[GRASSLIST:4656] AW: White Rectangle during import of a jpg in xy Location

[Praktikant]

Thanks to all for your help,

your were right. The Region was apparently not large enough to show my map.
g.region rast=myMap solved the problem.

Richard 

-----Ursprungliche Nachricht-----
Von: Ian MacMillan [mailto:ian_macmillan at umail.ucsb.edu]
Gesendet: Dienstag, 26. Oktober 2004 21:09
An: Praktikant
Cc: GRASSLIST at baylor.edu
Betreff: Re: [GRASSLIST:4640] 


Richard,

You are getting a white rectangle because your region is not set to 
look at the colored portions of your raster.  Sounds like you imported 
a non-georeferenced map into GRASS.  If you imported this into an XY 
location, then you will have to set your region to your map with 
g.region rast=yourmap.  If you imported this directly into a region 
with georeferencing (like a UTM location), then your map will be 
hanging out somewhere around the coordinates 0,0 (since jpg's are not 
georeferenced).  If you know the bounding coordinates of your image, 
you can input that into r.support, then set your region (g.region 
rast=yourmap), and d.rast to view it.  If you don't know the 
coordinates, then import your raster into an XY location, then 
georectify it by using i.group, i.target, i.points, i.rectify.

Hope this helps,
-Ian



On Oct 26, 2004, at 12:25 AM, Praktikant wrote:

> Hello List,
>
> I would like to have an topographic map as "background" on my monitor 
> but I
> failed.
>
> I imported a jpg using r.in.gdal resulting in RGB band files 
> example.red,
> example.blue, example.green.
> When i want to check these files a white recangle in the size of the 
> file is
> shown (I would expect a red green and blue map instead so something 
> should
> be wrong in this stage already).
>
> After that i created  the statistics for the rgb-files with r.support 
> -r and
> created a color composite image from the three band files with 
> i.composite.
>
> d.rast map=example resulted in a black rectangle in the size of the 
> file.
>
> What was wrong in this process and how can I simply show a scanned map 
> on my
> screen?
>
> Thanks in advance for your help.
>
> Richard
>