rotating raster maps

[Jean Prou, Ifremer DRV RA CREMA, 46.50.94.40]

>If anyone could help... I have many air photos that were scanned in as tif 
>files that were imported into GRASS as raster files. The problem is that 
>the north end of the photos were not orientated to the top of the map or 
>in this case, the top of the screen. The plan is to geo-reference these 
>images to UTM coords and to rectify the images. I have not been able to 
>find a program within GRASS that would allow me to rotate these images. 
>Does such a program exist? Or do the photos need to be scanned in with 
>north orientated to the top of the screen?
>
>Any comments would be appreciated. Thanks. 
>
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>  * DAVE BARNES                                                   *
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       Hello,

   If you have two geographical referenced points in the picture, you can
calculate the transformation (rotation,translation, scaling X and Y) of your
picture. Before the use of r.in.sunrast, let rotate and scale the picture
and bring the new image coordinate of your two points.Next, you can
incorporate the new image in GRASS. The last operation is to edit the header
of your GRASS raster to modify the insertion point ( in the cellhd directory ).

           
jean PROU
CREMA
B.P.5 
17137 L'HOUMEAU
FRANCE
TEL : 46 50 94 40
FAX : 46 50 91 60
e.mail : jean.prou at ifremer.fr