Revisions for GMF 2 infrared camera feature
| 12 CURRENT | mathew |
July 06, 2012 03:43
| almost 12 years ago
Jeff W/Chris F are working on this feature for the upcoming Grassroots Mapping Forum. Sourcing a lot from: http://publiclaboratory.org/wiki/dual-camera-kit-guide, images from: http://publiclaboratory.org/notes/warren/5-17-2012/infrared-camera-how-guide-gm-forum Current draftBased on input from Mathew, a shorter piece more based on introduction:
Wetlands and farm mappingOver the past two years, two distinct problems have led to the development of an inexpensive infrared camera at Public Lab. First, the desire to better understand the damage to wetland vegetation caused by the Deepwater Horizon oil spill led some of us to try to duplicate some of the sensors (infrared cameras) which are found onboard many satellites, and which are commonly used to assess vegetation health. Second, the desire of farmers to quantify plant health or stress, either to prove new, more effective organic farming practices or to reduce the use of fertilizer and thus agricultural runoff. Both scenarios also made use of our existing ability to reliably take aerial images using balloon- and kite-borne cameras. Here we'll be discussing how this works, why, and giving you a starting point to begin taking infrared photos yourself. Plant health & colorOne way to measure plant health is to compare the amount of red light reflected by foliage to the amount of infrared light reflected. Plants are green because leaves reflect green light -- they don’t use it for photosynthesis, and they also reflect almost all infrared light, which we can't see (Figure 1). Instead they use the blue and red wavelengths which are absorbed by the pigments in the leaves. The bigger the difference between the "redness" and the "infrared-ness" of the light reflected from a plant, the more the plant is photosynthesizing, and the healthier it is. The PLOTS IR camera tool allows us to compare how much red light and infrared light are reflected from plants and produce an index of how healthy or stressed the plants are (the Normalized Difference Vegetation Index or NDVI).
Hacked DIY Infrared camerasTo evaluate plant productivity, you compare an infrared photo with a regular "visible light" photo of exactly the same view. We've begun hacking cheap digital cameras by removing their "infrared block" filters, which are deep inside, right against the sensor. Canon cameras (the A490/A495 especially) are easy to modify in about 10-15 minutes, and we've published a YouTube video on the process (see links in “get involved”). We replace the IR-block filter with a piece of exposed color film negative -- just buy a fresh roll of color film, expose the whole roll by pulling it out of its canister, roll it up and have it made into negatives -- the whole thing should cost you ~$8. Then carefully cut out a clean piece (no fingerprints!) identical in size to the filter you removed and place it where you removed the IR-block filter. This will block all visible light, but is transparent to infrared light. Reassemble the camera and you can take infrared photos! (Try photographing the rest of your film negatives -- they'll be transparent to the camera!) Combining spectraThe process of combining visible and infrared spectra involves taking photos with the infrared camera and matching photos with a second, unmodified camera. Then the visible and infrared photos must be exactly aligned -- "compositing" them using Photoshop, GIMP, or automated scripts currently in development (see links in “get involved”).
Interpreting combined-spectra imagesMany factors can make a plant healthier than one growing near it: more water, more soil nutrients, fewer pests, less competition, or just the inherent ability of some species to photosynthesize more than others. Interpreting the patterns in an NDVI image can be easy when some plants are known to be stressed, but in other cases can require some understanding of the complex interactions among neighboring plants and their environment. Although there is 40 years of literature on interpreting low resolution (30 to 250 m per pixel) satellite NDVI images, the high resolution (3 to 15 cm per pixel) images possible with our IR camera tool could provide novel insights into fine-scale vegetation patterns. We are still learning how to extract meaningful information from these NDVI images and look forward to getting feedback about how to do this. We are currently working on interpreting the results of a balloon mapping flight over some cover crop trials in New Hampshire. In the example images below the rectangular plots received different nutrient or management treatments, and both the normal black and white photo and the NDVI image reveal that plants responded differently to some treatments.
