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Multispectral imaging

The Public Lab near infrared imaging project is an open source community effort to modify consumer cameras to capture near infrared imagery for a range of purposes, including plant health. All open or accessible near infrared imaging hardware and software efforts are welcome here! **Join in by:** * Reading about goals and asking great questions * Converting a camera using one of our starter kits * Trying (and critiquing) our community-made how-to guides * Posting your own how-to guides and mods * Building on others’ work; hack and remix the kits to refine and expand them * (proposed?) Submit your improvements for inclusion in an upcoming starter kit release or add-on * (proposed?) Serve on a Research Review Group for a 3 month period ## Activities This is a list of community-generated guides for specific applications using your near-infrared imaging setup (either a camera you converted yourself with a filter pack, a ready-made near-infrared camera, or double camera setup). Some may be more reproduced -- or reproducible -- than others. Try them out to build your skills, and help improve them by leaving comments. Together, we can repeat and refine the activities into experiments. [activities:multispectral-imaging] Add your guide here Request a guide _Guides should include a materials list and a step-by-step construction guide with photo documentation. See an example._ **** ## Hardware Mods Have you added to your starter kit, improved it, or redesigned it? Show others how to take it to the next level by posting a build guide here: [upgrades:multispectral-imaging] Add your hardware modification here Request a hardware modification _Upgrades should include a parts list and a step-by-step construction guide with photo documentation. See an example._ **** ## Builds There’s a lot going on in open source near-infrared imaging -- if you’ve developed another open source design you’d like to show others how to construct, post it here! * Rasberry Pi NoIR * X * XX **** ## Choosing a tool / Starter Kits The question to start with is whether you can capture all the channels you need for your research question with a single converted camera or whether you should use a dual camera rig with one converted camera and one unconverted. That choice plays out in terms of what filter (blue or red) to use for converting your camera. Public Lab’s Kits initiative offers several starter kits, one with the basic components and instructions for converting your own digital camera to capture near-infrared imagery and a second option -- a readymade lightweight near-infrared camera. The point of the kits is to lower the barrier to capturing your own near-infrared imagery. * **The Infragram filter pack** is our least expensive way to get started with near-infrared imaging, but it does require an afternoon and some technical work to perform the camera conversion yourself. ... etc etc etc **[Visit the Infragram DIY filter pack]()** * **The Infragram point and shoot** is a Mobius camera that we worked with a factory to modify. ... etc etc etc **[Visit the Infragram Point&Shoot page](/wiki/infragram-point-shoot)** **** ## Processing near-infrared imagery Once you take a multispectral photograph with a modified camera, you must post-process it, compositing the infrared and visible data to generate a new image which (if it works) displays healthy, photosynthetically active areas as bright regions. In-depth articles on the technique by Chris Fastie can be found here: * * **** ## Software How to process your images: we're working on an easy process to generate composite, infrared + visible images that will reveal new details of plant health and photosynthesis. There are several approaches: * The **easiest way** is to process your images online at the free, open source []( * [Ned Horning's](/profile/nedhorning) [PhotoMonitoring plugin](/wiki/photo-monitoring-plugin) * Manual processing * [in Photoshop](/notes/warren/10-25-2011/video-tutorial-creating-infrared-composites-aerial-wetlands-imagery) * [or GIMP](/notes/warren/10-27-2011/video-tutorial-creating-false-color-ndvi-aerial-wetlands-imagery) * Command-line processing of single images and rendering of movies using a Python script: Source code is [here]( and here: [here]( * For those who use the webcam and have a Python interpreter, there are some image processing codes available at [Python Webcam Codes](/wiki/python-webcam-codes) * Using (deprecated) **** ## Comparison to standard tools Infrared imagery for agricultural and ecological assessment is usually captured from satellites and planes, and the information is used mainly by large farms, vineyards, and academic research projects. For example, see this illustrated [PDF, page 210]( from a commercial imagery provider who has been studying the usefulness of infrared imagery and has quotes from farmers who make use of it. There are public sources of infrared photography for the US available through the Department of Agriculture -- [NAIP]( and [Vegscape]( -- but this imagery is not collected when, as often, or at useable scale for individuals who are managing small plots. **** ## Frequently Asked Questions Ask a question about multispectral-imaging Get notified of new questions and help out [notes:question:multispectral-imaging] ...

