| Author | Comment | Last activity | Moderation | ||
|---|---|---|---|---|---|
| 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 9 years ago | |||
| nedhorning | "I'm curious why you need at least 3 bands for automated classification. I don't have a specific classification task in mind. In general I'm working..." | Read more » | over 9 years ago | |||
| nedhorning | "That's a good observation. The hotspot in these test images would tend to be toward the bottom around the shadow from Chris' head since that's wher..." | Read more » | over 9 years ago | |||
| nedhorning | "If it's sunny tomorrow I'll be out with the wood, tar paper and other things. With a little luck I'll have a research note before the end of the we..." | Read more » | over 9 years ago | |||
| nedhorning | "I got a 3" x 3" Wratten 25A gel filter on ebay for $10. There's a lot left over if you want to try it. " | Read more » | over 9 years ago | |||
| nedhorning | "Chris - It's interesting that you find that the Canon Powershots don't record much NIR in the blue channel. I found just the opposite - that the bl..." | Read more » | over 9 years ago | |||
| nedhorning | "Thanks for your comments. I am rethinking the idea that a blue filter is sensitive to chlorophyll absorption. Blue wavelengths have similar reflect..." | Read more » | over 9 years ago | |||
| nedhorning | "Thanks for the comments Chris. I would be a little cautious drawing more than very broad conclusions at this point. The reflectance values for the ..." | Read more » | over 9 years ago | |||
| nedhorning | "You could try to use some of these for calibration using Landsat imagery to estimate NDVI. " | Read more » | over 9 years ago | |||
| nedhorning | "There are gel and glass NIR-block filters that you can buy that do a pretty good job at blocking visible light. There might also be some other free..." | Read more » | over 9 years ago | |||
| nedhorning | "My guess is that you would get the same effect that you get with a blue card if you used a gray card and then multiply the blue channel by a factor..." | Read more » | over 9 years ago | |||
| nedhorning | "This white balance stuff got me thinking. I don't think the white balance actually changes the amount of light recorded by the sensor but instead m..." | Read more » | over 9 years ago | |||
| nedhorning | "With the Infrablue filter there is both visible and NIR light hitting the camera sensor and it would be helpful to know how different wavelengths a..." | Read more » | over 9 years ago | |||
| nedhorning | "Sorry for not explaining this better. We were just trying to understand which sensor channels are recording which wavelengths of light. The images ..." | Read more » | over 9 years ago | |||
| nedhorning | "Would the result improve if you set white balance using a neutral target? Concrete is pretty even across the visible and near IR. " | Read more » | over 9 years ago | |||
| nedhorning | "Well done. I've been working a bit with texture to add additional image layers (predictor variables) to the stack for eventual automated classifica..." | Read more » | almost 10 years ago | |||
| nedhorning | "Hi Charlie, The better we can represent the variability of the feature we are trying to classify the more accurate the result should be. In genera..." | Read more » | almost 10 years ago | |||
| nedhorning | "HI all, I thought I made a comment on this earlier today but apparently I did something wrong (again). It's great to see more people digging into ..." | Read more » | almost 10 years ago | |||
| nedhorning | "This isn't actually a classification. I was generating different layers from the 4-band (red, green, blue, near-IR) images collected a few weeks ag..." | Read more » | almost 10 years ago | |||
| nedhorning | "I have a feeling it is a white balance problem. The blue channel seems to be off. I would expect vegetation to be much darker in the blue channel. ..." | Read more » | almost 10 years ago | |||
| nedhorning | "Is there any interest in a video processing option in the ImageJ/Fiji plugin? " | Read more » | almost 10 years ago | |||
| nedhorning | "Increasing dynamic range will go a long way in improving NDVI results in the shadows. There are some high-dynamic-range image processing methods th..." | Read more » | about 10 years ago | |||
| nedhorning | "Great shots. The impact of shadows on NDVI will vary with the darkness of the shadow. Lower pixel values (darker shadow) will be more likely to pro..." | Read more » | about 10 years ago | |||
| nedhorning | "Hi - There used to be a "Downloads" link but I just checked and couldn't find it. I only had the source files in the Git repository. To get around..." | Read more » | over 10 years ago |