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Submitted by Andy Maddison, posted on April 27, 2001

Image Description, by Andy Maddison

Here are 4 screenshots grabbed from a video (avi) I made for my final year project when I was at university. The project's subject area was Augmented Reality, which is the composition of computer generated graphics with real images at interactive frame rates. The project involved moving a computer generated object (cube) around a real scene (lego arch on a piece of board) in real time. The cube was moved around the scene using a mouse and collision detection was implemented so the virtual object would 'collide' with the real object. The screenshots show inter-object shadowing between the scene and the cube, and occlusion of the cube by the scene.

The original idea was to have a virtual ball rolling around the scene, but the hardware I had to work with (combined with my inefficient code) was not up to the task.


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Archive Notice: This thread is old and no longer active. It is here for reference purposes. This thread was created on an older version of the flipcode forums, before the site closed in 2005. Please keep that in mind as you view this thread, as many of the topics and opinions may be outdated.
Igor Kravtchenko

April 28, 2001, 02:52 PM

Excellent !
It works like " video compositing " .

Andy Maddison

April 28, 2001, 03:07 PM

Greg, see my post above.

I was sooooo into the technical lego (remember the car with independent suspension?) when I was young (early 80s). In fact we had a school open day and I was told to sit at a desk and just make things for a couple of hours as people looked around :-)



April 28, 2001, 05:05 PM

A have to apologize for my remarks, I was as drunk then as i am now, I hope you bear with me :) Damn, that cognac does the job.


April 28, 2001, 05:08 PM

This IOTD is really cool the shadows match pretty good and it looks really great. I love lego, I remember building cars with imaginary laser cannons and giving them far out names. Looks great, I apologize.


April 28, 2001, 05:57 PM

Did you get one of those lego driving licensens?

p.s. i'm from denamrk :)


April 28, 2001, 06:50 PM

OK, I understand how you've done this. Simple, but you've done it quite well nonetheless.

Fellow flipcoders:
It's essentially an entirely computer generated image from 3D models, except that for every pixel that is not part of the cube object, that pixel has been taken from a REAL photo. Think about it for a bit if you don't quite get it first off.
And of course he's added shadowing too which slightly darkens the image where the shadows pixels are. Great idea but you may notice that the shadows colors vary slightly between the artiicial and real ones.

Well integrated dude!


April 28, 2001, 06:55 PM

Depends what country are you from?
don't forget that most of the coders in America are not americans...
and also there is more coders outside america, and not all know about LEGO - or dutchs? is LEGO ducth?

But i've played lego, really - we were having LEGO at kindergartens - and I was able to play it there - it was epxensive though my mom/dad to buy me one. Like kids we were playing mostly by beating one each other with stones and other stuff... it was like Drakan a little bit, quake was not born...


April 28, 2001, 06:57 PM

But seems not so expensible to me (or maybe is it?)

Next generation of INDIE HORROR/SCI films can use such visualizations!!


April 28, 2001, 07:12 PM

I am... a little confused. If you take the model from a meticulously recreated 3dmax model, and do all the intersections and shadowing with that, what is it that's so complicated about the whole thing in general? Isn't it a matter of doing the math for intersections and shadows, rendering the scene for depth then turning off rendering to the depth buffer and putting the video (or still?) image over the top, then rendering the cube, after which you multiplicatively render the shadows you need on top? The only way the real life bit seems to come into it is as a texture you lay over the top and objects that you should render into the depth buffer beforehand rather than after.

Maybe I'm wrong, I'm just a little puzzled at the moment.

Vander Nunes

April 28, 2001, 07:59 PM

Yes, I know Augmented != Vision, this is exactly what I was trying to say. Some people was thinking the IOTD was about Vision, so in other words, I said "I don't think it has any type of Computer Vision"...


April 28, 2001, 08:38 PM

"Like kids we were playing mostly by beating one each other with stones and other stuff"




April 28, 2001, 09:06 PM

Hey man, if you just took the picture then rendered it in max ,does that mean you cheated on your university project? lol, very creative project! Too bad we can't see it though :( .


