Hi Agus, To complete Julien's answer, and give you some concrete examples :
- with the new band math filter, the variable im1 will represent a vector related to the values of a pixel in each band. To make things clear : im1 = (im1b1 , im1b2, ...) In order to compute the mean value of a multi-band pixel (i.e. through all bands), the expression will simply be : mean(im1) - If you are interested in computing the mean value of a neighbourhood of pixels of a given size, and from a given band, you should use : mean(im1b2N5x5) (image #1, band #2, and neighbourhood size 5x5) - and if you want to get the global mean value of a given band, the variable im1b1Mean should help a lot. - and so on... Many other examples will be available in the cookbook soon. Among functionnalities already mentionned by Julien, you will also have a way to save your expressions and constants into a simple txt file; this, of course, will allow user to reload them into the app (or the filter) in a very simple way. Regards, Christophe. Le vendredi 5 décembre 2014 11:33:18 UTC+1, Julien Michel a écrit : > > Hi Agus, > > > We are working on an improved band math which will address many of your > comment, including stack processing, multiple outputs, neighborhood > operations, access to global stats, and improved documentation. This new > band math (called BandMathX) is already available and functional in trunk. > More info will soon appear in our blog. > > > > Regards, > > > > Julien > > > > *De :* [email protected] <javascript:> [mailto: > [email protected] <javascript:>] *De la part de* Agustin Lobo > *Envoyé :* vendredi 5 décembre 2014 09:52 > *À :* [email protected] <javascript:> > *Objet :* Re: [otb-users] Re: Band Math on image stack > > > > > > > > On Wed, Sep 3, 2014 at 6:45 PM, Guillaume Pasero <[email protected] > <javascript:>> wrote: > > Hi, > > The formula to compute the mean would look like : > "avg(im1b1,im1b2,im1b3,[...],im1b12)" > > Once you have produced the image containing the mean values, you can use > it back in the otbcli_BandMath. > Lets say you set the input image list parameter "il" to : > - first image : the 12-band initial image > - second image : the mean image > The formula for std dev. would look like : > "sqrt(avg( > (im1b1-im2b1)*(im1b1-im2b1),(im1b2-im2b1)*(im1b2-im2b1),[...],(im1b12-im2b1)*(im1b12-im2b1) > > ))" > > Regards, > Guillaume > > > > Which is very inconvenient. If you have few bands, this is feasible. If > you have 12, this is inconvenient (the proof being that you were not able > to write the whole expression in your message. With an Hyperion image, it > would be just ridiculous. > > > > I think BandMath was designed to operate among few bands, essentially to > calculate indices. Calculating stats across all bands > > would need another otbcli_ application, sort of otbcli_BandStats. Is > anything like that in the list of new features? It would be certainly most > useful. > > Agus > > > > > > > Le 03/09/2014 17:43, dcd a écrit : > > Hi Julien, > > I was just re-reading this post as it's referenced on > gis.stackexchange.com > <http://gis.stackexchange.com/questions/88996/per-pixel-statistical-calculations-on-a-raster-stack-using-gdal/111103#111103>. > > I noticed I missed something in your answer: > > On Tuesday, 11 March 2014 03:54:21 UTC-4, Julien Michel wrote: > > > 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). > > > The intent was to calculate the mean and std. dev. of a single pixel > across several layers. Ideally, I'd like to calculate the cv of each pixel. > The reply above appears to indicate that this is already possible within > OTB. If so, how would you write the expression using otbcli_BandMath given > a multilayer image (e.g., 12 bands?). > > In other words, if I had a 12 band image of average monthly temperature, > how would I calculate the mean (or std.dev., or cv) of each pixel across > several layers using otbcli_BandMath? > > Thanks! > > -- > -- > 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] > <javascript:> > To unsubscribe from this group, send email to > [email protected] <javascript:> > 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] <javascript:>. > For more options, visit https://groups.google.com/d/optout. > > > > -- > > <http://www.c-s.fr> <http://www.c-s.fr/> <http://www.c-s.fr> > > *Guillaume PASERO* > Ingénieur d'études et développement > *Business Unit E-SPACE & Geo Information* > <https://thor.si.c-s.fr/blogs/cs-blogs-business/>* - Département > APPLICATIONS* > > *CS Systèmes d'Information* > Parc de la Grande Plaine - 5, Rue Brindejonc des Moulinais - BP 15872 > 31506 Toulouse Cedex 05 - FRANCE > +33 561 17 64 21 - [email protected] <javascript:> > > -- > -- > 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] > <javascript:> > To unsubscribe from this group, send email to > [email protected] <javascript:> > 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] <javascript:>. > 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] > <javascript:> > To unsubscribe from this group, send email to > [email protected] <javascript:> > 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] <javascript:>. > 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. 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