Comments

Author Comment Last activity Moderation
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 » over 3 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 » about 4 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 » about 4 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 » about 5 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 » about 5 years ago
nedhorning "How about testing it on subsets of satellite imagery? You can pick the 3 bands and the band order you want for the testing and can compare that to ..." | Read more » over 5 years ago
nedhorning "Hi Jeff - I think I might be able to help with this but I'm not sure what you are looking for. NDVI is simply an algorithm applied to two bands so ..." | Read more » over 5 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 » almost 6 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 » almost 6 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 » almost 6 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 » about 6 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 » about 6 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 » about 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 » over 7 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 » over 7 years ago
nedhorning "Hi manattta - Keep in mind that white balance and calibration are two different processes. White balance is used to adjust the in-camera processing..." | Read more » almost 8 years ago
nedhorning "Hi Scott, It might be possible to calibrate a camera using a single color like a white balance card but at the very least you would need to know th..." | Read more » over 8 years ago
nedhorning "Hi Roolark - Thanks for posting your comments and sharing your research. I don't know if you can post a link to your thesis but I'd be interested ..." | Read more » over 8 years ago
nedhorning "I guess it's not actually an extra step. When I do the regression I'm comparing the JPEG pixel values that I adjusted with my inverse gamma (un)cor..." | Read more » almost 9 years ago
nedhorning "Chris, What you describe is part of what I'm trying to do. I want to take your description one step further so that the “new value” represents a p..." | Read more » almost 9 years ago
nedhorning "Hi jdburnett – It sounds like you have quite a nice collection of cameras. It would be great to run some calibration tests with different cameras a..." | Read more » almost 9 years ago
nedhorning "Chris - Here are some comments to your first round of questions: How does this apply to dual camera systems, or does it apply only to single camer..." | Read more » almost 9 years ago
nedhorning "Thanks for the suggestion. Maybe a teflon sheet is the way to go although I don't have any experience with these. Some of the thin sheets seem tran..." | Read more » about 9 years ago
nedhorning "I have been making some progress toward standardized calibration targets. Does anyone viewing this know of a source for inexpensive paints/coatings..." | Read more » about 9 years ago