April 28, 2001, 09:20 PM

What? dutch? no, it's danish.

I remember playing with lego with my friends, I was always crap at building anything than what was descriped on the boxes... my friends on the other hand... big detailed spaceships and such.

Gee, that was depressing. Not to mention that you had to be a certain age to ride the cars in Legoland. Now that I think about it, I hate lego, I wanna go down to basement and set my big box of lego on fire!...

Which reminds me of how we started to put our toy cars on fire with gasoline and smash them with hammers and stuff, anyone else been doing that?

Anyway, interresting picture, would have liked to seen it with a ball, moving... would have made a nice screensaver I think.
And lego's alright I guess, there's just never enough of the blue ones, or was it yellow, or black....


April 28, 2001, 11:33 PM

Check out for some cool applications of augmented reality

Kevin Kennedy

April 28, 2001, 11:48 PM


Hey, I came in last place when I did the lego robot competition my third year at MIT. Oh well, at least I stayed drunk most of the time. Here's my little lego project I know I try to make it sound waaayyy beter than the thing really is.

Kevin Kennedy

April 28, 2001, 11:49 PM

Sorry, I did not specify, this is not the robot submission. Something else I did when I should have been doing my real job.


April 29, 2001, 12:26 AM

That was so incredibly insightful and well-reasoned. Good show.

And people wonder why I never post to Flipcode anymore.

Mark Friedenbach

April 29, 2001, 01:21 AM

Which reminds me of how we started to put our toy cars on fire with gasoline and smash them with hammers and stuff, anyone else been doing that?

Uh... I think you need some therapy. ;)


April 29, 2001, 05:54 AM

OK - finally remembered what I actually meant to post in my previous post. Something my Cybernetics department is playing with is augmented reality via VR goggles. The goggles are transparent, and a basic 3D model of the department is overlaid on them, so if you're looking at a door, you're seeing the real door & an overlaid wireframe one.

Now, the entire deparment (well, most of it) is hooked up with Neuron PICs. Doors, lights, computers, sensors - if you can attach a PIC to it, they've got it connected. So, while wandering around with these goggles on, you can, say, look at a door, press a handheld thumb button, and the door opens! Or look at a light, press the button, the light comes on! Its the ultimate device for lazy people....
Quite cool too, though.

Incidentally, nice IOTD. It's always good to see something different for a change, even if it isn't quite as complex as I first thought. (Don't get me wrong - it's still quite cool. I just would have been seriously impressed if you were inferring 3D data from that single image.)


Andrew Cox

April 29, 2001, 09:25 AM

Jo, alle menneske for dem vis de go por Lego billen.

Unskun for min Danske. Min hel famillen teller Engliske or derfor har Jeg har egger ouver det.


PS Jeg ere kun in halv dansk.


April 29, 2001, 05:23 PM

You don't know how right you are :)


April 29, 2001, 05:42 PM

Where did you read that most of the coders in America are not americans? Do you have any data to back up this ridiculous claim?


April 30, 2001, 02:34 AM

man får ikke kørekortet hvis man fræser ind i toget ! (o:


April 30, 2001, 04:12 AM

I love AR and VR but I always thought that AR stood for animated reality, makes little difference. The stuff that I have read on AR they usualy put coloured balls dotted around the scene and the computer uses a load of trig to get the cameras position. I think one guy was trying a new technology buy uses little transciever radio type things planted about the scene. Other cool thing are gloves that are like the normal VR gloves you can use to manipulate an object in the scene but that also have the objects shape recorded so you get physical feedback. I.e you pick up a steel ball but you wont be able to close your fingers further than the shape of the ball, but if you had a soft tennis ball you could squish it slightly. One cool use for AR is that basicly what you have is a hologram, except you have to where a helmet.


April 30, 2001, 11:31 AM

Actualyl I did that too ... cut off the ends of a whole load of matches cram them into the car and then set fire to it while filming. The explosions me and a friend had actually blew the doors off one of our cars :)


PS. Yes I AM a nut case :)


April 30, 2001, 12:37 PM

DP: You realize, of course, that there's only 676 two-letter acronyms possible in the English alphabet, right?

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