Public Lab Research note


Super Redstone

by cfastie | | 3,459 views | 3 comments |

Read more: publiclab.org/n/10523


I took a new super-red Infragram camera for a test flight yesterday over a field that was scarred by logging activity last fall. ATV trails (four-wheelers) have been persistent in the field for years, but some of the new skidder trails are heavily disturbed and more prone to erosion. The landowner has planted conservation mix (grass and clover) on some of the new and old trails, so maybe we can watch the scars heal.
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The camera flown was a Canon PowerShot A590 with its internal IR block filter replaced with a piece of Wratten 25A gel filter. This red filtered Infragram records a very pure NIR signal in the blue channel and a mixed red and NIR signal in the red channel. The A590 is a high-end 8 MP model from 2008 with some features rarely found on the PowerShots typically flown by Public Lab folks. It has a built-in mode for shutter priority, so I locked shutter speed to 1/640 second (it was cloudy). It has true manual focus, so I locked focus on infinity. It has a removable ring around the lens that exposes a bracket for mounting a filter tube. I put that in place just for added lens protection. CHDK was triggering the shutter every 6.5 seconds.
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I flew the A590 on a Redstone Rig that had the tray modified to fit this camera snugly. This keeps the camera secure and balanced regardless of tilt angle, but I locked the tray with the lens pointed straight down. A Picavet suspended the rig from the kite line, and all the photos seem to be nicely vertical and sharp. The rig was lofted by a nine foot Levitation Delta kite with winds around 10 mph. More than 200 photos were taken during the 20 minute flight.
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I manually stitched 17 of the photos in PhotoShop using a screen capture from Google Earth as the background. I exported the final jpeg (a 35 megapixel image) and used Fiji to make separate images of the red and blue channels and an NDVI image. I used PhotoShop to make the false color IR image. The new and old trails are well documented in the images, and the wet and dry places in the field are also distinguished. The sandy soil of this old glacial delta dries out fast and plants grow better in swales and low areas where there is a little more soil moisture.
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Embedded gigapans no longer display here, but you can see it here: http://www.gigapan.com/gigapans/155962/

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I am going to sell this entire camera rig, including the camera. The customized Redstone Rig, Picavet, and IR modified super-red Canon A590 can be ordered at the KAPtery for $178. There is only one of these, the one in these photos. It is fully assembled and ready to start shooting. Batteries not included.


3 Comments

cool


Those are rock bottom prices for a converted camera and rig. Nice to see the KAPtery really delivering.


Great value. Very nice results. Seems retro (perhaps a barnstar is in order). Very nice, rich feature set, now repurposed, "recontextualized," into this role. Looks like it is still available at the store. Won't be for long. Thanks for all the work you do for us!


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