[GRASSLIST:2709] i.rectify and image resolution

[ulf at mail.zmt.uni-bremen.de]

Hello Grass experts,

I hope you can help me with the following. I'm using grass 5.0.0pre2
on ix86 Linux 2.4. I have an x,y-location with a satellite (I think
Landsat-) image I received from a colleague. The region is:

 CURRENT REGION: N=1600  S=0  RES=1  ROWS=1600
		 E=1600  W=0  RES=1  COLS=1600
 PROJECTION: 0 (x,y)
 ZONE:       0

Now, I want to rectify the image. I created a target location in
lat/long-coordinate system with the highest resolution I could set,
and the "sam69" spheroid (my image is from equatorial Brazil -- is
this the right choice?). 

 CURRENT REGION: N= 0:43:48S  S=1:12:36S  RES=0:00:00.000036  ROWS=48000000
		 E=46:55:48E  W=  46:27E  RES=0:00:00.000036  COLS=48000000
 PROJECTION: 3 (Latitude-Longitude)
 ZONE:       0
 DATUM:      ** unknown (default WGS84) **
 ELLIPSOID:  sam69

Then I made an image group, set the target location, and marked points
via i.points (I have tried a set of 8-12 GPS positions of points
+-well recognizable in the image).

Afterwards, I called i.rectify. I specified "choose smallest region
that covers the image" but I was not able to set a higher resolution
than 0.01. The resulting image in the targe location has consequently
only e very rough raster: 

 CURRENT REGION: N= 0:43:48S  S=1:12:36S  RES=0:00:36  ROWS=48
		 E=46:55:48E  W=  46:27E  RES=0:00:36  COLS=48
 PROJECTION: 3 (Latitude-Longitude)
 ZONE:       0
 DATUM:      ** unknown (default WGS84) **
 ELLIPSOID:  sam69

I have no idea how to increase the resolution -- can you help me?

Many thanks, Ulf

--
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 Ulf Mehlig    <ulf.mehlig at zmt.uni-bremen.de>
               Center for Tropical Marine Ecology/ZMT, Bremen, Germany
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