Thanks for your explanation. I've changed the values to 0 as you proposed but now I get a segmentation fault when calling the GetPixel() method.
Le mardi 29 avril 2014 08:31:07 UTC+1, Rashad a écrit : > > Hi, > > > On Tue, Apr 29, 2014 at 9:17 AM, OTB Florian <[email protected]<javascript:> > > wrote: > >> Hi, >> >> 337300 and 7674920 are just the coordinates of the image origin I got >> with otbcli_ReadImageInfo command or by adding the line >> std::cout << cloudDetection->GetInput()->GetOrigin() << std::endl; >> in the code. >> > > This is wrong. You are confused with image pixels and image coordinates > here. What you are talking about is the projected coordinates of image. > > Image pixels starts with 0,0 is most image processing software. IIRC, > Matlab is an exception in this case. But anyway here if you are trying to > get the pixel for the entire image, the best thing is to use image > iterators which gives you efficient access to pixels. > > If you want to get a single pixel as you mentioned in your case. > > The image pixels starts with 0,0 and end with (width-1, height-1) > > pixelIndex[0] = 0 > pixelIndex[1] = 0 > > > And for another case if you want to get a pixel at a particular > coordinates > say you only know lat,lon -> You need to find the corresponding pixel > location based on the projection and use it. > > >> >> Le lundi 28 avril 2014 17:09:08 UTC+1, Rashad a écrit : >>> >>> Hi, >>> >>> >>> On Mon, Apr 28, 2014 at 10:49 AM, OTB Florian <[email protected]> wrote: >>> >>>> Hi Rashad, >>>> >>>> Thanks for your reply. >>>> I've tested all the examples you recommanded to me. >>>> >>>> I'm still working on the cloud detection example and always >>>> experimenting the same problem. >>>> I've just added theses code lines after cloudDetection->SetInput(reader >>>> ->GetOutput()); (l.157 : https://github.com/ >>>> echristophe/OTB/blob/master/Examples/FeatureExtraction/ >>>> CloudDetectionExample.cxx) : >>>> >>>> OutputImageType::IndexType pixelIndex; >>>> pixelIndex[0] = 337300; >>>> pixelIndex[1] = 7674920; >>>> unsigned short int pixelValue; >>>> for (int i = 0; i < 4; i++) { // cause it's a 4-band image >>>> pixelValue = cloudDetection->GetInput()->GetPixel(pixelIndex)[i]; >>>> std::cout << "GetPixel[" << i << "] = " << pixelValue << std::endl; >>>> } >>>> >>>> >>>> Then I get senseless values which are different at each execution. >>>> >>>> >>> >>> How do you find the pixelIndex in the code? >>> >>> pixelIndex[0] = 337300; >>> pixelIndex[1] = 7674920; >>> >>> Could you please elaborate the calculation of "337300" and "7674920" ? >>> >>> >>>> Any idea? >>>> >>>> Thanks in advance. >>>> >>>> >>>> Le vendredi 25 avril 2014 11:11:08 UTC+1, Rashad a écrit : >>>>> >>>>> Hi OTB, >>>>> >>>>> >>>>> On Fri, Apr 25, 2014 at 11:50 AM, OTB Florian <[email protected]>wrote: >>>>> >>>>>> >>>>>> Hi all! >>>>>> >>>>>> I'm new at OTB and studying some examples to become familiar with the >>>>>> library. >>>>>> >>>>>> >>>>> You might start with the first example - http://www.orfeo-toolbox.org/ >>>>> SoftwareGuide/SoftwareGuidech4.html >>>>> >>>>> >>>>>> I've tried the cloud detection example (https://github.com/echristoph >>>>>> e/OTB/blob/master/Examples/FeatureExtraction/CloudDetecti >>>>>> onExample.cxx) with the CloudsOnReunion.tif file and it works very >>>>>> well. >>>>>> However, I'm facing some difficulties while trying to get the values >>>>>> of the different (4) bands of a pixel via the GetPixel() method. >>>>>> >>>>> >>>>> Could you post some of your code which you tried?. >>>>> >>>>> >>>>>> I'm wondering the type returned by this method. In that case, I get >>>>>> an array with four values which don't mean anything (NaN or values >>>>>> around >>>>>> 1e-154). >>>>>> Behind this trouble is the way of encoding the band intensities. Is >>>>>> there any function to know the type of encoding, the min and max of each >>>>>> band? >>>>>> >>>>> >>>>> I think you must try the examples first. Sources are available here - >>>>> http://hg.orfeo-toolbox.org/OTB/file/fc0c18977f12/Examples/Tutorials >>>>> >>>>> [1] http://www.orfeo-toolbox.org/SoftwareGuide/SoftwareGuidech4.html >>>>> >>>>>> >>>>>> >>>>> >>>>>> If you could help me... >>>>>> >>>>>> 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. >>>>>> >>>>> >>>>> >>>>> >>>>> -- >>>>> Regards, >>>>> Rashad >>>>> >>>> -- >>>> -- >>>> 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. >>>> >>> >>> >>> >>> -- >>> Regards, >>> Rashad >>> >> -- >> -- >> 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. >> > > > > -- > Regards, > Rashad > -- -- 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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