Contributors welcome!Our work is far from complete -- many steps are difficult or time consuming, and we need your help to:
Get InvolvedTo learn more and get involved, see: http://publiclaboratory.org/tool/near-infrared-camera (a page which needs revision) http://publiclaboratory.org/wiki/dual-camera-kit-guide (a newer page which could be merged with the above) Older, longer outlineSix small features organized around a central large graphic (see above sketch) on an approx 11x17 area. 1. Science background
2. A second camera to capture NIR
3. Triggering the cameras in flight
4. Matching and compositing images
Advanced: To produce more precise results (link to web page):
5. Interpretation
6. Conclusion
|
Revert | |
| 11 | warren |
July 05, 2012 17:23
| almost 12 years ago
Jeff W/Chris F are working on this feature for the upcoming Grassroots Mapping Forum. Sourcing a lot from: http://publiclaboratory.org/wiki/dual-camera-kit-guide, images from: http://publiclaboratory.org/notes/warren/5-17-2012/infrared-camera-how-guide-gm-forum Current draftBased on input from Mathew, a shorter piece more based on introduction:
Wetlands and farm mappingOver the past two years, two distinct problems have led to the development of an inexpensive infrared camera at Public Lab. First, the desire to better understand the damage to wetland vegetation caused by the Deepwater Horizon oil spill led some of us to try to duplicate some of the sensors (infrared cameras) which are found onboard many satellites, and which are commonly used to assess vegetation health. Second, the desire of farmers to quantify plant health or stress, either to prove new, more effective organic farming practices or to reduce the use of fertilizer and thus agricultural runoff. Both scenarios also made use of our existing ability to reliably take aerial images using balloon- and kite-borne cameras. Here we'll be discussing how this works, why, and giving you a starting point to begin taking infrared photos yourself. Plant health & colorOne way to measure plant health is to compare the amount of red light reflected by foliage to the amount of infrared light reflected. Plants are green because leaves reflect green light -- they don’t use it for photosynthesis, and they also reflect almost all infrared light, which we can't see (Figure 1). Instead they use the blue and red wavelengths which are absorbed by the pigments in the leaves. The bigger the difference between the "redness" and the "infrared-ness" of the light reflected from a plant, the more the plant is photosynthesizing, and the healthier it is. The PLOTS IR camera tool allows us to compare how much red light and infrared light are reflected from plants and produce an index of how healthy or stressed the plants are (the Normalized Difference Vegetation Index or NDVI).
Hacked DIY Infrared camerasTo evaluate plant productivity, you compare an infrared photo with a regular "visible light" photo of exactly the same view. We've begun hacking cheap digital cameras by removing their "infrared block" filters, which are deep inside, right against the sensor. Canon cameras (the A490/A495 especially) are easy to modify in about 10-15 minutes, and we've published a YouTube video on the process (see links below). We replace the IR-block filter with a piece of exposed color film negative -- just buy a fresh roll of color film, expose the whole roll by pulling it out of its canister, roll it up and have it made into negatives -- the whole thing should cost you ~$8. Then carefully cut out a clean piece (no fingerprints!) identical in size to the filter you removed and place it where you removed the IR-block filter. This will block all visible light, but is transparent to infrared light. Reassemble the camera and you can take infrared photos! (Try photographing the rest of your film negatives -- they'll be transparent to the camera!) Combining images from two camerasThe process involves taking photos with the infrared camera and matching photos with a second, unmodified camera. Then the visible and infrared photos must be exactly aligned -- "compositing" them using Photoshop, GIMP, or automated scripts currently in development (see links below).
InterpretationMany factors can make a plant healthier than one growing near it: more water, more soil nutrients, fewer pests, less competition, or just the inherent ability of some species to photosynthesize more than others. Interpreting the patterns in an NDVI image can be easy when some plants are known to be stressed, but in other cases can require some understanding of the complex interactions among neighboring plants and their environment. Although there is 40 years of literature on interpreting low resolution (30 to 250 m per pixel) satellite NDVI images, the high resolution (3 to 15 cm per pixel) images possible with our IR camera tool could provide novel insights into fine-scale vegetation patterns. We are still learning how to extract meaningful information from these NDVI images and look forward to getting feedback about how to do this. We are currently working on interpreting the results of a balloon mapping flight over some cover crop trials in New Hampshire. In the example images below the rectangular plots received different nutrient or management treatments, and both the normal black and white photo and the NDVI image reveal that plants responded differently to some treatments.
