Ops, you're right Bob. So the problem is the huge negative value... So the problem is how to substitute it, maybe with a more treatable value outside my raster range...<div><br></div><div>giovanni<br><div><br></div><div>
<br></div><div><br><div class="gmail_quote">2011/10/31 Moskovitz, Bob <span dir="ltr"><<a href="mailto:Bob.Moskovitz@conservation.ca.gov">Bob.Moskovitz@conservation.ca.gov</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div lang="EN-US" link="blue" vlink="purple"><div><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">Hi Giovanni,<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">I’ve seen -3.4028234663852886e+038 (which is a huge negative value. Your minds eye probably saw a “-“ instead of “+”) as a nodata value.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">Regards,<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">Bob<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:10.0pt;color:#1F497D">Bob Moskovitz<u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:10.0pt;color:#1F497D">Seismic Hazards Mapping Program<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#1F497D">California Geological Survey<u></u><u></u></span></p><p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;color:#1F497D"><u></u> <u></u></span></p>
<p class="MsoNormal" style="margin-right:0in;margin-bottom:5.0pt;margin-left:0in;text-autospace:none"><span style="font-size:8.0pt;color:navy">CONFIDENTIALITY NOTICE: This communication is intended only for the use of the individual or entity to which it is addressed. This message contains information from the State of California, California Geological Survey, which may be privileged, confidential and exempt from disclosure under applicable law, including the Electronic Communications Privacy Act. If the reader of this communication is not the intended recipient, you are hereby notified that any dissemination, distribution, or copying of this communication </span><span style="font-size:10.0pt;color:navy">is strictly prohibited.</span><span style="color:#1F497D"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><u></u> <u></u></span></p>
<div style="border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt"><div><div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in"><p class="MsoNormal"><b><span style="font-size:10.0pt">From:</span></b><span style="font-size:10.0pt"> <a href="mailto:gdal-dev-bounces@lists.osgeo.org" target="_blank">gdal-dev-bounces@lists.osgeo.org</a> [mailto:<a href="mailto:gdal-dev-bounces@lists.osgeo.org" target="_blank">gdal-dev-bounces@lists.osgeo.org</a>] <b>On Behalf Of </b>G. Allegri<br>
<b>Sent:</b> Monday, October 31, 2011 11:19 AM<br><b>To:</b> <a href="mailto:gdal-dev@lists.osgeo.org" target="_blank">gdal-dev@lists.osgeo.org</a><br><b>Subject:</b> [gdal-dev] problems with calculations with very small numbers (nearzero)<u></u><u></u></span></p>
</div></div><div><div></div><div class="h5"><p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal">Hi, <u></u><u></u></p><div><p class="MsoNormal">I'm having some troubles with raster algebra on a raster with very small (near zero, but not).<u></u><u></u></p>
<div><p class="MsoNormal">I'm using numpy (through python gdal) to do a multiplication, eg numpy.multiply(rasterarr,2), but I obtain the following raster stats: <a href="http://pastebin.com/hHiUrWwD" target="_blank">http://pastebin.com/hHiUrWwD</a>.<u></u><u></u></p>
</div><div><p class="MsoNormal"><u></u> <u></u></p></div><div><p class="MsoNormal">I suppose that -3.4028234663852886e+038 values are causing the problems, and I wonder wha'ts the best way to deal with these kind of values... Maybe rounding them to zeros?<u></u><u></u></p>
</div><div><p class="MsoNormal">I've tried to do it using the LUT tag inside a VRT dataset, but it doesn't seem to do the job.<u></u><u></u></p></div><div><p class="MsoNormal"><u></u> <u></u></p></div><div><p class="MsoNormal">
giovanni<u></u><u></u></p></div></div></div></div></div></div></div></blockquote></div><br></div></div>