Thanks again for the answers, I agree: OTB is darn quick when compared to other calculators, even getting close to/or exceeding ENVI/IDL speeds in cases.
It would be nice to call the expression directly (e.g., "std(im1b*)" or script it through bash "std($image$band)". Yes, I was looking for per-pixel calculations, but like in ENVI/IDL, it would be nice to be able to specify either per-band or per-pixel calculations. I'm learning C, but you guys will be at OTB 6 or 7 by the time I can contribute :) So, in the meantime, thanks again for the answers and for OTB! On Tue, Mar 11, 2014 at 7:54 AM, Julien Michel <[email protected]>wrote: > Hi dcd, > > To complete Jordi's answer : > > 1) Being able to output multiple bands corresponding to multiple formulas > at once, or one formula applied to many bands, is not a limitation of the > muparser library, it is a matter of implementation on the OTB side. It > would require some additional code that we ought to write someday, > considering the many feature requests we have. Until then, the solution > proposed by Jordi is just as fine (only requires a little scripting). > > 2) Regarding your second question, it depends on what you intent to > calculate : the mean and std dev of one layer, or the mean and std dev of > one pixel accross several layers ? The latter is already possible (you just > need to write the mathematical expression), while the former again requires > more code on OTB side (but it would be useful to be able to call std(im1b1) > for instance in a formula). > > Anyway, these are great ideas and OTB BandMath, simple as it is, beats a > lot of other raster bands calculators I have tried (we will never thank > enough muParser for that). This is a simple yet very discriminative feature > of OTB, so we may want to enhance it further. > > Thanks for your remarks, > > Julien > > Le 11/03/2014 04:40, dcd a écrit : > > Just out of curiousity, is this a "limitation" to using muparser for Band > Math? If so, how difficult would it be to implement a different library, > one that supports statistical operators? > > I'll look into scripting through Bash, although I'm not sure (initially) > how I might derive statistical measures that I'm interested in (e.g., cv, > std.dev), without creating a large amount of temp layers to hold > intermediary results. Oh well, perhaps I should go back to R for this task. > > Thanks for the responses. > > On Monday, March 10, 2014 8:53:16 AM UTC, Jordi Inglada wrote: >> >> dcd >> > >> > Merci, >> > >> > Two follow up questions: >> > >> > 1) Is it possible to specify all bands within a multi-layered image? >> e.g., sum(imb*)? I ask because there are times that I wish to run a raster >> calculation involving a multi-layered image with 10s or 100s of layers >> (e.g., an image >> > stack representing a time-series of temperature for every week, month, >> etc.). >> > >> > 2) Is it possible to calculate standard deviation, coefficient of >> variation, etc. using Band Math? >> > >> >> Hi, >> >> I think that the answer to both your questions is "no". At least not in >> a single command. You can however use either a shell scripts (i.e. bash) >> or a the application python bindings to write the necessary loops to do >> what you want. >> >> Jordi >> >> > Cheers! >> > >> > On Saturday, March 8, 2014 8:30:54 PM UTC, Jonathan Guinet wrote: >> > >> > Hello, >> > >> > Band Math handle multiple image and bands using imXbY where X >> refers to image number and Y refers to band numbers. >> > >> > for example if you want to calculate mean over bands of a three >> band image you can use : (im1b1+im1b2+im1b3)/3 >> > >> > 2014-03-08 15:01 GMT+01:00 dcd <[email protected]>: >> > >> > Hi OTB'ers, >> > >> > I understand how to use Band Math to accomplish calculations >> specifying single images/bands, but is there a way to do Band Math through >> a raster stack (e.g., 12 layer raster?). Also, is it possible to calculate >> the std dev, >> > cv, etc for each pixel through the stack? >> > >> > Cheers >> > >> > -- >> > -- >> > Check the OTB FAQ at >> > http://www.orfeo-toolbox.org/FAQ.html >> > >> > You received this message because you are subscribed to the >> Google >> > Groups "otb-users" group. >> > To post to this group, send email to otb-...-/ >> [email protected] >> > To unsubscribe from this group, send email to >> > [email protected] >> > For more options, visit this group at >> > http://groups.google.com/group/otb-users?hl=en >> > --- >> > You received this message because you are subscribed to the >> Google Groups "otb-users" group. >> > To unsubscribe from this group and stop receiving emails from >> it, send an email to [email protected]. >> > For more options, visit https://groups.google.com/d/optout. >> > >> > -- >> > -- >> > Check the OTB FAQ at >> > http://www.orfeo-toolbox.org/FAQ.html >> > >> > You received this message because you are subscribed to the Google >> > Groups "otb-users" group. >> > To post to this group, send email to otb-users-/JYPxA39Uh5TLH3MbocF >> [email protected] >> > To unsubscribe from this group, send email to >> > otb-users+unsubscribe-/[email protected] >> > For more options, visit this group at >> > http://groups.google.com/group/otb-users?hl=en >> > --- >> > You received this message because you are subscribed to the Google >> Groups "otb-users" group. >> > To unsubscribe from this group and stop receiving emails from it, send >> an email to otb-users+unsubscribe-/[email protected]. >> >> > For more options, visit https://groups.google.com/d/optout. >> > -- > -- > Check the OTB FAQ at > http://www.orfeo-toolbox.org/FAQ.html > > You received this message because you are subscribed to the Google > Groups "otb-users" group. > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group at > http://groups.google.com/group/otb-users?hl=en > --- > You received this message because you are subscribed to the Google Groups > "otb-users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > > For more options, visit https://groups.google.com/d/optout. > > > > -- > Julien MICHEL > CNES - DCT/SI/AP - BPI 1219 > 18, avenue Edouard Belin > 31401 Toulouse Cedex 09 - France > Tel: +33 561 282 894 - Fax: +33 561 283 109 > > -- > -- > Check the OTB FAQ at > http://www.orfeo-toolbox.org/FAQ.html > > You received this message because you are subscribed to the Google > Groups "otb-users" group. > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group at > http://groups.google.com/group/otb-users?hl=en > --- > You received this message because you are subscribed to a topic in the > Google Groups "otb-users" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/otb-users/3wG9Ss1N36E/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > For more options, visit https://groups.google.com/d/optout. > -- My public PGP key: 0xF5E746B3 -- -- -- Check the OTB FAQ at http://www.orfeo-toolbox.org/FAQ.html You received this message because you are subscribed to the Google Groups "otb-users" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/otb-users?hl=en --- You received this message because you are subscribed to the Google Groups "otb-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