Contributors welcome!Our work is far from complete -- many steps are difficult or time consuming, and we need your help to:
To learn more and get involved, see: http://publiclaboratory.org/tool/near-infrared-camera (a page which needs revision) http://publiclaboratory.org/wiki/dual-camera-kit-guide (a newer page which could be merged with the above) Older, longer outlineSix small features organized around a central large graphic (see above sketch) on an approx 11x17 area. 1. Science background
2. A second camera to capture NIR
3. Triggering the cameras in flight
4. Matching and compositing images
Advanced: To produce more precise results (link to web page):
5. Interpretation
6. Conclusion
|
Revert | |
| 10 | cfastie |
July 03, 2012 19:10
| almost 12 years ago
Jeff W/Chris F are working on this feature for the upcoming Grassroots Mapping Forum. Sourcing a lot from: http://publiclaboratory.org/wiki/dual-camera-kit-guide, images from: http://publiclaboratory.org/notes/warren/5-17-2012/infrared-camera-how-guide-gm-forum Current draftBased on input from Mathew, a shorter piece more based on introduction:
Wetlands and farm mappingPlant health & colorOne way to measure plant health is to compare the amount of red light reflected by foliage to the amount of infrared light reflected. Plants are green because leaves reflect green light -- they don’t use it for photosynthesis, and they also reflect almost all infrared light, which we can't see (Figure 1). Instead they use the blue and red wavelengths which are absorbed by the pigments in the leaves. The bigger the difference between the "redness" and the "infrared-ness" of the light reflected from a plant, the more the plant is photosynthesizing, and the healthier it is. The PLOTS IR camera tool allows us to compare how much red light and infrared light are reflected from plants and produce an index of how healthy or stressed the plants are (the Normalized Difference Vegetation Index or NDVI).
Hacked DIY Infrared camerasTo evaluate plant productivity, you compare an infrared photo with a regular "visible light" photo of exactly the same view. We've begun hacking cheap digital cameras by removing their "infrared block" filters, which are deep inside, right against the sensor. Canon cameras (the A490/A495 especially) are easy to modify in about 10-15 minutes, and we've published a YouTube video on the process (see links below). We replace the IR-block filter with a piece of exposed color film negative -- just buy a fresh roll of color film, expose the whole roll by pulling it out of its canister, roll it up and have it made into negatives -- the whole thing should cost you ~$8. Then carefully cut out a clean piece (no fingerprints!) identical in size to the filter you removed and place it where you removed the IR-block filter. This will block all visible light, but is transparent to infrared light. Reassemble the camera and you can take infrared photos! (Try photographing the rest of your film negatives -- they'll be transparent to the camera!) Combining images from two camerasThe process involves taking photos with the infrared camera and matching photos with a second, unmodified camera. Then the visible and infrared photos must be exactly aligned -- "compositing" them using Photoshop, GIMP, or automated scripts currently in development (see links below).
InterpretationMany factors can make a plant healthier than one growing near it: more water, more soil nutrients, fewer pests, less competition, or just the inherent ability of some species to photosynthesize more than others. Interpreting the patterns in an NDVI image can be easy when some plants are known to be stressed, but in other cases can require some understanding of the complex interactions among neighboring plants and their environment. Although there is 40 years of literature on interpreting low resolution (30 to 250 m per pixel) satellite NDVI images, the high resolution (3 to 15 cm per pixel) images possible with our IR camera tool could provide novel insights into fine-scale vegetation patterns. We are still learning how to extract meaningful information from these NDVI images and look forward to getting feedback about how to do this. We are currently working on interpreting the results of a balloon mapping flight over some cover crop trials in New Hampshire. In the example images below the rectangular plots received different nutrient or management treatments, and both the normal black and white photo and the NDVI image reveal that plants responded differently to some treatments.
