Infragram Sandbox

The [Infragram Sandbox]( is a browser based tool for experimenting with image compositing, intended for use with Public Lab [Infragram cameras](/wiki/infragram). Read [this research note](/notes/warren/08-17-2013/infragrammar-compositing-infrared-images-with-simple-mathematic-expressions#c6664) and watch this short video to get a quick idea of how to use it: ##Infragrammar Infragram Sandbox uses simple math expressions, which are actually written in JavaScript. Here are some examples: * [NDVI](/wiki/ndvi) = `(R-B)/(R+B)` for -1..1, or for 0..1 `(((R-B)/(R+B))+1)/2` in the Monochrome input * ENDVI = `((R+G)-(2*B))/((R+G)+(2*B))` which MaxMax uses for its vegetation stress cameras, in the Monochrome input * A colormapped NDVI, scaled to emphasize differentiation: `((R-B)/(R+B)-0.2)*-720`, in the Hue input, and tweaking the 0.2 value to between 0.1 and 0.9 ([read more here](/notes/warren/08-24-2013/infragrammar-with-hsv-color-model)) * (add yours here) ###Math Infragrammar can use [JavaScript math functions]( These include: * `Math.log()` - logarithms * `Math.abs()` - absolute value * `Math.sin()` - sine ###Sliders You can also link an equation to a slider; for now we are using the letter "X" to represent this value, but in the future, any string represented as {mystring} will generate a slider called "mystring". Move the slider to try different values in real time. [![infragrammar](](

Author Comment Last activity Moderation
warren "This post has some good data for blue filters!" | Read more » about 1 year ago
kauemv2 "But, only one more question before I make that post: what if i just apply the proper weights (in post-process, at the time of ndvi calculation) to ..." | Read more » about 4 years ago
cfastie " That's a good idea. Maybe someone has figured out good values for blue and red. " | Read more » about 4 years ago
kauemv2 " Many Thanks for your answer, cfastie!! So, can I ask for the question for awb_gains in another thread? " | Read more » about 4 years ago
cfastie " The NDVI result will be the same whether you use one or more layers of filter. Using two layers reduces the amount of light reaching the sensor tw..." | Read more » about 4 years ago
kanakiyab "I am also trying to figure out the exact problem. Please let me know if you have found an answer to this. Otherwise, I will have to dig deeper into..." | Read more » almost 6 years ago
cfastie "I like #4 too. I don't have a good answer for the type of glue. Something thick and quick drying. It does not have to be sticky, it just has to for..." | Read more » about 7 years ago
talha "Thank you very much for your quick and informative answer, Mr. Chris. Among those choices, which one do you suggest? To me, #4 looks ideal (light c..." | Read more » about 7 years ago
cfastie "The new filter can be put several different places: stick it on the front of the lens. Build a frame to hold it in front of the lens: https://pub..." | Read more » about 7 years ago
talha "I'm getting crazy, there is massive amount of talk about mobius conversions but there is no single guidance for converting the mobius for ndvi. I'v..." | Read more » about 7 years ago
Matthew318 "Using a heat gun allowed a clean removal of the filter, much easier than smashing. Would recommend just getting a $20 heat gun from home depot. " | Read more » about 7 years ago
RQ-05 "I will get a few more images for you to look at. It seems with this type of plant, that the HSV really jumps out at the true NIR reflectance. I am ..." | Read more » almost 8 years ago
warren "HSV is kind of a shortcut to actually making a LUT, but they're not exactly the same thing. As I mentioned in my comment on your post today, HSV ha..." | Read more » almost 8 years ago
warren "These are some good questions. We started to abandon basic HSV because it "wraps around" -- high values and low values are both "red" -- but if you..." | Read more » almost 8 years ago
RQ-05 "Is it possible to put a LUTs for the HDV? I did a few images that came out great using the HDV, and I would like to put a scale on them. Maybe I mi..." | Read more » almost 8 years ago
mathew "@Jimsford. you gotta print one! Shapeways could run one for you. " | Read more » almost 8 years ago
jimsford "where can i get that from? " | Read more » almost 8 years ago
Jimo1966 "Yes! Glue can be remove easily with Heat Gun and a Sewing Needle. Smash to bits is never an option. (or the last one) I filed down I tiny screwdriv..." | Read more » about 8 years ago
blkswanpres "You can remove the ir filter on the mobius by using a heat gun to melt the glue and screwing the unit out, you can then hit it with heat again to p..." | Read more » over 8 years ago
theowallis "My second lens arrived today and I reluctantly performed the same procedure (with a slight difference) on it. I went out and bought a glass cutter ..." | Read more » almost 9 years ago
theowallis "Yeah I'm stumped too. As you said, I can only think it's a loose element inside the remaining lens assembly. I've ordered another lens to repeat th..." | Read more » almost 9 years ago
mathew "The sensor is screwed in straight to the lens assembly, so the issue must be some other focus hardware, or a loose piece inside the lense itself. I..." | Read more » almost 9 years ago
theowallis "Nothing rattles when I shake the lens but reassembling the case (or any movement/vibration) alters the focus. I haven't installed a new filter yet...." | Read more » almost 9 years ago
cfastie "theowallis, Did you add a new filter to replace the IR block filter? Where did you put it? Do you think it is the act of tightening the set screw ..." | Read more » almost 9 years ago