|
|
| GeoCommunity Mailing List |
| |
| Mailing List Archives |
| Subject: | Re: [gislist] Filling gaps in grids (was: "grid cuting") |
| Date: |
04/11/2005 11:50:01 AM |
| From: |
Bing Du |
|
|
Dear Dr. Huber,
Thank you very much. I just used your method (also printed out your
webpage) and solved my problems. It's like magic.
This is the first time I posted my query here and I also thank the list
moderator to post my questions.
Thanks again.
Bing
-----Original Message-----
From: gislist-bounces@lists.thinkburst.com
[mailto:gislist-bounces@lists.thinkburst.com] On Behalf Of Quantitative
Decisions
Sent: Monday, April 11, 2005 10:48 AM
To: gislist@lists.thinkburst.com
Subject: Re: [gislist] Filling gaps in grids (was: "grid cuting")
At 09:27 AM 4/11/2005 -0500, Bing Du wrote:
>Dose any one know how to fill in nearby data into no data cells in a
>grid file of arcview3.2?
How this is done depends on the purpose. For grids that represent
continuous surfaces, you want to interpolate across the gaps. I
describe
the technique in general, using ArcView 3.2 (+Spatial Analyst) examples,
at
http://www.quantdec.com/SYSEN597/GTKAV/section9/chapter_29d.htm#Patching
. This method can be enhanced with regression techniques if you have
additional covariate datasets, but the mechanics of it will be quite
similar: you create a grid to interpolate across gaps and then either
fill
in only the NoData cells or some small neighborhood around each one with
the new values.
For grids that represent categorical variables, the process depends
strongly on how much and what kind of data you have and how you are
modeling them. There are ad-hoc methods, such as majority neighbor
fills,
there are statistical methods, such as logistic regression, there are
physical models of growth, proximity, size, and so on, and there are
probabilistic models, such as Markov models with spatial correlation,
that
can also be used. Most raster GISes, including AV 3.2's Spatial
Analyst,
support enough "map algebra" operations to carry out any of these
methods,
but few include the statistical exploration, diagnostic, and graphing
tools
needed to find the right coefficients to use or to estimate the possible
errors, so you would likely have to resort to a good statistical package
for that part of the work.
--Bill Huber
Quantitative Decisions
_______________________________________________
gislist mailing list
gislist@lists.geocomm.com
http://lists.geocomm.com/mailman/listinfo/gislist
_________________________________
This list is brought to you by
The GeoCommunity
http://www.geocomm.com/
_______________________________________________
gislist mailing list
gislist@lists.geocomm.com
http://lists.geocomm.com/mailman/listinfo/gislist
_________________________________
This list is brought to you by
The GeoCommunity
http://www.geocomm.com/
|
|
Sponsored by:
For information
regarding
advertising rates
Click Here!
|