Contributors welcome!Our work is far from complete -- many steps are difficult or time consuming, and we need your help to:
To learn more and get involved, see: http://publiclaboratory.org/tool/near-infrared-camera (a page which needs revision) http://publiclaboratory.org/wiki/dual-camera-kit-guide (a newer page which could be merged with the above) Older, longer outlineSix small features organized around a central large graphic (see above sketch) on an approx 11x17 area. 1. Science background
2. A second camera to capture NIR
3. Triggering the cameras in flight
4. Matching and compositing images
Advanced: To produce more precise results (link to web page):
5. Interpretation
6. Conclusion
|
Revert | |
| 9 | cfastie |
July 03, 2012 16:23
| almost 12 years ago
Jeff W/Chris F are working on this feature for the upcoming Grassroots Mapping Forum. Sourcing a lot from: http://publiclaboratory.org/wiki/dual-camera-kit-guide, images from: http://publiclaboratory.org/notes/warren/5-17-2012/infrared-camera-how-guide-gm-forum Current draftBased on input from Mathew, a shorter piece more based on introduction:
Wetlands and farm mappingPlant health & colorOne way to measure plant health is to compare the amount of red light reflected by foliage to the amount of infrared light reflected. Plants are green because leaves reflect green light -- they don’t use it for photosynthesis, and they also reflect almost all infrared light (Figure 1). Instead they use the blue and red wavelengths which are absorbed by the pigments in the leaves. The bigger the difference between the "redness" and the "infrared-ness" of the light reflected from a plant, the more the plant is photosynthesizing, and the healthier it is. The PLOTS IR camera tool allows us to compare how much red light and infrared light are reflected from plants and produce an index of how healthy or stressed the plants are.
Hacked DIY Infrared camerasTo measure photosynthesis, then, you can compare an infrared photo with a regular "visible light" photo of exactly the same view. We've begun hacking cheap digital cameras by removing their "infrared block" filters, which are deep inside, right against the sensor. Canon cameras (the A490/A495 especially) are easy to modify in about 10-15 minutes, and we've published a YouTube video on the process (see links below). We replace the IR-block filter with a piece of exposed color film negative -- just buy a fresh roll of color film, expose the whole roll by pulling it out of its canister, roll it up and have it made into negatives -- the whole thing should cost you ~$8. Then carefully cut out a clean piece (no fingerprints!) identical in size to the filter you removed and place it where you removed the IR-block filter. This will block all visible light, but is transparent to infrared light. Reassemble the camera and you can take infrared photos! (Try photographing the rest of your film negatives -- they'll be transparent to the camera!) Combining images from two camerasSince infrared light is invisible to us, we have to use a different color -- red -- to represent it. More importantly, you need to take matching photos with a second, unmodified camera, and exactly align the visible and infrared photos -- "compositing" them with Photoshop, GIMP, or automated scripts currently in development (see links below).
InterpretationMany factors can make a plant healthier than one growing near it: more water, more soil nutrients, fewer pests, less competition, or just the inherent ability of some species to photosynthesize more than others. Interpreting the patterns in an NDVI image can be easy when some plants are known to be stressed, but in other cases can require some understanding of the complex interactions among neighboring plants and their environment. Although there is 40 years of literature on interpreting low resolution (30 to 250 m per pixel) NDVI images from satellites, the high resolution (3 to 15 cm per pixel) images possible with our IR camera tool could provide novel insights into fine-scale vegetation patterns. We are still learning how to extract meaningful information from these NDVI images and look forward to getting feedback about how to do this. We are currently working on interpreting the results of a balloon mapping flight over come cover crop trials in New Hampshire. In the example images below the rectangular plots received different nutrient or management treatments, and both the normal black and white photo and the monochrome NDVI image reveal that plants responded differently to some treatments.
