat
documentation.  But it seems like a good idea to check in first.  For
anyone interested, I am trying to repair Landsat satellite photos, which
have big broken strips of nodata due to a mechanical failure.  The
strips are up to 14 pixels wide.  I need to do this 2000x2000
interpolation about 2000 times-- so speed differences of even a few
seconds or minutes are quite important..

Thanks!
Jeff

------------------------------------------
Prof. Jeffrey Cardille
jeffrey.cardille at umontreal.ca 

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