| Author | Comment | Last activity | Moderation | ||
|---|---|---|---|---|---|
| cfastie | "For some reason it's hard to find spectra of glow-in-the-dark pigments. Really, a thousand Public Lab spectrometers out there and no one has done t..." | Read more » | over 10 years ago | |||
| nathanathan | "I would like to know how glow in the dark paint compares to LEDs. Postcards with glow in the dark rainbows painted on them could be packaged with s..." | Read more » | over 10 years ago | |||
| cfastie | "Would the LED have to be placed outside the entrance slit? Otherwise the grating would form an image of the entire bulb. Standard single color LED..." | Read more » | over 10 years ago | |||
| warren | "I'm interested in something similar for spectrometer exposure calibration -- putting an LED and battery inside each spectrometer, on one side, so y..." | Read more » | over 10 years ago | |||
| nedhorning | "Hi Thorsten, Glad to hear you're making progress. When you run the plugin are you specifying that the channel from the visible image to use for th..." | Read more » | over 10 years ago | |||
| Thorsten | "Ned, I followed your advice and now have processed my first dual camera images (RGB and 850nm IR) using your PhotoMonitoring plugin, which works li..." | Read more » | over 10 years ago | |||
| mathew | "cool test! this is definitely the most pixels in a research note, as far as I've seen. " | Read more » | over 10 years ago | |||
| mathew | "I think doing calculations based on red and green might be two ways to get to the same result that Chris was seeking in his Oaktober note-- the cha..." | Read more » | over 10 years ago | |||
| warren | "It's weird because we think of green being reflective, but compared to IR, it's very absorbent. " | Read more » | over 10 years ago | |||
| cfastie | "Mathew, That does seem to be a consistent pattern. I think you are right that a green filter might offer the purest visible light channel in a sing..." | Read more » | over 10 years ago | |||
| mathew | "looking at the sensor sensitivity graph for the Nikon D200, its interesting that green is the least sensitive channel in the infrared band, implyin..." | Read more » | over 10 years ago | |||
| cfastie | "Hi Pat, The Wratten 25A is an old standard photographic filter that is still widely available in glass and gel. I think Ned bought a genuine Kodak ..." | Read more » | over 10 years ago | |||
| patcoyle | "Thanks Chris and Ned, this is an encouraging line of inquiry. Remind me on the source for the Wratten 25 filter material, or is it in the prior not..." | Read more » | over 10 years ago | |||
| nedhorning | "Is this your conclusion or do we have to test lots of other materials that commonly show up in the NDVI images we take? I have looked at a lot of..." | Read more » | over 10 years ago | |||
| nedhorning | "Chris, So many questions... I think more testing is necessary but I'll take a shot at answering each question. I'd like to hear what other folks th..." | Read more » | over 10 years ago | |||
| cfastie | "Ned, The NDVI image made from the Rosco 2008 photo by stretching the histograms is surprisingly similar to your calibrated NDVI image from the red ..." | Read more » | over 10 years ago | |||
| cfastie | "Ned, this is good evidence that some materials, like grass clippings and pine boards, will be more easily distinguished from live green plants in N..." | Read more » | over 10 years ago | |||
| nedhorning | "If you use a dual-camera setup I suggest using an unmodified camera and a NIR-pass (visible cutoff) filter for the other camera. Some people use un..." | Read more » | over 10 years ago | |||
| Thorsten | "Ned, thanks! Confusion is good in most cases! :-) I think I'll give it a try and report. For such a setup do you propose the filters you used (bl..." | Read more » | over 10 years ago | |||
| cfastie | "This is really good information. Another thing that might make red filters a good choice is that it is easier to make a red filter than an infrablu..." | Read more » | over 10 years ago | |||
| nedhorning | "Hi Thorsten, Sorry for the confusion. Some of the non-linearity between the response of the red and blue filter should be explained in the post I d..." | Read more » | over 10 years ago | |||
| Thorsten | "Dear Ned et al., I am pretty new to all this and on my way to convert my camera for NDVI mapping. After reading this post I am little confused: bl..." | Read more » | over 10 years ago | |||
| mathew | "This is great, Ned-- thanks for illustrating it with your examples. The stark difference between NDVI of dead grass in the red channel is a pretty..." | Read more » | over 10 years ago | |||
| nedhorning | "One drawback of using the red filter is that the red part of the bayer filter passes more NIR than the blue or green parts. I'm looking into ways t..." | Read more » | over 10 years ago |