Contributors welcome!Our work is far from complete -- many steps are difficult or time consuming, and we need your help to:
To learn more and get involved, see: http://publiclaboratory.org/tool/near-infrared-camera (a page which needs revision) http://publiclaboratory.org/wiki/dual-camera-kit-guide (a newer page which could be merged with the above) Older, longer outlineSix small features organized around a central large graphic (see above sketch) on an approx 11x17 area. 1. Science background
2. A second camera to capture NIR
3. Triggering the cameras in flight
4. Matching and compositing images
Advanced: To produce more precise results (link to web page):
5. Interpretation
6. Conclusion
|
Revert | |
| 8 | cfastie |
July 03, 2012 15:57
| almost 12 years ago
Jeff W/Chris F are working on this feature for the upcoming Grassroots Mapping Forum. Sourcing a lot from: http://publiclaboratory.org/wiki/dual-camera-kit-guide, images from: http://publiclaboratory.org/notes/warren/5-17-2012/infrared-camera-how-guide-gm-forum Current draftBased on input from Mathew, a shorter piece more based on introduction:
Wetlands and farm mappingPlant health & colorOne way to measure plant health is to compare the amount of red light reflected by foliage to the amount of infrared light reflected. Plants are green because leaves reflect green light -- they don’t use it for photosynthesis, and they also reflect almost all infrared light (Figure 1). Instead they use the blue and red wavelengths which are absorbed by the pigments in the leaves. The bigger the difference between the "redness" and the "infrared-ness" of the light reflected from a plant, the more the plant is photosynthesizing, and the healthier it is. The PLOTS IR camera tool allows us to compare how much red light and infrared light are reflected from plants and produce an index of how healthy or stressed the plants are.
Hacked DIY Infrared camerasTo measure photosynthesis, then, you can compare an infrared photo with a regular "visible light" photo of exactly the same view. We've begun hacking cheap digital cameras by removing their "infrared block" filters, which are deep inside, right against the sensor. Canon cameras (the A490/A495 especially) are easy to modify in about 10-15 minutes, and we've published a YouTube video on the process (see links below). We replace the IR-block filter with a piece of exposed color film negative -- just buy a fresh roll of color film, expose the whole roll by pulling it out of its canister, roll it up and have it made into negatives -- the whole thing should cost you ~$8. Then carefully cut out a clean piece (no fingerprints!) identical in size to the filter you removed and place it where you removed the IR-block filter. This will block all visible light, but is transparent to infrared light. Reassemble the camera and you can take infrared photos! (Try photographing the rest of your film negatives -- they'll be transparent to the camera!) Combining images from two camerasSince infrared light is invisible to us, we have to use a different color -- red -- to represent it. More importantly, you need to take matching photos with a second, unmodified camera, and exactly align the visible and infrared photos -- "compositing" them with Photoshop, GIMP, or automated scripts currently in development (see links below).
InterpretationMany factors can make a plant healthier than one growing near it: more water, more soil nutrients, fewer pests, less competition, or just the inherent ability of some species to photosynthesize more than others. Interpreting the patterns in an NDVI image can be easy when some plants are known to be stressed, but in other cases can require some understanding of the complex interactions among neighboring plants and their environment. Although there is 40 years of literature on interpreting low resolution (30 to 250 m per pixel) NDVI images from satellites, the high resolution (3 to 15 cm per pixel) images possible with our IR camera tool could provide novel insights into fine-scale vegetation patterns. Contributors welcome!Our work is far from complete -- many steps are difficult or time consuming, and we need your help to:
To learn more and get involved, see: http://publiclaboratory.org/tool/near-infrared-camera (a page which needs revision) http://publiclaboratory.org/wiki/dual-camera-kit-guide (a newer page which could be merged with the above) Older, longer outlineSix small features organized around a central large graphic (see above sketch) on an approx 11x17 area. 1. Science background
2. A second camera to capture NIR
3. Triggering the cameras in flight
4. Matching and compositing images
Advanced: To produce more precise results (link to web page):
5. Interpretation
6. Conclusion
|
Revert | |
| 7 | cfastie |
July 03, 2012 14:37
| almost 12 years ago
Jeff W/Chris F are working on this feature for the upcoming Grassroots Mapping Forum. Sourcing a lot from: http://publiclaboratory.org/wiki/dual-camera-kit-guide, images from: http://publiclaboratory.org/notes/warren/5-17-2012/infrared-camera-how-guide-gm-forum Current draftBased on input from Mathew, a shorter piece more based on introduction:
Wetlands and farm mappingPlant health & colorOne way to measure plant health is to compare the amount of red light reflected by foliage to the amount of infrared light reflected. Plants are green because leaves reflect green light -- they don’t use it for photosynthesis, and they also reflect almost all infrared light (Figure 1). Instead they use the blue and red wavelengths which are absorbed by the pigments in the leaves. The bigger the difference between the "redness" and the "infrared-ness" of the light reflected from a plant, the more the plant is photosynthesizing, and the healthier it is. The PLOTS IR camera tool allows us to compare how much red light and infrared light are reflected from plants and produce an index of how healthy or stressed the plants are.
