Comments

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 » about 1 month 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 » 5 months 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 » 6 months 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 » 6 months 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 » 10 months 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 » 10 months 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 » 11 months 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 » 11 months 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 » 12 months 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 » about 1 year 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 » about 1 year 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 » about 1 year 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 » over 1 year 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 » over 1 year 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 » over 1 year 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 » over 1 year 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 » over 1 year 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 » over 1 year 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 » over 1 year 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 » over 1 year 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 » over 1 year 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 » over 1 year 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 » over 1 year 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 » over 1 year ago