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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 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 8 years ago
agustin_castellano "Hi Ned me again, could be that the analisys that you did it was over the image without the red filter? because when i read the article i understand..." | Read more » about 8 years ago
agustin_castellano "Hi ned! I would like to ask you how do you setup the camera? I have a canon power shot a490 with red filter, i try to a similar test but with bud r..." | Read more » about 8 years ago
peauproductions "Hello Ned, can you please contact me: We have a new dual-band NDVI filter and would like to ask you some questions, tha..." | Read more » over 8 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 » over 8 years ago
manattta "Hi ned. Thank you for posting your work. I was wondering, and I just want to check, for flying a small UAV with a single NIR camera, with the cali..." | Read more » over 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 9 years ago
eustatic "Could i replicate this easily if i had purchased a photographers' white balance cards? would it look the same? I'm using the infragram.1.0 2-came..." | Read more » over 9 years ago
jdburnett "Roolark, Would you be willing to post a link to your thesis or some more details regarding how you manipulated RAW data? I am interested to know i..." | Read more » over 9 years ago
jdburnett "Ned, I am getting access to a spectrometer soon. I'll be in touch once I do. " | Read more » over 9 years ago
cfastie " ...the NIR reflectance of the target affects how much the red/green/blue bayer mosaic filter allows through to the sensor. Roolark, I would thin..." | Read more » over 9 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 9 years ago
Roolark "Ned, I'm not sure how much this information would help you out here, but I just finished my research thesis, which looked at the NIR sensitivity of..." | Read more » over 9 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 » over 9 years ago
cfastie "What is the additional step to get a reflectance value? You are estimating the brightness of the reflected light arriving at the camera by using a ..." | Read more » over 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 » over 9 years ago
cfastie "How close is this to what you are trying to do? NDVI depends on the difference between two values: the amount of near infrared light (in a parti..." | Read more » over 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 » over 9 years ago
cfastie "Ned, From Mary’s scans, you knew the reflectance of your colored targets for every visible and near infrared wavelength. But it looks like you used..." | Read more » over 9 years ago
jdburnett "Ned, thank you for your tremendous effort in this field. I have been following your work here and reviewing Geert Verhoeven's previous research ve..." | Read more » over 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 » over 9 years ago
cfastie "Ned, This approach looks really promising. I was writing a comment about how this fit in with our current way of making NDVI when I realized I did..." | Read more » over 9 years ago
funkycbj "Light is transmitted but it is diffusely scattered past a certain depth, which seems to be ~7mm. The minimum thickness increases with the size of ..." | Read more » almost 10 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 » almost 10 years ago