| Author | Comment | Last activity | Moderation | ||
|---|---|---|---|---|---|
| cfastie | "If you want to replace the image with the questionable text "Red, Green, Blue" with one modified to include only "Red," you can find it here. I mod..." | Read more » | over 2 years ago | |||
| cfastie | "Hi Sara, Just about any handheld GPS device (e.g., Garmin) or any GPS app for a phone (I use GeoTracker) will record a track. The GPS coordinates ..." | Read more » | almost 3 years ago | |||
| cfastie | "The Plantower sensors require 4.5 to 5.5 volts. They work well with 5 volt Arduinos. They might not work properly with ESP8266 or ESP32 boards beca..." | Read more » | about 3 years ago | |||
| cfastie | "I don't know what your camera's settings were and I don't know how your camera has been modified (does it have a red filter?). I don't know what th..." | Read more » | about 3 years ago | |||
| cfastie | "I have not used a CCS-811 VOC sensor outdoors. That's mostly because I live in the woods in Vermont and the data would be boring. However the senso..." | Read more » | over 3 years ago | |||
| cfastie | "Could you possibly point me to some literature regarding this? A lag between plant stress and NDVI response is commonly reported in the remote sen..." | Read more » | over 3 years ago | |||
| cfastie | "That time lapse animation is an excellent data visualization. This makes it clear that your setup was able to control some important variables. The..." | Read more » | over 3 years ago | |||
| cfastie | "As amirberAgain says, illuminating the plants with a balance of NIR and visible light similar to sunlight will make interpretation of the NDVI resu..." | Read more » | over 3 years ago | |||
| cfastie | "An IR-cut filter is a filter that blocks most near infrared (NIR) light and passes most visible light. Most cameras have this filter installed so N..." | Read more » | over 3 years ago | |||
| cfastie | "Hi Patrick, Sorry for the delay, my Public Lab notifications go to a folder that I rarely see. You are correct that a Picavet does not work well ..." | Read more » | over 3 years ago | |||
| cfastie | "Hi Patrick, Sorry for the delay, my Public Lab notifications go to a folder that I rarely see. You are correct that a Picavet does not work well ..." | Read more » | over 3 years ago | |||
| cfastie | "Your photo is a little dark, and proper exposure is important to get meaningful NDVI results. Your photo produces reasonable NDVI results with som..." | Read more » | over 3 years ago | |||
| cfastie | "Dew point is a function of both temperature and how much moisture is in the air (humidity). In the middle of the day when it is less humid, the dew..." | Read more » | almost 4 years ago | |||
| cfastie | "The "WB 0%" photos seem to produce the most meaningful NDVI images for this subject. The photo has a pale version of the turquoise color for plant ..." | Read more » | almost 4 years ago | |||
| cfastie | "The "histogram" is a frequency distribution of brightness values (DNs, 0-255) for all of the pixels in a photo, in this case for one color channel...." | Read more » | almost 4 years ago | |||
| cfastie | "I used the standard NDVI equation. The histogram of one of the channels was probably stretched (one or more extreme points at either end removed an..." | Read more » | almost 4 years ago | |||
| cfastie | "With a red filter, photos will be bluish if the blue channel (which is used for NIR) is brighter than the red channel (which is used for VIS). For ..." | Read more » | almost 4 years ago | |||
| cfastie | "The camera does not know the color of the light that hits a pixel on the sensor. If more photons hit the pixels linked to the red channel than pixe..." | Read more » | almost 4 years ago | |||
| cfastie | "Is it by trial and error until the color of plant is like the one you provided? Yes, that would be a good way to do it. What the camera is pointed..." | Read more » | almost 4 years ago | |||
| cfastie | "What should I do to this pictures to improve the NDVI calculation? There is not much that can be done after the photo is taken to improve its abil..." | Read more » | almost 4 years ago | |||
| cfastie | "It is likely that the library that you do not want to use will provide the functionality that you are seeking. Adding these lines (and installing ..." | Read more » | almost 4 years ago | |||
| cfastie | "Brendan, That's good news. A Rosco 2007 filter was somehow attached to the lens of the RPi camera. That filter passes blue and NIR light but not mu..." | Read more » | almost 4 years ago | |||
| cfastie | "This is a great question. I don’t have much information about how these photos were made, but I will make some assumptions. I assume the Pi NoIR ca..." | Read more » | almost 4 years ago | |||
| cfastie | "If photos are taken of plants in two treatments (top and bottom) with the same camera settings (all manual control) under the exact same lighting c..." | Read more » | about 4 years ago |