On Wed, Sep 3, 2014 at 6:45 PM, Guillaume Pasero <[email protected]> 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] > 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. > > > > -- > <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] > > -- > -- > 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. > -- -- 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.