Hacked DIY Infrared camerasTo measure photosynthesis, then, you can compare an infrared photo with a regular "visible light" photo of exactly the same view. We've begun hacking cheap digital cameras by removing their "infrared block" filters, which are deep inside, right against the sensor. Canon cameras (the A490/A495 especially) are easy to modify in about 10-15 minutes, and we've published a YouTube video on the process (see links below). We replace the IR-block filter with a piece of exposed color film negative -- just buy a fresh roll of color film, expose the whole roll by pulling it out of its canister, roll it up and have it made into negatives -- the whole thing should cost you ~$8. Then carefully cut out a clean piece (no fingerprints!) identical in size to the filter you removed and place it where you removed the IR-block filter. This will block all visible light, but is transparent to infrared light. Reassemble the camera and you can take infrared photos! (Try photographing the rest of your film negatives -- they'll be transparent to the camera!) Combining images from two camerasSince infrared light is invisible to us, we have to use a different color -- red -- to represent it. More importantly, you need to take matching photos with a second, unmodified camera, and exactly align the visible and infrared photos -- "compositing" them with Photoshop, GIMP, or automated scripts currently in development (see links below).
InterpretationMany factors can make a plant healthier than one growing next to it: more water, more soil nutrients, fewer pests, less competition, or just the inherent ability of some species to photosynthesize more than others. Contributors welcome!Our work is far from complete -- many steps are difficult or time consuming, and we need your help to:
To learn more and get involved, see: http://publiclaboratory.org/tool/near-infrared-camera (a page which needs revision) http://publiclaboratory.org/wiki/dual-camera-kit-guide (a newer page which could be merged with the above) Older, longer outlineSix small features organized around a central large graphic (see above sketch) on an approx 11x17 area. 1. Science background
2. A second camera to capture NIR
3. Triggering the cameras in flight
4. Matching and compositing images
Advanced: To produce more precise results (link to web page):
5. Interpretation
6. Conclusion
|
Revert | |
| 6 | warren |
June 29, 2012 13:32
| almost 12 years ago
Jeff W/Chris F are working on this feature for the upcoming Grassroots Mapping Forum. Sourcing a lot from: http://publiclaboratory.org/wiki/dual-camera-kit-guide, images from: http://publiclaboratory.org/notes/warren/5-17-2012/infrared-camera-how-guide-gm-forum Current draftBased on input from Mathew, a shorter piece more based on introduction:
Wetlands and farm mappingPlant health & colorAs it turns out, one way to measure plant stress is to compare the amount of red light reflected by plants to the amount of infrared light they reflect. Vegetation is green because plant leaves reflect green light -- they don’t use it for photosynthesis (Figure 1). Instead they use almost all of the blue and red wavelengths in sunlight. So the bigger the difference between the "redness" and the "infrared-ness", the more a plant is photosynthesizing, and the healthier it is. "Remote sensing" literature has also found correlations between high infrared and specific deficiencies, such as lack of nitrogen, ..... (cite)
Hacked DIY Infrared camerasTo measure photosynthesis, then, you can compare an infrared photo with a regular "visible light" photo of exactly the same view. We've begun hacking cheap digital cameras by removing their "infrared block" filters, which are deep inside, right against the sensor. Canon cameras (the A490/A495 especially) are easy to modify in about 10-15 minutes, and we've published a YouTube video on the process (see links below). We replace the IR-block filter with a piece of exposed color film negative -- just buy a fresh roll of color film, expose the whole roll by pulling it out of its canister, roll it up and have it made into negatives -- the whole thing should cost you ~$8. Then carefully cut out a clean piece (no fingerprints!) identical in size to the filter you removed and place it where you removed the IR-block filter. This will block all visible light, but is transparent to infrared light. Reassemble the camera and you can take infrared photos! (Try photographing the rest of your film negatives -- they'll be transparent to the camera!) Combining images from two camerasSince infrared light is invisible to us, we have to use a different color -- red -- to represent it. More importantly, you need to take matching photos with a second, unmodified camera, and exactly align the visible and infrared photos -- "compositing" them with Photoshop, GIMP, or automated scripts currently in development (see links below).
