[GRASSLIST:4419] (no subject)

[Miha STAUT]

Hello,

I am almost a complete beginner in the field of Grass. I have only gone 
through some of the tutorials provided. During the learning of these basic 
concepts some questions arose.
1.
How to apply in NVIZ a different resolution from the underlying     surface 
resolution without loosing the smoothness? For example how you drape an 
ortophoto over a DEM? It seems like the program shifts to a simple Voronoi 
interpolation. Anything I tried, I got a step like surface.
2.
How can you change projection without an extensive knowledge in cartography? 
E.g. how can I change the mercator projection found in GTOPO30 to let's say 
lambert conical or delisle conical. I know Grass supports a lot of 
projections but r.proj seems to be to complicated.
3.
I have problems with exporting vector files into the Idrisi file format. The 
command performed was:
v.out.idrisi type=line in=grass_vector out=idrisi_prefix
The program complained about a "segmentation fault". I do not know what 
could that mean. I also know there are other ways of importing into Idrisi 
but I want to know how to manage it this way.
4.
How can I crop a raster image? I know for the existence of r.mask, but I 
would also like to know how to physically crop an image. Besides I do not 
know how to make with r.mask an exact window of the area of interest (e.g. 
with the definition of the border coordinates).
5.
Why Grass in some operations works in two different modes (you can choose 
between the fast but memory intensive and the slow mode), e.g. 
r.surf.contour? Other programs no matter what, work always with the same 
speed. Slow but memory non intensive mode is really very slow even with 
small rasters. If you try to choose the fast mode and you run out of memory 
it automatically switches in the slow mode. Is there anything you can do, 
not to run in neither the trouble without having to add more memory?

Regards, Miha Staut

_________________________________________________________________
MSN Photos is the easiest way to share and print your photos: 
http://photos.msn.com/support/worldwide.aspx