[GRASSLIST:3596] Re: Help for map layer creation

[Eric G. Miller]

On Fri, Apr 26, 2002 at 07:48:24PM +0530, anil at ces.iisc.ernet.in wrote:
> Dear Sir , 
>             First of all sorry for trouble . Actually I did  according to
> your instruction . But I am not getting the correct thing .I did the
> following.
> 
> 1) Actually for test I generated a arbitary shape with v.digit .
> >From that I got a vector map "test.vect"
> 2) After this I used vect.to.rast . And I got "test.rast" map .
> 3) When I displayed "test.rast" , whole the window became white .
> 4) After that I used  'mycrop = if(test.rast,bigimage)' | r.mapcalc   
> 5) I got the map "mycrop" .
> 6) When I displayed "mycrop" , whole the window became white .
> 
> I am not able to understand what is the problem .
> 
> Please help me , when you get time .

Okay.

1.  The vector map you created has areas?  Did you build it with
v.support?  Does this vector map overlay with your raster?

2.  When you converted the vector to raster, did you make sure
the region was set appropriately?  Most raster operations only
operate within the current region settings.  This includes
v.to.rast.

Since your vector to raster conversion apparently didn't work,
the two causes would be, unbuilt vectors, or the operation
was done when the region setting did not correspond to the
input data.  Also, did you give category labels to your vectors?

P.S. please keep these discussions on the list, since it might
help others.

-- 
Eric G. Miller <egm2 at jps.net>