Interpretation...soon Contributors welcome!Our work is far from complete -- many steps are difficult or time consuming, and we need your help to:
To learn more and get involved, see: http://publiclaboratory.org/tool/near-infrared-camera (a page which needs revision) http://publiclaboratory.org/wiki/dual-camera-kit-guide (a newer page which could be merged with the above) Older, longer outlineSix small features organized around a central large graphic (see above sketch) on an approx 11x17 area. 1. Science background
2. A second camera to capture NIR
3. Triggering the cameras in flight
4. Matching and compositing images
Advanced: To produce more precise results (link to web page):
5. Interpretation
6. Conclusion
|
Revert | |
| 5 | warren |
June 29, 2012 13:31
| almost 12 years ago
Jeff W/Chris F are working on this feature for the upcoming Grassroots Mapping Forum. Sourcing a lot from: http://publiclaboratory.org/wiki/dual-camera-kit-guide, images from: http://publiclaboratory.org/notes/warren/5-17-2012/infrared-camera-how-guide-gm-forum Current draftBased on input from Mathew, a shorter piece more based on introduction:
Wetlands and farm mappingPlant health & colorAs it turns out, one way to measure plant stress is to compare the amount of red light reflected by plants to the amount of infrared light they reflect. Vegetation is green because plant leaves reflect green light -- they don’t use it for photosynthesis (Figure 1). Instead they use almost all of the blue and red wavelengths in sunlight. So the bigger the difference between the "redness" and the "infrared-ness", the more a plant is photosynthesizing, and the healthier it is. "Remote sensing" literature has also found correlations between high infrared and specific deficiencies, such as lack of nitrogen, ..... (cite)
Hacked DIY Infrared camerasTo measure photosynthesis, then, you can compare an infrared photo with a regular "visible light" photo of exactly the same view. We've begun hacking cheap digital cameras by removing their "infrared block" filters, which are deep inside, right against the sensor. Canon cameras (the A490/A495 especially) are easy to modify in about 10-15 minutes, and we've published a YouTube video on the process (see links below). We replace the IR-block filter with a piece of exposed color film negative -- just buy a fresh roll of color film, expose the whole roll by pulling it out of its canister, roll it up and have it made into negatives -- the whole thing should cost you ~$8. Then carefully cut out a clean piece (no fingerprints!) identical in size to the filter you removed and place it where you removed the IR-block filter. This will block all visible light, but is transparent to infrared light. Reassemble the camera and you can take infrared photos! (Try photographing the rest of your film negatives -- they'll be transparent to the camera!) Combining images from two camerasSince infrared light is invisible to us, we have to use a different color -- red -- to represent it. More importantly, you need to take matching photos with a second, unmodified camera, and exactly align the visible and infrared photos -- "compositing" them with Photoshop, GIMP, or automated scripts currently in development (see links below).
