[GRASS-user] blank screen on displaying a raster

[Gerry James]

Javier,

I find it is helpful, when setting up the location, to leave the region extents out.  Once you have imported the raster image using r.in.gdal, set the region by g.region rast=xxx.blue.  This will ensure the bounds and pixel res are the same as the raster data set.   You should also be able to view the raster now.

Hope this helps.

Gerry James
Vancouver, BC 

-----Original Message-----
From: grassuser-bounces at grass.itc.it [mailto:grassuser-bounces at grass.itc.it] On Behalf Of javier ormeño
Sent: Saturday, November 18, 2006 6:15 PM
To: grassuser at grass.itc.it
Subject: [GRASS-user] blank screen on displaying a raster

Hi,

I`m starting to use grass 6.0.1, read the manual (of the Hannover
courses) and played with the spearfish example data (displaying rasters on 0x and viz). But i m having trouble when i try to start a new map. these are the steps I'm following:

1.- create a new location, selected x,y coordinate system, stated a description, defined the default region according to the dimensions of the images in pixels (north: 3179, east 2450, grid resolution e-w: 1 n-s 1).

2.- enter the new location as PERMANNET, import image with r.in.gdal, selecting the jpg file, naming the resulting map. hit Run, and it creates xxx.red, xxx.blue xxx.green.

3.- trouble starts from this point on, if i choose to display a raster with d.rast map=xxx.blue (starting x0 early, which works in TrueColor with 16777216 colors) nothing happens in monitor x0. next tried with display raster with rgb overlay selecting the corespondent raster previously created (red, green and blue),  hit run (a green bar fills up and displayed the above command) nothing happens, but if i use the command on the terminal "d.rgb red=xxx.red green=xxx.green blue=xxx.blue" i get
"error: Cell layer [fxxx.red] does not exsist" and nothing happens in the monitor (x0)

4.- i tried with r.composite to created a single raster from the red green and blue existing, and i checked that my location (xy
coordinates) were the same as resolution of the rasters created and same as the image (in pixels with g.region to match the raster) but it still doesn`t display the raster.
I Also tried these same steps with a new location for a tiff image, but no results in displaying the raster.

If somebody could help me out pointing put if i`m missing a step or something with a wrong command it would be very appreciated. If more information is required, please let me know.



Javier.

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