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Comments

Author Comment Last activity Moderation
nedhorning "It's worth testing but those cards you link to look promising. From my experience it's the bright target that is more of a problem than the dark ta..." | Read more » almost 3 years ago
nedhorning "Hi Jeff - I wasn't sure if you mean varying over time or over the surface. Over time both will vary but from my experience they seem fairly stable ..." | Read more » almost 3 years ago
nedhorning "Setting up and running an integrating sphere is within your reach for a 12 week course as long as the equipment is working and you have access to s..." | Read more » over 3 years ago
nedhorning "Hi dannysmith - I’m glad to hear the note was useful to get you started. I find it helpful to plot both red and blue channel regressions but I expe..." | Read more » over 3 years ago
nedhorning "For calibration I think the most important factor with white balance is that you keep it the same for an entire mission. An advantage to using the..." | Read more » over 4 years ago
nedhorning "Hi Suman, I haven't tried applying calibration coefficients in any sort of rigorous way to adjust white balance. All of my calibration work has bee..." | Read more » over 4 years ago
nedhorning "Hi Suman, I do not have a peer reviewed manuscript about this work so suggest citing this web page using a style appropriate for websites or blogs...." | Read more » over 4 years ago
nedhorning "Hi sujayj - I uploaded files with the target descriptions and reflectance information to my Google Drive: https://drive.google.com/drive/folders/0B..." | Read more » over 4 years ago
nedhorning "Hi jenjimah, Testing any of these and reporting back would be worthwhile from my perspective. One word of caution is that these are very bright re..." | Read more » over 4 years ago
nedhorning "I do not have any peer-reviewed papers related to this work - sorry. Ned " | Read more » over 4 years ago
nedhorning "The CSV file for the R script is different form the table in the "Improved DIY NIR camera calibration" post. The CSV file has the reflectance value..." | Read more » over 4 years ago
nedhorning "Hi Jeff - This should be the image. Let me know if this is ok or if I need to post it some other way Ned " | Read more » over 4 years ago
nedhorning "Hi kaushalsingh – The three target reflectance values you note seem like a good choice to me. At this point I do not have study material in additi..." | Read more » almost 5 years ago
nedhorning "Hi kaushalsingh – Ait seems as if you are trying to calibrate the image using a reference target before you calculate NDVI? If that assumption is a..." | Read more » almost 5 years ago
nedhorning "Here are a couple links that should help you get started: https://publiclab.org/wiki/infragram https://publiclab.org/notes/mlamadrid/12-08-2015/pho..." | Read more » over 5 years ago
nedhorning "Several years ago I was thinking of how to build a DIY integrating sphere/monochromator setup but never pursued it. You would want something other ..." | Read more » almost 6 years ago
nedhorning "The image for this note with the blue color was probably a JPEG image white balanced using red paper. The raw image will have much higher values in..." | Read more » about 6 years ago
nedhorning "Hi Agustin - I have a feeling the problem with with the calibration targets you are using. The targets I sued for this note were scanned by a labor..." | Read more » about 6 years ago
nedhorning "I posted it on GitHub GIST: https://gist.github.com/nedhorning/f384d9afcc043741def3 " | Read more » about 6 years ago
nedhorning "Hi - I actually thought I posted this a few days ago but for some reason I guess it didn't work. Now when I post it I see that the comments are int..." | Read more » about 6 years ago
nedhorning "Hi Jeff - I'm not sure what math you are looking for. For the gamma correction I use: The first step is to remove the effect of the gamma correcti..." | Read more » about 6 years ago
nedhorning "Chris - Thanks for pointing that out. I typically clip the values so anything greater than 1 becomes 1 and anything less than -1 become -1. " | Read more » about 6 years ago
nedhorning "Hi Agustin - Your second equation is one option. Another is: (blue- (red-blue0.8)) /(blue+(red-blue0.8)) You can play around with the factor I add..." | Read more » about 6 years ago
nedhorning "Hi Agustin, The formula you wrote is what I use. I typically use the PhotoMonitoring plugin which can be found here: https://github.com/nedhorning..." | Read more » about 6 years ago