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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
funkycbj "Krylon extra flat black spray paint is diffuse and spectrally flat across the vis-nir. A small sheet of teflon isn't too expensive and works great ..." | Read more » over 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 » over 9 years ago
funkycbj "You want to capture enough spectral variation between different surface features. If you only have 2 bands but have several classes then you may ge..." | Read more » over 9 years ago
nedhorning "I'm curious why you need at least 3 bands for automated classification. I don't have a specific classification task in mind. In general I'm working..." | Read more » over 9 years ago
funkycbj "If you take pictures at higher angles (more perpendicular and less oblique) you may achieve a more Lambertian response. Dealing more directly with ..." | Read more » over 9 years ago
nedhorning "That's a good observation. The hotspot in these test images would tend to be toward the bottom around the shadow from Chris' head since that's wher..." | Read more » over 9 years ago
funkycbj "I noticed that you are capturing your test images from an oblique angle. Bidirectional reflectance at that angle may be creating "hot spots" in you..." | Read more » over 9 years ago
nedhorning "If it's sunny tomorrow I'll be out with the wood, tar paper and other things. With a little luck I'll have a research note before the end of the we..." | Read more » over 9 years ago
cfastie "That's a much better filter for the job: It would be great to try some before all the greenery disappears. " | Read more » over 9 years ago
nedhorning "I got a 3" x 3" Wratten 25A gel filter on ebay for $10. There's a lot left over if you want to try it. " | Read more » over 9 years ago
cfastie "Oh yeah, I forgot I actually measured that, and you're right a little more NIR gets into the blue channel (I used a 735nm cutoff filter). I need to..." | Read more » over 9 years ago
nedhorning "Chris - It's interesting that you find that the Canon Powershots don't record much NIR in the blue channel. I found just the opposite - that the bl..." | Read more » over 9 years ago
cfastie "I am confused about the idea of using a red filter instead of blue in a one camera NDVI system. Is the idea to use the red channel for visible ligh..." | Read more » over 9 years ago
nedhorning "Thanks for your comments. I am rethinking the idea that a blue filter is sensitive to chlorophyll absorption. Blue wavelengths have similar reflect..." | Read more » over 9 years ago
funkycbj "A blue filter should be an acceptable alternative to a red filter when measuring vegetation if the spectral response of the blue filter is sensitiv..." | Read more » over 9 years ago
nedhorning "Thanks for the comments Chris. I would be a little cautious drawing more than very broad conclusions at this point. The reflectance values for the ..." | Read more » over 9 years ago
cfastie "Ned, This is really good data. The primary result seems to be that the calibration procedure works incredibly well. Similar NDVI results are produ..." | Read more » over 9 years ago
MicheleTobias "I may have figured out why the images have such a reduced resolution. Some of the settings in the stitching program I used limited the size of the..." | Read more » almost 12 years ago
MicheleTobias "The jury's still out on the final flying height, but I think it was about 30 meters (so really low). There is no good imagery to use to reference ..." | Read more » about 12 years ago
warren "Is there good ground reference imagery for this site? What are the coordinates? " | Read more » about 12 years ago
warren "Wow, fantastic resolution. What altitude did you fly from? " | Read more » about 12 years ago
MicheleTobias "The picture is just a piece of the final mosaic (about 7 photos shown). The whole thing was about 20 narrowed down from the 130 or so photos taken..." | Read more » about 12 years ago
gonzoearth "Well done. How large is the input dataset? I look forward to following your work. " | Read more » about 12 years ago