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Comments

Author Comment Last activity Moderation
nedhorning "NDVI uses an NIR and a Red band. Some documents have noted that instead of red you can any visible band but from my point of view that is not corre..." | Read more » about 1 month ago
nedhorning "Hi Sam, Let me know if you are still having trouble with this. I haven't used it in years but recently got a Windows computer and can see if it's ..." | Read more » 10 months ago
nedhorning "Here are a couple ways to do this. One is to use two cameras mounted as close as possible to one another with the shutter release synchronized to b..." | Read more » about 2 years ago
nedhorning " I can think of two possible reason. The most obvious would be that the illumination changed and the other is that the sensor temperature change. S..." | Read more » over 2 years ago
nedhorning "It's good you discovered that. Yesterday I started to write about the need to subtract the blue band (NIR) from the red band (red + NIR) so you get..." | Read more » over 2 years ago
nedhorning "I used this following dcraw command: dcraw -D -W -4 Image1.ORF to create this image which has been scaled to 16-bit integers: https://drive.googl..." | Read more » over 2 years ago
nedhorning " I have to run out now but will try to make time to check this in the morning. It's also possible it's due to the nature of the filter and after ca..." | Read more » over 2 years ago
nedhorning "Can you post one of your RAW images? I looked at Image1.dng and that shows the Bayer pattern so it needs to go through a debayer process to create ..." | Read more » over 2 years ago
nedhorning "I use RAW pixel values for calibration analysis and since white balance doesn't impact RAW values I don't usually worry about it. If you want to us..." | Read more » over 2 years ago
nedhorning "The calibration coefficients are, in the simplest case, the slope and y-intercept of the linear regression line for wavelength (based on calibratio..." | Read more » over 2 years ago
nedhorning " If you're using them for calibration you should be fine taking photos of the targets every so often. The calibration coefficients shouldn't change..." | Read more » over 2 years ago
nedhorning "I just read over Rob Sumner's RAW guide and see Adobe DNG Converter is free. It also looks like he did some pretty rigorous tests so my previous co..." | Read more » over 2 years ago
nedhorning "The tables look great. Before the end of the week I'll try to compare your converted image with on that I run through dcraw to see if they are simi..." | Read more » over 2 years ago
nedhorning " Hi Corymbia – It’s nice to see some new work in this area. I see that you used the Adobe DNG converter. You might want to look into that to under..." | Read more » over 2 years ago
nedhorning " Nice photos. I suggest using lighting conditions similar to those for the photos you plan to take. Once you get the white balance routine down it'..." | Read more » over 2 years ago
nedhorning "Do the images you acquire using "Auto" mode look the same or very similar to the ones you acquire using the custom white balance? " | Read more » over 2 years ago
nedhorning " Hi: It looks like you are using "Auto" mode when taking the photo. I don't have this camera but I found this web site that might help: https://sup..." | Read more » over 2 years ago
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 "Yes - the author contacted me shortly before posting the blog " | Read more » over 3 years ago
nedhorning "For the most part I am not able to reliably and accurately validate NDVI calculations. To validate results you would need to have targets with know..." | Read more » over 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 "Hi - This recent paper might be helpful: www.mdpi.com/2073-445X/6/2/38/pdf From my experience satellite based surface temperature works best over f..." | Read more » about 4 years ago