# [postgis-users] SRTM Raster Geometry question

Ed Linde edolinde at gmail.com
Sun Mar 4 10:36:31 PST 2012

```Yves, I am not sure I understand what you are saying..sorry. My question is
basically if the points within a single cell can
potentially have different elevation values because of interpolation? Or do
all the points that lie within a cell get one elevation
value?

On Sun, Mar 4, 2012 at 2:36 PM, yvecai <yvecai at gmail.com> wrote:

> **
> Le 04/03/2012 14:14, Ed Linde a écrit :
>
> Hi All,
> Can someone help me understand a concept with the SRTM raster. My
> understanding is that the raster can be thought of as a uniform grid with
> each cell having dimension =  "90m x 90m" (for SRTM-1 dataset). Now I am
> just wondering if the elevation values are 4 values at each vertex or
> boundary point of a cell? or is it one elevation value for the 90x90 m^2
> area covered by the cell? I ask because if its the first option, then it
> would mean that every point that falls in the cell has it's elevation
> calculated using some sort of interpolation between the 4 corner points of
> the cell to arrive at this point's altitude. Or do several points that fall
> into this 90x90 cell get assigned the same elevation value?
> Would be great if I could get some help understanding this concept about
> SRTM rasters.
>
>  Cheers,
> Ed
>
>
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>
>  Wouldn't that be a grid of 1°/1201 by 1°/1201 with 1201x1201 elevation
> value?
> Just a guess.
> Yves
>
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