Interpretation...soon Contributors welcome!Our work is far from complete -- many steps are difficult or time consuming, and we need your help to:
To learn more and get involved, see: http://publiclaboratory.org/tool/near-infrared-camera (a page which needs revision) http://publiclaboratory.org/wiki/dual-camera-kit-guide (a newer page which could be merged with the above) Older, longer outlineSix small features organized around a central large graphic (see above sketch) on an approx 11x17 area. 1. Science background
2. A second camera to capture NIR
3. Triggering the cameras in flight
4. Matching and compositing images
Advanced: To produce more precise results (link to web page):
5. Interpretation
6. Conclusion
|
Revert | |
| 4 | warren |
June 28, 2012 13:38
| almost 12 years ago
Jeff W/Chris F are working on this feature for the upcoming Grassroots Mapping Forum. Sourcing a lot from: http://publiclaboratory.org/wiki/dual-camera-kit-guide, images from: http://publiclaboratory.org/notes/warren/5-17-2012/infrared-camera-how-guide-gm-forum Current draftBased on input from Mathew, a shorter piece more based on introduction: Wetlands and farm mappingPlant health & colorAs it turns out, one way to measure plant stress is to compare the amount of red light reflected by plants to the amount of infrared light they reflect. Vegetation is green because plant leaves reflect green light -- they don’t use it for photosynthesis (Figure 1). Instead they use almost all of the blue and red wavelengths in sunlight. So the bigger the difference between the "redness" and the "infrared-ness", the more a plant is photosynthesizing, and the healthier it is. "Remote sensing" literature has also found correlations between high infrared and specific deficiencies, such as lack of nitrogen, ..... (cite)
Hacked DIY Infrared camerasTo measure photosynthesis, then, you can compare an infrared photo with a regular "visible light" photo of exactly the same view. We've begun hacking cheap digital cameras by removing their "infrared block" filters, which are deep inside, right against the sensor. Canon cameras (the A490/A495 especially) are easy to modify in about 10-15 minutes, and we've published a YouTube video on the process (see links below). We replace the IR-block filter with a piece of exposed color film negative -- just buy a fresh roll of color film, expose the whole roll by pulling it out of its canister, roll it up and have it made into negatives -- the whole thing should cost you ~$8. Then carefully cut out a clean piece (no fingerprints!) identical in size to the filter you removed and place it where you removed the IR-block filter. This will block all visible light, but is transparent to infrared light. Reassemble the camera and you can take infrared photos! (Try photographing the rest of your film negatives -- they'll be transparent to the camera!) Combining images from two camerasSince infrared light is invisible to us, we have to use a different color -- red -- to represent it. More importantly, you need to take matching photos with a second, unmodified camera, and exactly align the visible and infrared photos -- "compositing" them with Photoshop, GIMP, or automated scripts currently in development (see links below).
Interpretation...soon Contributors welcome!Our work is far from complete -- many steps are difficult or time consuming, and we need your help to:
To learn more and get involved, see: http://publiclaboratory.org/tool/near-infrared-camera (a page which needs revision) http://publiclaboratory.org/wiki/dual-camera-kit-guide (a newer page which could be merged with the above) Older, longer outlineSix small features organized around a central large graphic (see above sketch) on an approx 11x17 area. 1. Science background
2. A second camera to capture NIR
3. Triggering the cameras in flight
4. Matching and compositing images
Advanced: To produce more precise results (link to web page):
5. Interpretation
6. Conclusion
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| 3 | warren |
June 18, 2012 19:04
| almost 12 years ago
Jeff W/Chris F are working on this feature for the upcoming Grassroots Mapping Forum. Sourcing a lot from: http://publiclaboratory.org/wiki/dual-camera-kit-guide, images from: http://publiclaboratory.org/notes/warren/5-17-2012/infrared-camera-how-guide-gm-forum Six small features organized around a central large graphic (see above sketch) on an approx 11x17 area. 1. Science background
2. A second camera to capture NIR
3. Triggering the cameras in flight
4. Matching and compositing images
Advanced: To produce more precise results (link to web page):
5. Interpretation
6. Conclusion
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Revert | |
| 2 | warren |
June 18, 2012 19:02
| almost 12 years ago
Jeff W/Chris F are working on this feature for the upcoming Grassroots Mapping Forum. Sourcing a lot from: http://publiclaboratory.org/wiki/dual-camera-kit-guide Six small features organized around a central large graphic (see above sketch) on an approx 11x17 area. 1. Science background
2. A second camera to capture NIR
3. Triggering the cameras in flight
4. Matching and compositing images
Advanced: To produce more precise results (link to web page):
5. Interpretation
6. Conclusion
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Revert | |
| 1 | warren |
June 18, 2012 19:00
| almost 12 years ago
Jeff W/Chris F working on this feature for the upcoming Grassroots Mapping Forum: 1. Science background
2. A second camera to capture NIR
3. Triggering the cameras in flight
4. Matching and compositing images
Advanced: To produce more precise results (link to web page):
5. Interpretation
6. Conclusion
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Revert | |
| 0 | warren |
June 18, 2012 18:51
| almost 12 years ago
Jeff W/Chris F working on this feature for the upcoming Grassroots Mapping Forum: 1. Science background
2. A second camera to capture NIR
3. Triggering the cameras in flight
4. To capture general patterns
Advanced: To produce more precise results (link to web page):
5. Interpretation
6. Conclusion
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Revert |
