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Information about this web site => Request for physics Simulations => Topic started by: wallenx on March 10, 2008, 09:09:33 pm



Title: Modifying a Java Applet
Post by: wallenx on March 10, 2008, 09:09:33 pm
Hi, Could you please modify the ray tracing java applet on this web site
http://mrl.nyu.edu/~perlin/experiments/autostereo/

so that it can track 5 simultaneous heads at the same time when in CYCLE mode [top right corner on page click]

The Original Java code is also provided on the site at the the following links:

http://mrl.nyu.edu/~perlin/experiments/autostereo/AutoshutterApplet.java

http://mrl.nyu.edu/~perlin/experiments/autostereo/GenericApplet.java

Thanks




Title: Re: Modifying a Java Applet
Post by: Fu-Kwun Hwang on March 12, 2008, 10:05:52 am
The following message was quoted from http://mrl.nyu.edu/projects/autostereo/
Quote
In order to present a stereo 3D image, each eye must see a different perspective rendered on the display corresponding to its position in space. The computer must know the position of each eye to accurately render the correct views. A parallax barrier 2-4" in front of the screen separates the views so that each alternating stripe is seen by a different eye. Note that the system can account for changes in the viewers position and orientation by changing its pitch. The barrier is dynamic - moving quickly over three phases so that it won't be perceived by the viewer. It rapidly cycles through 3 different positions (phases)  - at the end of the cycle each eye has seen every pixel on the screen, but different pixels at each phase. The use of 3 phases also allows us to separate the stripes by black spaces which allows for some registration errors in the system.
What I did not understand is that why some of the pattern are overlapping each other while cycles through 3 different phases.
I want to understand it (before I create one). Is there any movie should the real device and what it look like when it is in operation?


Title: Re: Modifying a Java Applet
Post by: wallenx on March 12, 2008, 08:37:38 pm
Thanks for the quick response. That's very kind of you.

The eye is an integrator so the barrier stripe (black lines) spends more time on the areas it's supposed to block and less time on the areas that the eyes are supposed to see through. Thus sometimes in the fast transitions from one position to the next the lines overlap but only briefly. And if this overlap is done at a rate that is faster than 60Hz the eye cannot perceive it distinctly due to the fact that human eyes cannot distinguish individual frames easily when the frame rate is 60Hz or above.

For example, if the display shows a 3D image to 1 person. Then it needs the separate the left eye image pixels from the right eye image pixels at a rate such that 60 Hz (full motion frame rate)  it shows the Left eye pixels while blocking the right eye pixels and also 60 hz showing the right eye pixels while blocking the left eye pixels. Thus the barrier has to move at rate r such that  approximately 120Hz <= r  to accomplish this.


For 2 viewers then it similarly has to cycle through all the four eyes of the 2 simultaneous viewers as well at a rate  r such that approximately 240hz <=r

For 3 viewers , then r is approximately 360Hz <= r
.
.
.
.
For n viewers , then r is  120Hz*n <=r

The advantage is that by cycling through the different positions instead of just being fixed at those positions the display brightness is increased.


Unfortunately nobody has ever actually build a display like this for more than one person [but the computations have been proposed] that I can show you.
 
Please see the following paper under the Controller Algorithm section and proceeding sections:

 http://www.evl.uic.edu/aej/papers/vr07.pdf 


Special Request: Actually if you could write the java simulation for just an arbitrary "n" number of simultaneous viewers that can be changed by the simulation observer that would be the ultimate goal as my barrier that I fabricated is actually capable of more than 25 000 Hz or about 208 simultaneous 3D viewers.

Again, thank you very much.


Title: Re: Modifying a Java Applet
Post by: Fu-Kwun Hwang on March 21, 2008, 08:03:29 pm
Sorry for the late reply. I was very busy during the last week. So I did not access this web site until tonight and I just found your message. I will try to read your pdf file during the weekend and response as soon as possible.
Are you in Taiwan right now? Because I just noticed that your IP is from NCTU.


Title: Re: Modifying a Java Applet
Post by: wallenx on March 24, 2008, 05:47:17 pm
Hi,
Thank you for the response. Yes I am in Taiwan right now. I am a foreign exchange student at NCTU working on a 3D Display project for multiple simultaneous viewers without the need to wear glasses.

Again, thank you for the kind assistance. Looking forward to hearing from you, and maybe one day I can stop by your University and thank you in person.