Author Comment Last activity Moderation
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 5 years ago
dannysmith "@nedhorning thank you so kindly for all of your work, the detail you have put into it has been a tremendous help to me! I have been lucky enough to..." | Read more » over 5 years ago
stevesteve "Thanks Chris, Actually as I read more papers I am finding that many of the newer references are using: NDVI=(NIR-R)/(NIR+R) rather than the blue an..." | Read more » over 5 years ago
cfastie "I don't know of published results of studies comparing red and blue filters. Red light has been used for the visible part of the NDVI equation for ..." | Read more » over 5 years ago
warren "What if we could start by compiling some examples of interpretation (Chris has posted some great ones), and try to note what were the "givens" that..." | Read more » over 5 years ago
cfastie "Katie, it sounds like what would be helpful for you is a better NDVI wiki. That would explain what it can mean when NDVI is high, and why it might ..." | Read more » over 5 years ago
kgradow1 "This would be really helpful to me. I've struggled a lot with the infragram trying to make sense of the processed images, which has as much to do ..." | Read more » over 5 years ago
warren "Does anyone have some more photos of this conversion process we could show here, more step-by-step? " | Read more » over 5 years ago
warren "I'm collecting up info about this here: [activities:raspberry-pi-infragram] and questions about..." | Read more » over 5 years ago
warren "There's a fantastic amount of great information and guidance on this topic by @nedhorning at: ndvi-calibrate [notes:ndvi-calibrate] " | Read more » over 5 years ago
warren "Note: we now have a guide to setting white balance, although this question still stands for what the settings should actually be. https://publicla..." | Read more » over 5 years ago
cfastie "The new filter can be inside the camera or in front of the lens. If it is in front, it will get scratched and might be bent (not flat), but it is e..." | Read more » over 5 years ago
rrstrauss "@azaelb There's something I don't really get. Basically what we need to do is to remove the ir cutter from inside the camara and place the red filt..." | Read more » over 5 years ago
BettyeGagner "The differential reflection in the red and infrared (IR) bands enables you to monitor density and intensity of green vegetation growth using the sp..." | Read more » over 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 » almost 6 years ago
ccpandhare "Thanks for the amazing explanation and reference, @warren! I'll be grateful for your help @nedhorning and @warren :) " | Read more » almost 6 years ago
warren "Hi, Ned - i'm not asking about calibration at this point, just for a way to empirically test (in the sense of automated testing -- https://en.wikip..." | Read more » almost 6 years ago
Sidney_AstroPlant "Using NIR LEDs seems like a good option to look into and I'm happy to hear that I might not have to deal with extensive filtering! I just got a res..." | Read more » almost 6 years ago
cfastie "A simple option might be to turn on some NIR LEDs when the photography happens. The NIR:VIS ratio might not match sunlight, but if you know what it..." | Read more » almost 6 years ago
Sidney_AstroPlant "The kit is fully enclosed with LED with a certain blue and red ratio (I have to verify what the exact ratio is). This brings me to the conclusion t..." | Read more » almost 6 years ago
cfastie "Thanks for adding a photo. NDVI is based on the assumption that the light illuminating the foliage has a certain proportion of NIR and VIS -- the p..." | Read more » almost 6 years ago
cfastie "Using two cameras solves one of the two problems I described (mixed NIR and VIS). That problem can also be solved by measuring or making assumption..." | Read more » almost 6 years ago
Sidney_AstroPlant "Thanks Chris for your response. My assumption was that the blue filter supplied with the RPI Noir camera blocks the red channel fully. So you get a..." | Read more » almost 6 years ago
Sidney_AstroPlant "Thanks for the positive messages! I see that both of you are active in open source hardware and software initiatives. We are thinking to share our ..." | Read more » almost 6 years ago