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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Hello,</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I am new to GDAL so forgive me if this issue has already
been addressed.</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I am using the GDAL AIG driver to read arcInfo grids with
values that range from 0-5.6 million. When I read one of these grids I
get the following warning from gridlib.c:</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><b><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial;font-weight:bold'>Warning 1: Unsupported Arc/Info Binary Grid
tile of type 0x20 encountered.</span></font></b></p>
<p class=MsoNormal><b><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial;font-weight:bold'>This and subsequent unsupported tile types
set to no data value.</span></font></b></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>The read does not crash my program, but it skips 10-20% of
the 4x256 pixel tiles in my image. The non-skipped tiles seem to be read
correctly. When I clip out a smaller area with a dropped tile, I get the
same problem. The grids can be read in arcInfo and arcMap with no
problems.</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Some common characteristics of these ‘bad’ blocks
as they are read in the function ‘AIGReadBlock’ are as follows:</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>nBlockSize = 4100 or 4104</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>nMagic = 32</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>nMarker = 0 (in AIGProcessBlock)</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>nMin seem to be read correctly in both good and bad blocks.</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Another clue is that the range of values in the few ‘bad’
blocks I examined is quite large (>1 million).</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Any ideas or suggestions would be appreciated. I can
also send anyone copies of the grid tiles that are not being read correctly.</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Thanks,</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>--Keith</span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font></p>
<p class=MsoNormal><font size=1 face=Courier><span style='font-size:7.5pt;
font-family:Courier'>===============================================</span></font></p>
<p class=MsoNormal><font size=1 face=Courier><span style='font-size:7.5pt;
font-family:Courier'>Keith
Olsen
/\</span></font></p>
<p class=MsoNormal><font size=1 face=Courier><span style='font-size:7.5pt;
font-family:Courier'>Oregon</span></font><font size=1 face=Courier><span
style='font-size:7.5pt;font-family:Courier'> </span></font><font size=1
face=Courier><span style='font-size:7.5pt;font-family:Courier'>State</span></font><font
size=1 face=Courier><span style='font-size:7.5pt;font-family:Courier'> </span></font><font
size=1 face=Courier><span style='font-size:7.5pt;font-family:Courier'>University</span></font><font
size=1 face=Courier><span style='font-size:7.5pt;font-family:Courier'>
/ \/\ |</span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><a href="mailto:Keith.Olsen@oregonstate.edu"><font size=1 face=Courier><span
style='font-size:7.5pt;font-family:Courier'>Keith.Olsen@oregonstate.edu</span></font></a></span></font><font
size=1 face=Courier><span style='font-size:7.5pt;font-family:Courier'>
/ \ \ ---o---</span></font></p>
<p class=MsoNormal><font size=1 face=Courier><span style='font-size:7.5pt;
font-family:Courier'>(541)
750-7279
/ || \ \</span></font></p>
<p class=MsoNormal><font size=1 face=Courier><span style='font-size:7.5pt;
font-family:Courier'>===============================================</span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> </span></font></p>
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