Hi all<br><br>I've
been struggling with this problem for days.. I'm trying to import a
scanned map into grass 6.1.0 on a mac. All seems to go well, until I
try and display the final raster. Here's the steps I've taken, and
thing's I've tried. <br><br>Many thanks in advance for any suggestions or advice for resolving what I suspect is a total newbie question<br><br>Pete<br>--<br><br>- create a new xy region<br>- import the image (a png scanned at 300dpi) using
r.in.gdal input=[path to scanned file] output=TL0232 location=scanTL0232
<br>- exit grass, re-launch and use region scanTL0232/PERMANENT<br>-
i.target group=TL0232 location=[real_location] mapset=PERMANENT (where
'real_location' is a pre-existing NAD83 region I want to use this
raster in)
<br>- d.mon x0<br>- d.rast TL0232_blue (as a quick test that the image imported correctly, and yes, I'm looking at a nice, high resolution image)<br>- i.points TL0232 (note that contra several of the online guides,
r.in.gdal
automatically created a group, so I didn't need to run i.group first)<br>- select a bunch of reference points, giving real-world eastings & northings, then quit i.points<br>- i.rectify -a group=TL0232 extension=_1 order=1
<br>- exit grass, re-launch and use region [real_location]/PERMANENT<br>- d.mon x0<br>- d.rast TL0232.blue_1<br><br>What
I now get is a super-low res image: 6 or 7 giant pixels to a side. If
I display other pre-existing vector layers (eg a tiger line street
map), the raster has clearly been located correctly within the region,
with the orientation and relative size I'd expect.
<br><br>For several days I assumed I was making a mistake somewhere in
the r.in.gdal / i.target / i.points / i.rectify process. However, this
morning I opened qgis to do something else, then on a whim created a
new map, displayed a couple of pre-existing vector layers from the
grass 'real_location' location, then added the grass raster layer
TL0232.blue_1. To my surprise it displayed perfectly. Correctly
oriented and rectified and in a usable resolution and everything. <br><br>Back in grass, if I do<br>- g.region rast=TL0232.blue_1<br>- d.mon x0<br>
- d.rast TL0232.blue_1<br>
<br>I get a correctly displayed raster, however as soon as I do g.region -d to go back to the (larger) default region, any attempt to display the raster again produces an unusably low-res version..<br><br>So.. What am I doing wrong? Any suggestions? Thanks again.