RoboRealm Forum

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Tue, 30 Nov 1999 00:11:00 EST

Hello STeven,

Thanks for your analysis and the .robo file. I polished the heck out of the 4" ball with both Basso and stainless steel polish but the surface just doesn't want to get much better. Ironically, and after all this, I went back to one of my Christmas ornaments, which is highly mirrored if somewhat small and misshapened, and it might just do the trick after all. I don't have the setup handy that I had yesterday to show you a comparative image right now. But for omni-directional motion detection, it could work fine. And an added benefit (for a mobile robot), is that the ornament weighs almost nothing.

--patrick

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Tue, 30 Nov 1999 00:11:00 EST

Naturally the 8" truck mirror looks the best. But here are the three images using the polar unwrap to get things into a more meaningful representation for us. Note that we cropped the upper and lower parts of the image as they don't add anything to the image.

Best and most undistorted.

A Little blurry but the image also seems to be skewed in some strange way. The can seems to vier off to the side!

Not a bad middle ground ... with some polishing it might work well.

Note that the mirrors are not perfectly round so the middle tends to bulge a little ... this can be fixed using the radial distortion module. the robofile we used to align the first image is included below.

Thanks patrick for posting these ... a fun exploration into 360 spherical cameras.

STeven.

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Tue, 30 Nov 1999 00:11:00 EST

OK, here are some panoramic images captured from three different spherical mirrors.  I put a few objects on the floor around the mirror including two colored balls and two boxes with large print on them to see if you could read the lettering.  The camera is a Logitech Quickcam 5000 sitting between about 5-12 inches away from the mirror depending on the size of the mirror (so as to fill the screen).   The black "strips" running from top to bottom of the images are the legs of the table from which I suspended the mirrors over the camera.

The first image is the best and is taken using an 8" truck mirror purchased at http://www.gpartsinc.com/sp-580.html.  The surface is highly polished and very clean.

The second image is taken using a 6" stainless steel garden gazing ball obtained from http://www.krupps.com/Gazing-Balls/_0_0_35_3_mol409990sil_3_3.  Note that the surface could use some polishing as it is a little cloudy but I don't currently have any polishing material:

The third image is taken using a 4" version of the garden gazing ball. Its surface could also use some good polishing:

Since my main objective is 360 degree motion detection, even the 4" ball might be good enough for that purpose.

In the meantime, I noticed that some more professional systems, like the one at http://www1.cs.columbia.edu/CAVE/projects/cat_cam_360/ use a much smaller reflective ball with the camera much closer--perhaps using a macro lens?  Also, here is a cool video using a DIY system using a camcorder:

http://videothing.blogspot.com/2005/05/my-ghetto-360-video-experiment.html

--patrick

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Tue, 30 Nov 1999 00:11:00 EST

Hi STeven and Thijs,

I received a pair of stainless steel "garden gazing balls" as shown here:

http://www.krupps.com/Gazing-Balls/_0_0_35_3_mol409990sil_3_3

The surface is reflective but could use some polishing before I upload some images. Stay tuned...

--patrick

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Tue, 30 Nov 1999 00:11:00 EST

Hi STeven,

Thanks again for the link to the ptgrey cameras. Unfortunately for me, their prices are beyond my current budget, but it does look like nice hardware. Since I had to request the prices by submitting a form, I won't post them here, but others can do the same through their web site.

--patrick

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Tue, 30 Nov 1999 00:11:00 EST

Thanks for the links! I was wondering if any of the mirrors in the ArboSci kit are curved enough to see horizontally when looking down from the top? For example, I picked up a 2.5" "spot mirror" that you can stick onto your car's side view mirror, but the convexity is too shallow to see horizontally when looking straight down at the mirror--or straight up for that matter if the mirror is held above pointing down.

--patrick

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Tue, 30 Nov 1999 00:11:00 EST

For absolutely exactly what you need you can go to edmunds optics.  (When I am not paying for it!)  They stock tens of thousands of different optical components:
www.edmundsoptics.com

For some small ~2 1/2" inch spherical mirrors you can order them from.
http://www.arborsci.com/
We bought a kit of 6 different mirrors for about $15.

