That's what I usually do. I just convert my file to AAIGrid and use sed to replace the nodata to a value I like J
Bob Bob Moskovitz Seismic Hazards Mapping Program California Geological Survey 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 is strictly prohibited. From: G. Allegri [mailto:[email protected]] Sent: Monday, October 31, 2011 11:34 AM To: Moskovitz, Bob Cc: [email protected] Subject: Re: [gdal-dev] problems with calculations with very small numbers (nearzero) 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... giovanni 2011/10/31 Moskovitz, Bob <[email protected]> Hi Giovanni, I've seen -3.4028234663852886e+038 (which is a huge negative value. Your minds eye probably saw a "-" instead of "+") as a nodata value. Regards, Bob Bob Moskovitz Seismic Hazards Mapping Program California Geological Survey 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 is strictly prohibited. From: [email protected] [mailto:[email protected]] On Behalf Of G. Allegri Sent: Monday, October 31, 2011 11:19 AM To: [email protected] Subject: [gdal-dev] problems with calculations with very small numbers (nearzero) Hi, I'm having some troubles with raster algebra on a raster with very small (near zero, but not). I'm using numpy (through python gdal) to do a multiplication, eg numpy.multiply(rasterarr,2), but I obtain the following raster stats: http://pastebin.com/hHiUrWwD. 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? I've tried to do it using the LUT tag inside a VRT dataset, but it doesn't seem to do the job. giovanni
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