[GRASS-user] SRTM interpolation to sub-meter

GRASS GRASS user
1

Hi,

I have a SRTM DEM data from CGIAR (http://srtm.csi.cgiar.org/). I'm
trying to do local sea-level rise modelling.
Suppose I want it resampled to 30 meters with elevation at a
centimeters or millimeter units. Any thoughts on how to do this?

I believe the SRTM data are integer formats in meters. Converting
them to floating point does not necessaily enable you to do sub-meter
elevation calculations. Am I correct in my assumptions?

Thanks!

Maning
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2

On Fri, 23 Jun 2006 00:41:54 +0800
"maning sambale" <emmanuel.sambale@gmail.com> wrote:

Hi,

I have a SRTM DEM data from CGIAR (http://srtm.csi.cgiar.org/). I'm
trying to do local sea-level rise modelling.
Suppose I want it resampled to 30 meters with elevation at a
centimeters or millimeter units. Any thoughts on how to do this?

r.resamp.rst

or

r.to.vect, g.region res=30 -a, v.surf.rst/v.surf.idw

or

r.to.vect, g.region res=30 -a, v.to.rast, r.surf.nnbathy/r.surf.idw(2)

or

r.bilinear?

Try what's best for you :).

Maciek

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www.skarpatravel.pl

3

Remember that the vertical accuracy of SRTM data does not permit you
to make considerations within such small range of altitude values,....

Carlos

On 6/22/06, Maciek Sieczka <werchowyna@epf.pl> wrote:

On Fri, 23 Jun 2006 00:41:54 +0800
"maning sambale" <emmanuel.sambale@gmail.com> wrote:

> Hi,
>
> I have a SRTM DEM data from CGIAR (http://srtm.csi.cgiar.org/). I'm
> trying to do local sea-level rise modelling.
> Suppose I want it resampled to 30 meters with elevation at a
> centimeters or millimeter units. Any thoughts on how to do this?

r.resamp.rst

or

r.to.vect, g.region res=30 -a, v.surf.rst/v.surf.idw

or

r.to.vect, g.region res=30 -a, v.to.rast, r.surf.nnbathy/r.surf.idw(2)

or

r.bilinear?

Try what's best for you :).

Maciek

------------------------------------------------------------------------
CIEP?E KRAJE - CIEP?E MORZA. Szukasz atrakcyjnego wypoczynku w przyst?pnej cenie, zapoznaj si? z nasz? ofert?.
ZAPRASZAMY

www.skarpatravel.pl

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4

Maning Sambale wrote:

I have a SRTM DEM data from CGIAR (http://srtm.csi.cgiar.org/). I'm
trying to do local sea-level rise modelling.
Suppose I want it resampled to 30 meters with elevation at a
centimeters or millimeter units. Any thoughts on how to do this?

I believe the SRTM data are integer formats in meters. Converting
them to floating point does not necessaily enable you to do sub-meter
elevation calculations. Am I correct in my assumptions?

an interesting website to try:
  http://flood.firetree.net

Hamish

5

maning sambale wrote on 06/22/2006 06:41 PM:

Hi,

I have a SRTM DEM data from CGIAR (http://srtm.csi.cgiar.org/). I'm
trying to do local sea-level rise modelling.

Note that there is SRTM Version 2 out - with improvements. AFAIK
SRTM DEM data from CGIAR is based on SRTM V1, but postprocessed.

Suppose I want it resampled to 30 meters with elevation at a
centimeters or millimeter units. Any thoughts on how to do this?

Not sure if you gain anything because the vertical precision is 10m or so.

I believe the SRTM data are integer formats in meters. Converting
them to floating point does not necessaily enable you to do sub-meter
elevation calculations. Am I correct in my assumptions?

That's right. The information content doesn't change if you "just" change
the representation from integer to float. Additional information would be
needed to enrich the dataset.

Markus