Also surplus shed also has some nice mirros sometimes:
http://www.surplusshed.com/

If you really want to make exactly what you want, you can buy aluminized mylar film at most art stores.  You can then cut and form this into whatever you want.

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Tue, 30 Nov 1999 00:11:00 EST

Thanks STeven. I have submitted a request for a price quote on their website and will report back what I find. In the meantime, I purchased an 8" convex truck mirror off the web and it images very nicely through my webcam but I think it is really just too big for my robot. Will keep searching for something smaller.

--patrick

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Tue, 30 Nov 1999 00:11:00 EST

Not sure about price on this on but we just remembered this link for a spherical camera:

http://www.ptgrey.com/products/ladybug2/samples.asp

STeven.

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Tue, 30 Nov 1999 00:11:00 EST

Hi STeven and Thijs,

Thanks for the very useful information! What a great idea to use a Christmas ornament. I'm going to look into security dome mirrors--at least now I know what to look for.

Thanks again!
patrick

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Tue, 30 Nov 1999 00:11:00 EST

Hi Patrick,
http://www.overtoom.nl/panoramaspiegels-acryl_M196417.html

Don't buy the half one for 100,- but the full dome...

Thijs

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Tue, 30 Nov 1999 00:11:00 EST

Hi Patrick
I used a webcam and a Christmastree bal, together with polar-transform
and that worked, but with very low quality.
A round mirror is better and is used in shops for security and so.
A Dutch shop sells them for about 100 dollar:
http://www.overtoom.nl/panoramaspiegels-acryl_M196417.html
Notice that the view of the fisheye is 360 x 180 and that of the mirror
close to 360 x 360.
Succes!
Thijs

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Tue, 30 Nov 1999 00:11:00 EST

Patrick,

Yes, there was a servo article written a while back

http://www.servomagazine.com/preview.php?issue=42

and we've been talking with a Canadian soccer team using such a camera at

http://robofoot.polymtl.ca/

which lead to the development of the polar module discussion

http://www.roborealm.com/forum/index.php?forum_id=1732

whom you can try contacting from their website. (or post something in that thread and he'll probably still get an email).

STeven.

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Tue, 30 Nov 1999 00:11:00 EST

Thanks STeven. I've seen pictures of some home made systems that use a parabolic "half dome" mirror together with a webcam that is mounted above the mirror and pointed down toward the top. Do you know where such a mirror can be obtained?

Also, you said it is quite easy to create a parabolic or conic lens: can you point to a reference for doing this? (I've struck out on Google.) The best I've been able to do so far is to take apart a Logitech Quickcam Fusion webcam and glue a 150 degree wide-angle lens (normally used with a video surveillance camera) against the original lens holder (which I had to file down a tad to get the focal length right.) It's not 360 degree and the image quality is not that good...

Thanks!
patrick

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Tue, 30 Nov 1999 00:11:00 EST

pirobot,

Thanks for the link, we had looked around a couple months ago (but only casual browsing) and did not find anything but custom created cameras. As it is quite easy to create such a lens whether they be parabolic or conic it seems that most people are creating these types of optics themselves.

But keep looking and let us know what you find! We'll continue to keep an eye out too for such a camera (it is always nice to have a commercially available option).

STeven.

360-degree video hardware?

Tue, 30 Nov 1999 00:11:00 EST

Hello,

First of all, many thanks for making RoboRealm available.  This is an incredible piece of software and it has become an essential component of my autonomous robot project, as well as a terrific learning tool.

I am interested in acquiring a 360-degree video system for my robot to use with RoboRealm, but so far I have struck out finding anything commerically available.  The closest I have come is:

http://www.poc.com/emerging_products/omniview/default.asp

which is still in the prototype phase.

I was wondering if anyone out there has found a source for such a beast?

Thanks!
patrick