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<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2>Frank,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2>Thanks for the suggestion for down
sampling....</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2>I think I am confused or trying to do too much...
this is my CLI call </FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2>gdal_translate -gcp 378.19 196.43 -76.777261 45.67899
-gcp 6013.13 282.36 -76.744739 45.678655 -gcp 5890.36 7537.81
-76.745361 45.649344 -gcp 279.98 </FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2>7464.15 -76.777866 45.649679 -scale -ot byte
-a_srs EPSG:4201 -outsize 37.5% 37.5% -mo TIFFTAG_XRESOLUTION=300 -mo
TIFFTAG_YRESOLUTION=300 -mo </FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2>"Area_or_Point = Area" A38_001.tif
oA38_001.tif</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2>however I have the same issue as I outlined in MSG
</FONT></SPAN><SPAN class=603173720-22112006><FONT size=3>[Gdal-dev]
Gdal_translate. Scaling, sizing, georeferencing</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2>the issue that I assume that after the above I should have
a geo-referenced image. Two images side by side should overlap
60%</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2>When I compare with a photo of same area processed using an
older script in Open EV the old images overlap, and the new gdal_translate
images are simply SMALLER pictures. The goal is for me to duplicate these
previously geo-refed images. Both the new and old images line up for the Upper
left corner, but then it falls apart. What happened to the other three control
points I passed it? A smaller resolution image should occupy the same physical
space, right?</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2>Some other posts have asked the same question but I never
find the answer.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2>As a final product I will be using a -outsize of
25% or 66.7% whatever resolution they come out as.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2>The solution I have come across is the
following.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2>1.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2>gdal_translate -gcp 378.19 196.43 -76.777261 45.67899
-gcp 6013.13 282.36 -76.744739 45.678655 -gcp 5890.36 7537.81
-76.745361 45.649344 -gcp 279.98 </FONT></SPAN></DIV>
<DIV><SPAN class=603173720-22112006><FONT face=Arial color=#0000ff
size=2>7464.15 -76.777866 45.649679 -scale -ot byte -a_srs
EPSG:4201 -mo "Area_or_Point = Area" A38_001.tif
oA38_001.tif</FONT></SPAN></DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<DIV><SPAN class=603173720-22112006><FONT face=Arial color=#0000ff
size=2>2.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2>gdalwarp -tr 0.0000116774 -0.0000082992 oA38_001.tif
RoA38_001.tif</FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2></FONT> </DIV>
<DIV><SPAN class=603173720-22112006><FONT face=Arial color=#0000ff size=2>For
this second stage I took info from gdalinfo of an image from step one using the
67%. I passed that image through gdalwarp without options to set the
GCP's to the UL LL etc etc. I took the resolution and multiplied in by 1.33. I
guess I am not achieving a 300 dpi image after all, but I got the file size I am
looking for.</FONT></SPAN></DIV>
<DIV><SPAN class=603173720-22112006><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=603173720-22112006><FONT face=Arial color=#0000ff size=2>So
these new resolution factors were passed again on the same image from step one
and it seemed to work. But it is messy and I can't evaluate each
photo.</FONT></SPAN></DIV>
<DIV><SPAN class=603173720-22112006><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=603173720-22112006><FONT face=Arial color=#0000ff size=2>The
end result with this two step process is a geo-refed image that is the same
size that I am trying to duplicate and matches all four
corners.</FONT></SPAN></DIV>
<DIV><SPAN class=603173720-22112006><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=603173720-22112006><FONT face=Arial color=#0000ff
size=2>Unfortunately I partialy don't realy know what all is ahppening or how I
could have predicted this outcome.</FONT></SPAN></DIV>
<DIV><SPAN class=603173720-22112006><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=603173720-22112006><FONT face=Arial color=#0000ff size=2>How
can I get to the final product quicker and cleaner?</FONT></SPAN></DIV>
<DIV><SPAN class=603173720-22112006><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=603173720-22112006><FONT face=Arial color=#0000ff size=2>Did I
goof somewhere along the way?</FONT></SPAN></DIV>
<DIV><SPAN class=603173720-22112006><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=603173720-22112006><FONT face=Arial color=#0000ff size=2>As
usual, thanks</FONT></SPAN></DIV>
<DIV><SPAN class=603173720-22112006><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=603173720-22112006><FONT face=Arial color=#0000ff
size=2>Cheers</FONT></SPAN></DIV></SPAN>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=603173720-22112006><FONT face=Arial
color=#0000ff size=2>===============</FONT><BR>If you just want to downsample
the image, you could try:<BR><BR> gdal_translate -outsize 37.5% 37.5%
in.tif out.tif<BR><BR>If you also want to override the resolution metadata tags
(possibly<BR>necessary to make printing software print properly)
try:<BR><BR> gdal_translate -outsize 37.5% 37.5%
\<BR> -mo TIFFTAG_XRESOLUTION=300 -mo
TIFFTAG_YRESOLUTION=300 \<BR> in.tif
out.tif</DIV></SPAN><SPAN
class=603173720-22112006></SPAN>========================<SPAN
class=603173720-22112006></SPAN><BR>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B> gdal-dev-bounces@lists.maptools.org
[mailto:gdal-dev-bounces@lists.maptools.org] <B>On Behalf Of </B>Sampson,
David<BR><B>Sent:</B> November 22, 2006 09:52<BR><B>To:</B>
gdal-dev@lists.maptools.org<BR><B>Subject:</B> [Gdal-dev] Gdalwarp
resolution<BR></FONT><BR></DIV>
<DIV></DIV><!-- Converted from text/rtf format -->
<P><FONT face=Arial size=2>Hey folks,</FONT> </P>
<P><FONT face=Arial size=2>I am trying to move a 800 dpi to a 300 dpi image. The
src image was created using gdal_translate to assign SRS, 4 GCP's and change
from 16bit to 8bit image. Src image has the following meta_tags</FONT></P>
<P><FONT face=Arial size=2>Metadata:</FONT> <BR><FONT face=Arial size=2>
AREA_OR_POINT=Area</FONT> <BR><FONT face=Arial size=2>
TIFFTAG_XRESOLUTION=800</FONT> <BR><FONT face=Arial size=2>
TIFFTAG_YRESOLUTION=800</FONT> <BR><FONT face=Arial size=2>
TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)</FONT> <BR><FONT face=Arial size=2>
Area_or_Point =Area </FONT></P><BR>
<P><FONT face=Arial size=2>The command line I am using is:</FONT> </P>
<P><FONT face=Arial size=2>gdalwarp -tr 300 300 oA38_001.tif
S_A38_001.tif</FONT> </P>
<P><FONT face=Arial size=2>But I get this error</FONT> </P>
<P><FONT face=Arial size=2>Creating output file that is 0P x 0L.</FONT>
<BR><FONT face=Arial size=2>ERROR 1: Attempt to create 0x0x1 TIFF file, but
width, height and bands must be positive.</FONT> </P>
<P><FONT face=Arial size=2>Any ideas?</FONT> </P></BODY></HTML>