Public Lab Research note


Titan 2 IR flight

by cfastie | August 08, 2014 04:52 | 94 views | 2 comments | #11021 | 94 views | 2 comments | #11021 08 Aug 04:52

Read more: publiclab.org/n/11021


I took a new Titan 2 IR rig for a test flight yesterday. I flew the Fled kite over a clearing where in May I had documented skidder trails from a logging operation. On the ground these scars seemed to be recovering well especially where the roots of damaged perennial plants survived to send up new shoots. Older trails used for many years by ATVs have also started to heal since motorized travel was prohibited in May. No roots survived on these bare trails, but annual grasses are filling in even where no seed was sown.
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Mosaics from about 8 photo pairs from the Titan 2 IR rig. Annual grasses are growing in the bare ATV trails (bright green vertical strip at left of RGB image). Growth from perennial roots is healing the skidder trail (gently sinuous vertical stripe near center of images). A wet summer has allowed good growth, but sandy, well drained soil in this clearing limits productivity compared to the surrounding forest. False color infrared (NGR) and normalized difference vegetation index (NDVI) images are made from pairs of RGB and NIR photos. The NDVI image uses a newly devised color table.
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The cameras on this dual rig are new Canon PowerShot A1200s. One camera had its IR block filter replaced with a small piece of Wratten 87 polyester filter so it captures pure near infrared light. Photos from this camera are interesting in their own right and highlight the brilliant reflectance of near infrared light from vegetation.
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Photo taken by the IR converted Canon A1200 that flew as part of the Titan 2 IR rig.
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One of the photos taken by the IR converted Canon A1200 on the kite flight. The ATV and skidder trails are evident.
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This Titan 2 IR rig with all cameras and electronics is for sale at the KAPtery for $299. The 3D printed rig is customized and assembled and includes a Picavet suspension. The new A1200 cameras are probably Canon's most lightweight model that uses AA batteries. Each camera has a 4 GB SD card with CHDK installed and configured for remote synchronous control by an external timer. CHDK is also configured for shutter priority mode to lock shutter speed while aperture is adjusted to expose each photo properly. A modified MK111 timer in a custom 3D printed housing has a USB Y cable to send triggering signals to the cameras. A switched battery case for four alkaline AAAs can supply power for several hours to trigger the cameras every five seconds. Batteries not included. [Update VIII/10/2014: this one sold, but I have ordered supplies to assemble another one]
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2 Comments

Chris, Nice rig. Great value. I like the results. Has there been discussion of the Wratten 87 polyester filter vs Wratten 25?

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Hi Pat,
The Wratten 87 passes only NIR; it's great for the NIR camera in a dual camera rig. The Wratten 25 is the best filter I have used for a single camera NDVI system. It could also be used in a dual camera rig because the blue channel would be mostly NIR, but it might also include some UV and a little red. I think the photos from a Wratten 87 camera are a little crisper than the blue channel from a Wratten 25 camera. But I have not done a careful comparison.

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