| Author | Comment | Last activity | Moderation | ||
|---|---|---|---|---|---|
| cfastie | "Hi jeffalk, Thanks for pointing out that the PM10 index includes all particles smaller than 10µm. If that is true, you are correct that PM10 shoul..." | Read more » | over 5 years ago | |||
| cfastie | "If a device based on a Plantower sensor includes hardware that allows either live numerical display or data logging, it can be a very useful tool. ..." | Read more » | over 5 years ago | |||
| cfastie | " Writing data to eeprom will work with the limitations you outline. Adding a microSD card module and 128 MB SD card costs less than $2.00. Adding..." | Read more » | over 5 years ago | |||
| cfastie | "Thanks, I have pinged the editor. The views on this research note have doubled since December. I wonder what they would be if the link had been co..." | Read more » | over 5 years ago | |||
| cfastie | " I just noticed that Limor Fried wrote an article for Make Magazine in January citing this research note and using one of the images. An editor ask..." | Read more » | over 5 years ago | |||
| cfastie | "A full spectrum camera is one that has been converted to capture NIR by removing the IR cut filter. This filter which is present in all standard ca..." | Read more » | over 5 years ago | |||
| cfastie | "I don' t know what a "dedicated IR camera" is. You can use an appropriate red filter on a full spectrum camera to capture mostly NIR in the blue ch..." | Read more » | over 5 years ago | |||
| cfastie | " A red filter used to convert a full spectrum camera (IR cut filter removed) to an NDVI camera must pass red light and NIR light but no blue light...." | Read more » | over 5 years ago | |||
| cfastie | "Subtracting the blue channel from the red channel is a good first step for correcting for contamination of the red channel with NIR. With one parti..." | Read more » | almost 6 years ago | |||
| cfastie | " One photo every 50 shots might be sufficient. It depends on how much the light changes during that time (5 minutes?, an hour?, a day?). You might ..." | Read more » | almost 6 years ago | |||
| cfastie | " You are correct that your multi-day observation will present some problems. It is possible that doing a custom white balance on each day will comp..." | Read more » | almost 6 years ago | |||
| cfastie | "These are really nice bee images. If your goal is to make a seamless composite, the free Microsoft ICE (Windows only) will stitch the photos into a..." | Read more » | almost 6 years ago | |||
| cfastie | "The primary advantage of dual band filters is that they pass much narrower bands of wavelengths than red or blue filters (which also pass NIR). Th..." | Read more » | almost 6 years ago | |||
| cfastie | " The simplest modification to make the sketch save to SD card once per minute is to change the line: if (logData == 1) // wr..." | Read more » | almost 6 years ago | |||
| cfastie | "A few different cameras were used to take those photos. Most of the cameras were Canon PowerShots. I think all of the photos were saved by the came..." | Read more » | almost 6 years ago | |||
| cfastie | "Performing a custom white balance on a blue-filtered NIR camera fools the camera into exaggerating the brightness of the red channel. The red chann..." | Read more » | almost 6 years ago | |||
| cfastie | "It will always be difficult to know for sure to what degree the red channel is contaminated by NIR. It might be worthwhile making an estimate. For ..." | Read more » | almost 6 years ago | |||
| cfastie | "Although the absolute values you computed for NDVI are lower than they should be, it appears that your process is successfully discriminating betwe..." | Read more » | almost 6 years ago | |||
| cfastie | "Liz, it's great to know that you (or I guess your Mom) were well coiffed in the 80s, although I regret that you did not include photographic eviden..." | Read more » | almost 6 years ago | |||
| cfastie | "You are correct that both red and NIR pass through the red filter (Rosco Fire # 19) and both are captured in the red channel of the photograph. It ..." | Read more » | almost 6 years ago | |||
| cfastie | "Leslie, I will lend you anything you need. Tell me about your HEPA setup. You must already have a 5V Arduino, so all you need is three DuPont wires..." | Read more » | almost 6 years ago | |||
| cfastie | "Thanks Nick. It's good to know about the duplicate sensors. That's an intriguing engineering decision. Chris " | Read more » | almost 6 years ago | |||
| cfastie | "This photo does not look like it was taken with a mobile phone (the image quality and dynamic range are too high) and it does not look like a CD or..." | Read more » | almost 6 years ago | |||
| cfastie | "The field evaluation report linked above includes 78 graphs comparing the results of a Purple Air sensor with a $25k GRIMM optical particle counter..." | Read more » | about 6 years ago |