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May 31, 2004, 06:48 PM
StereoAerial Photographer
jlballou's Avatar
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New Platform for Stereophotography: CN2X


Here's the latest platform that I've been working on for a couple of months: The CN2X! (Its name is sort of a rebus - you'll figure it out. It sports two Aiptek 1.3M SD cameras, looking to the right of the fuselage. They are operated using Wild Moose's Backpack switch.

Motor: Mega Motor 16/15/7 direct driving a MA 9x6 electric prop.
Speed Control: Phoenix 10
Batteries: 8x1000 mAh NiMH
Wing: 68" span scratch built - same wing as the LocalHawk Lite
Fuselage: Two different size econo towel bars joined by lite-ply shims
Tail Feathers: Coroplast
AUW: about 41 oz.

Notes: This plane is definitely not overpowered. Still, it climbs steadily, has a motor-on time of about 6 minutes, and has a very smooth glide. Pictures taken with the motor on are not wavy, though that may change if I decide to upgrade the power. The platform has been in flight testing for a week before mounting the cameras. I just integrated all of this stuff this morning, and flew this afternoon.

Camera mounts will be improved (filament tape doesn't provide accurate location, and the foam wedges don't control camera angle well either).

This platform will allow stereophotography of moving objects and up-close subjects. I am also looking forward to using the camera pairs to do non-aerial stereophotography.

John
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May 31, 2004, 07:48 PM
Tell that to George Zipp!
mikeb33's Avatar
That looks cool. Now just try going quadraphonic!
That esc and those batteries could use an upgrade. Try a 3S lipo like a TP2100 and a CC25 esc with the same prop and you will climb!

MIKE
Jun 02, 2004, 01:13 AM
Registered User
rtideas's Avatar
too cool! post those shots. my eyes need the exercise.
Jun 02, 2004, 01:50 AM
StereoAerial Photographer
jlballou's Avatar
Thread OP
Mike, I'm trying to save some money to get an upgrade to the propulsion system. I'm not sure that I'm ready to try the LiPo route yet, though. Actually, this platform is not designed to get up high - I have two other platforms that do that quite nicely, and this one is mainly for low altitude shots of close subjects. However, I know that it will thermal well, and if I can get in a hatsucker with some hawks or vultures, I may be able to get some stereo shots of the birds, which would be wonderful!

rt- I worked tonight on a better camera mount, and I think what I came up with may allow better alignment. There are two stereo shots posted to the gallery, at the following addresses:

http://rcgroups.com/gallery/showphoto.php?photo=8323

http://rcgroups.com/gallery/showphoto.php?photo=8329

The first one is for the current contest, and the second is a higher shot of the site I took the first one.

I'm attaching another one from the same flight also, of the local middle school. This one is not the best - It shows that the color balance is different in the two cameras, and the focus on one is not quite right. I re-adjusted the focus this morning, and I'll work on improving the post-processing to get the colors to match more closely.
Last edited by jlballou; Jun 02, 2004 at 01:54 AM.
Jun 02, 2004, 01:59 AM
Registered User
rtideas's Avatar
A slight upgrade may be an APC prop. I switched a GWS prop to my APC prop and dropped in amps and upped the thrust and speed noticeably (but I was using twin brushless motors).
Jun 02, 2004, 11:20 PM
StereoAerial Photographer
jlballou's Avatar
Thread OP
Thanks for the suggestion, rt - I'll pick up a couple the next time I'm in the LHS.

Well, I was unable to get away to fly today. Lunchtime was taken up with other things... But, I had to check the alignment of the two cameras with the mounts I made last night. So, this evening, I stood out on the back deck, held up the fuselage, and took some shots. I picked the most "Aerial-Like" pair of photos, and put them together into a stereo pair.

Even though the camera cases look completely parallel, the images are about 3 degrees off - No problem, rotating them those 3 degrees placed them in complete alignment. I'm getting better at matching the color differences, as you can see from this pair.

These are NOT aerial photos, so don't think this was the last shot before the trees snagged the whole plane.

Maybe tomorrow will allow a sortie...
John
Jun 03, 2004, 06:05 AM
John:

Looks good. I have been trying to decipher CN2X.

I get "Seeing Two Times". I guess that could be "Seeing Twice".

David
Jun 03, 2004, 09:19 AM
StereoAerial Photographer
jlballou's Avatar
Thread OP
David - Close! Actually, it's "Seeing Double", since it mounts two cameras.
John
Last edited by jlballou; Jun 03, 2004 at 10:20 PM.
Jun 03, 2004, 10:23 PM
StereoAerial Photographer
jlballou's Avatar
Thread OP
I was able to fly today at lunchtime, and here's one of the pairs that shows the advantage of the two cameras: The cars on the freeway are in the same place in both photos! With the old system, they looked pretty funny. This is part of the construction of the new Benicia/Concord bridge.
Jun 04, 2004, 11:22 PM
The more I look at these the more I hear my mom saying "Don't cross your eyes. They're going to stick like that!"

