[GRASSLIST:6789] Re: kriging elevation contours

[Māris Nartišs]

Hi,

1. Have You used v.surf.rst? It gives good results for creating DTMs.
2. Vector contours can be converted to points with v.to.points. Then
v.append from GRASS wiki can be used to merge results with elevation
point data.
3. Required input data density must be determined by your self. First
think about such things:
* DTM resolution. Cell size. If You have one value per cell you don't
need a lots of data points in cell cuz they will result in only one
value.
* Input data resolution. Increasing data point count doesn't make your
data more accurate :)
* Size of resulting DTM in cells. Remember that You have limited
amount of PC resources :)

I created DTM from contour data with vertical resolution 10 m. DTM
resolution was 50x50 m. When converted contours to points, I used 100
m max distance between points. All values for RST tuning I got doing
lots of tests until result looked almost usable :)


WBR,
Maris.

On 5/13/05, wouter buytaert <wouter.buytaert at tiscali.be> wrote:
> 
> hello,
> 
> I'd like to generate a DEM from an elevation contour map using kriging
> (with the GRASS R interface and the R gdal module). However, kriging
> uses point data as input. How do I convert a vector contour map to point
> data to use for kriging? Second, and more important (but not really
> GRASS related): which is the the optimal point density (when converting
> the vector lines to points) for obtaining good results?
> 
> Thanks,
> 
> Wouter
> 
>