Hi,
during the last few weeks I tried to use Java3D to create stereo vision
3D applications on various platforms. This posting summarizes my experiences
and
I hope they are useful to others.
Ciao,
Carsten
Setting 1:
* Intel Pentium,
* Asus V8200 (Geforce 3 T5)
* Windows 2000,
* JDK 1.4.0,
* Java 3D 1.2_04 to 1.3 beta 2
Results:
- When using the original Asus drivers I did not get any stereo.
Even the stereo demos which came with the card crashed windows 2000.
- So I installed the drivers from the Nvidia web site:
* No stereo in OpenGL
* Success however with Direct X in fullscreen mode. In this setting the
graphic
card driver automatically converts D3D into stereo images (Be sure to
activate
the appropriate mode in the driver control panel). This works with all
D3D applications and the stereo-preferred switch in Java3D is
irrelevant.
Some problems however:
1.) Java 3D 1.2.x is very very very slow in stereo mode. (which is odd since
Java3D
technically is not in stereo mode. But it is much slower than when switching
stereo off).
Good performance with Java3D 1.3 though.
2.) The images for the left eye and the right eye are too far apart by
default. Much too far apart.
This can be compensated in the driver control panel, but only by setting the
separation
values to minimum (while still having stereo) there. This is unfortunate as
it does not allow
for any fine-tuning. The other D3D programs I tried did not show this
behaviour.
3.) Mouse events are only forwarded to the Java3D application if the mouse
action started
in the area where the window originally was on the desktop before switching
into fullscreen mode.
4.) In about 70% to 90% (I'm guessing here) of application starts the stereo
mode does not work correctly. It seems the
first program start after a re-boot has much higher chances to work ok. The
following
pathological behaviour can be observed:
* The image for one eye is not drawn correctly at places where objects are
drawn for the other eye. This looks like
a z-buffer problem. This is the most common problem.
* When the displayed image changes (camera motion, changes in the scene)
about every second or third (I'm
guessing here) frame for one eye shows the original desktop instead of the
Java3D scene for that eye. This hardly
ever happens on the first application start after a reboot and almost always
happens on any subsequent start.
* The stereo image is inverted. Objects which should be close to me are far
away and vice versa. The visual effect
is that images which my brain thinks are close (because of the stereo
effect) are smaller than objects which
should be further away. This also screws up the z-buffering. To clarify:
Looking at the image in "2D" it would
look ok, just the stereo driver puts thew wrong things in front. This
problem occurs rather rarely but every now
and again.
All these things sound like driver problems. However, Java3D is the only D3D
application, I tried so far, which shows any
of this pathological behaviour. Even when one of these other programs is
started after Java3D did not work correctly, they
still don't show any of this behaviour.
Setting 2:
* SGI Onyx2, Irix 6.5,
* Java 1.3.1, Java3D 1.2.1
Works when using the shared Z buffer switch for Java3D (make sure your
X-server is in a stereo mode!). The eye separation, again, is much too high.
Apparently this can be
fixed by using the Java3D view model, but I could not verify this so far.
It's quite slow.
Setting 3:
* SGI O2, Irix 6.5
* Java 1.3.1, Java3D 1.2.1
The image for one eye is drawn incorrectly. Areas where parts of the image
for the other eye are
drawn are sometimes not drawn. This looks like a z-buffer problem. The
shared z buffer
switch which worked fine for the Onyx2 does not have any effect on the O2.
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