Yes, what I need is to "resize" the pixel. Being the image taken from the satellite, it skews the far away pixels, mainly ones towards the edges of the bounding box. I need to execute a bow-tie correction, then somehow "compress" the pixels to a square resolution. Does that sound feasable? I will try the command.
<br><br>Cheers<br><br>Mattia<br><br><div><span class="gmail_quote">On 5/3/07, <b class="gmail_sendername">Frank Warmerdam</b> <<a href="mailto:warmerdam@pobox.com">warmerdam@pobox.com</a>> wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
mattia wrote:<br>> Coordinate System is:<br>> PROJCS["HDFLook: LINEAR",<br>> GEOGCS["unnamed",<br>> DATUM["unknown",<br>> SPHEROID["unnamed",6370997,0]],
<br>> PRIMEM["Greenwich",0],<br>> UNIT["degree",0.0174532925199433]],<br>> PROJECTION["Equirectangular"],<br>> PARAMETER["latitude_of_origin",0],
<br>> PARAMETER["central_meridian",0],<br>> PARAMETER["false_easting",0],<br>> PARAMETER["false_northing",0],<br>> UNIT["metre",1,<br>> AUTHORITY["EPSG","9001"]]]
<br>> Origin = (8912408.472916,7090227.412053 )<br>> Pixel Size = (694.49452741,-1000.15538912)<br>...<br>> Is my interpretation correct? The pixel resolution as indicated is in<br>> meters... Accordingly 694 meters horizontally (X res) , 1000 meters
<br>> vertically (Y res)?!?!<br><br>Mattia,<br><br>That is correct.<br><br>> What is the minus sign i front of the Y res for???<br><br>It means that as you step "down" the image from the top left corner you
<br>subtract 1000m per pixel step from the y coordinate. This is normal.<br><br>> What is the UNIT["degree",0.0174532925199433]], factor in this output??<br>> can I use it to define the resolution?? Or what is it needed for??
<br><br>This indicates that one degree on the underlying geographic<br>coordinate system is 0.017... radians. It is standard and does<br>not help you for what you want to do.<br><br>> Final question,<br>><br>> Is there a stright forward way of changing the image's resolution so as
<br>> to have a quadratic one whereby resX=resY ????<br><br>I didn't follow that I'm afraid. Are you just wanting to resample<br>your image to have square pixels? You could do something like:<br><br>gdalwarp -rb -ps 694 694
Area1.tif Area1SquarePixels.tif<br><br>This would use a bilinear resampling kernel to convert your<br>image from 694x1000 meter pixels to 694x694 meter pixels.<br><br>Best regards,<br>--<br>---------------------------------------+--------------------------------------
<br>I set the clouds in motion - turn up | Frank Warmerdam, <a href="mailto:warmerdam@pobox.com">warmerdam@pobox.com</a><br>light and sound - activate the windows | <a href="http://pobox.com/~warmerdam">http://pobox.com/~warmerdam
</a><br>and watch the world go round - Rush | President OSGeo, <a href="http://osgeo.org">http://osgeo.org</a><br><br></blockquote></div><br><br clear="all"><br>-- <br>Mattia