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<TITLE>General Questions about gdal usage with Grib1 Data Set</TITLE>
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<P DIR=LTR><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended">Hi,</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="OCR A Extended">I am new to GDal and just beginning to dig into the</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT FACE="OCR A Extended">intricacies</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended"></FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT FACE="OCR A Extended">of the library and would like some guidance on the best way to proceed.</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="OCR A Extended">I have a data set that is in a grib1 format</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended"> but with a Lambert Conformal Projection</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended">. If need be this file can be converted to either grib2 or shape file using an app</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended">lication called degrib.</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="OCR A Extended">My task is given this data-set I need to be able to extract values from the file for a given lat-lon</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended"> and don</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended">’</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended">t necessarily want to code the</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT FACE="OCR A Extended">intricacies</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended"> of the Lambert-Conformal-SP2 projection.</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended"> So in other words given a lat-lon of</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT FACE="OCR A Extended">38.59, - 97.61 I want to be able to interrogate the raster and extract a value for that given coordinate.</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="OCR A Extended">There seem to be a few options and just need advice from the season GDAL guru</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended">’</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended">s of the best way to proceed</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended">:</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="OCR A Extended">(1) </FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT FACE="OCR A Extended">Convert the lambert-conformal grib1 to a</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT FACE="OCR A Extended">cylindrical equidistant</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended"> grib1 or tiff</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended"> using gdal</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended">war</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended">p and do the</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT FACE="OCR A Extended">simpler</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended"></FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT FACE="OCR A Extended">ratio based math</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended"></FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT FACE="OCR A Extended">on the rectangular grid as opposed to the projected grid.</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="OCR A Extended">(2) </FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT FACE="OCR A Extended">Use OGRCreateCoordinateTransformation specif</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended">ying the source as Lambert Conformal and the destination as cylindrical equidistant. My presumption at this point</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended"> is that the</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT FACE="OCR A Extended">OGRCoordinateTransformation->Transform</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended">( 1, &x, &y )</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended"> method call could take a longitude as the</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT FACE="OCR A Extended">x-argument</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended">, and</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT FACE="OCR A Extended">latitude</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended"> as the</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT FACE="OCR A Extended">y-</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended">argument. A</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT FACE="OCR A Extended">successful</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended"> transform call would replace the original lat-lon with the new lat-lon and from th</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended">is point the data grid (</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended"></FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT FACE="OCR A Extended">I</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended">, J ) offsets could be calculated using simply ratios.</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN></P>
<UL DIR=LTR><UL DIR=LTR>
<P DIR=LTR><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN></P>
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<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="OCR A Extended">(3) </FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> <FONT FACE="OCR A Extended">Are they any more direct simpler ways of accomplishing the same thing? </FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"> </SPAN></P>
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<P DIR=LTR><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN></P>
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<P DIR=LTR><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"><FONT FACE="OCR A Extended">Thanks in advance for the help,</FONT></SPAN></P>
<P DIR=LTR><SPAN LANG="en-us"><FONT FACE="OCR A Extended">Bill</FONT></SPAN><SPAN LANG="en-us"></SPAN><SPAN LANG="en-us"></SPAN></P>
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