RE: [Tcl-nap-users] Missing values
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peter_turner
From: salah j. <s_...@ya...> - 2006-03-15 21:02:31
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Hi peter The problem was the data type , i am working with U16 so when i use NDVI the range suppose to be from -1 to 1. what was happinning is that when i subtract two numbers like thes 250 -256 i get the missing value which is 64k after that this value is used again to calculate the NDVI I.E 250 - 254 / 250+254 --------> 65536/504 Pet...@cs... wrote: RE: [Tcl-nap-users] Missing values Hi Sala, nap ndvi = 0.0/0.0 $ndvi _ This sets x to NaN (not a number) 1.0/0.0 generates Inf. The default missing value for float is NaN. You could use nap ndvi = isnan(ndvi) ? maxval : ndvi to fix the problem Cheers Peter T -----Original Message----- From: tcl...@li... [mailto:tcl...@li...] On Behalf Of salah jubeh Sent: Monday, 13 March 2006 8:32 PM To: NAP Subject: [Tcl-nap-users] Missing values Hi all While doing some image analysis i did NDVI "near-red/near+red" , some pixel values of both images has zero value thats mean (0-0)/(0-0) afetr thai i trid to get the max but i get a strange result. how can i get the max value in that case. Yahoo! Mail Bring photos to life! New PhotoMail makes sharing a breeze. --------------------------------- Yahoo! Mail Use Photomail to share photos without annoying attachments. |