[GRASSLIST:10804] Re: [GRASS5] How to calculate maximum & minimum elevation across a raster?

[Michael Barton]

Brad,

Thanks for responding. Several people have offered solutions that are not
what I am looking for. So I guess I didn't explain it well enough.

Specifically, we are trying to obtain a set of coefficients that will allow
us to use a regression formula to interpolate paleoclimatic parameters
between a set of weather stations.

Empirical analysis has indicated that we can predict the needed parameters
with a high degree of accuracy in this area (W. Jordan) with a multiple
regression formula that includes coefficients for the elevation of a cell,
its geographic coordinates, its distance from the Mediterranean Sea (to the
west), the total cumulative elevation of the land between the cell and the
sea, the maximum elevation of the land between the cell and the sea, and the
minimum elevation of the land between the cell and the sea.

Using r.cost we can calculate the distance of any cell from the sea and the
cumulative elevation between the a cell and the sea. Of course we can
calculate the elevation and geographic coordinates.

The maximum and minimum elevation between a cell and the sea is a measure of
orographic barriers to moisture-bearing winds, but we can't figure out how
to create a raster map in which each cell holds the value of the maximum or
minimum elevation between the cell and the sea (to the West). So we are
stuck here, facing some kind of iterative calculation on millions of cells
that will take a long time. I'm hoping for a clever way to do this that I
haven't thought of.

Michael
__________________________________________
Michael Barton, Professor of Anthropology
School of Human Evolution and Social Change
Arizona State University
Tempe, AZ 85287-2402

phone: 480-965-6213
fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton



> From: Brad Douglas <rez at touchofmadness.com>
> Date: Tue, 07 Mar 2006 19:28:12 -0800
> To: Michael Barton <michael.barton at asu.edu>
> Subject: Re: [GRASS5] How to calculate maximum & minimum elevation across a
> raster?
> 
> On Mon, 2006-03-06 at 00:20 -0700, Michael Barton wrote:
>> I need to calculate maximum and minimum elevation between any point on
>> a landscape and a coastline. I can get total, cumulative elevation,
>> but can¹t figure out how to get maximum or minimum. Any ideas?
> 
> Michael,
> 
> Are you referring to coastal high/low/median tides?  I'm not exactly
> sure what you mean by "maximum or minimum [elevation]".
> 
> 
> -- 
> Brad Douglas <rez at touchofmadness.com>                      KB8UYR
> Address: 37.49,-121.92 / WGS84      National Map Corps #TNMC-3785
> GRASS GIS Developer
>