Is there some kind of formula as to how far the cameras should be apart from each other for a given distance from the subject? Looks like you have them pretty far apart. 2 1/2 feet maybe? I have got to get me a big bird and try this.
Jun 05, 2004, 01:21 AM
StereoAerial Photographer
jlballou's Avatar
Thread OP

Power Upgrade


Hello, Monkey - The lenses ended up being 19.5 inches apart. I just figured on how far I could go in front of the CG and behind to make the CG stay the same if I took the cameras off. There is a rule of thumb for stereo photography, and I think it's about a 30:1 ratio minimum. This is the ratio of the distance to the subject to the distance between the lenses. If you go smaller, say, 10:1, it is difficult for your brain to fuse the images and make sense of them. It's a good way to get a headache, besides. For more information about stereoscopy, visit:

http://www.stereoscopy.com

All of my earlier stereo efforts were done with one camera, and the spacing between the exposures varied from around 10 feet to as much as 80 feet or so. That meant that I had to be a long distance from the subject. This technique is good for distant landscapes, mountains, lakes, bays, etc, but the main drawback is that if anything moves between exposures, it shows up like a sore thumb in the stereo pair. That's one reason why I wanted to mount two cameras in one ship. The other reason is that I want to take closer shots of things. I haven't yet flown a sortie to try to get such photos yet, but it will be coming soon.

I upgraded the propulsion system. I added quite a bit of weight, but the added power gives it truly vertical performance. I took the motor/sc/batteries out of the LocalHawk IIL and strapped them on to the CN2X. New AUW is 61 oz, which is about 30 ounces less than the LocalHawk IIL.

Motor: Jeti Phasor 30/3
Controller: Castle Creations 60A (don't really remember)
Batteries: 8X3000 mAh NiMHs
Prop: (initially) MA Electric Only 11X7

I will probably play around with different props to see what will give me the best thrust/current draw tradeoff. As it is, I flew the first sortie with it this afternoon, and used less than 1/3 capacity to get to at least 800' AGL. I did get some shots, and I'm attaching one stereo here to show the altitude results.
Jun 05, 2004, 04:48 PM
StereoAerial Photographer
jlballou's Avatar
Thread OP

Wavy Terrain ;)


Well, I tried out taking photos with the motor on low speed, and I'm sure you guessed the outcome. There are waves in the pictures!

Check out this photo - It really doesn't look too wavy until you check the stereo effect. It really looks like a "rolling hill".

John
Jun 09, 2004, 09:38 PM
StereoAerial Photographer
jlballou's Avatar
Thread OP

Update on Upgrade


Here's a short description of the changes that I've made that has improved the performance and increased the capabilities of the CN2X. The first picture below shows the right front side of the fuselage, with the Jeti 30/3 BL motor and Castle Creations Phoenix-60 controller. The new camera mounts improve stability and alignment, yet maintain good vibration isolation. The landing gear now has rubber-band springs to provide better cushioning on landings, and better ground handling. They are held in place with wheel collars that are large enough to fit over the bends in the piano wire.

The second picture shows the backside of the camera mounts. I used a heat gun with the rain gutter material that I use so much of (all my planes have at least a small part made from it!) to thermoform an angled bracket that combines with double-stick foam tape to hold the camera in position. After the alignment is close, I use the strapping tape to lock it on to a more or less parallel position. With this alignment aid, the stereo pairs match up almost perfectly, with only small adjustments required in post-processing. The SMT BackPack switch which controls both cameras can be seen at the top. Also, you can see the small foam wedges between the fuselage and the camera that assist in holding the camera for alignment and providing some shock dampening.
Jun 09, 2004, 09:48 PM
StereoAerial Photographer
jlballou's Avatar
Thread OP

Sample of "Unprocessed" Stereo Pair


I'm attaching a stereo pair taken from the Golden Gate Fields parking lot in Albany. These photos were only resized after placing them in the same file. As you can see, the color balance is slightly different, and the horizontal placement is a little off. However, nearly all of the photo is available for stereo viewing, which is the main reason for this platform. I'm also experimenting with close objects, and it seems that less than 200 feet or so does not yield good stereo results.

BTW, the peninsula sticking out in the photos is where Lacy Peterson and her unborn son's bodies were found.
Jun 09, 2004, 10:20 PM
Old Timer
California Condor's Avatar
If you would reduce the width it will be much easier for us to view.


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