WorldViz User Forum View point question
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#1
11-29-2009, 08:00 PM
 atamasan Member Join Date: Jul 2009 Posts: 26
View point question

Hello.
I've wrtten some questions here so far and got good hints, thank you.

Now, I use HMD, and Polhemus MoCap system. Polhemus transmiter is a cube, so I made a same scaled cube in the 3D world and it is placed at (0,0,0) in world coordinate system (because the real one is at (0,0,0)) .

The HMD is "see-through". So when I use the HMD, I think I can see both the real transmitter and 3D cube. I want to see them like they are piled up through the HMD even if I move or rotate my head (they should be seen like they are at the same position and same size).

I thnik I should control camera, window, or view point or something to do that, so I've created and tried some methods for that. But I'm still confused.

I believe there're good methods for that.

#2
12-09-2009, 04:11 PM
 Jeff WorldViz Team Member Join Date: Aug 2008 Posts: 2,471
It the viewpoint and the cube model you have are in the same coordinate system and you place the cube at the origin then it should appear at the position of the transmitter. If you are applying any type of scaling or other transformations to your tracking data then this could cause problems. You will need to take into account the offset of the sensor from your eyes, if there is any, to get a perfect match of the cube and transmitter. Also if the tracking is off then getting a good match will be difficult.
#3
12-10-2009, 08:36 PM
 atamasan Member Join Date: Jul 2009 Posts: 26

Yes, the cube I made and the real transmitter are in the same coordinate system.
Oh I didn't have ideas about offset.
The size of the real transmitter is 10*10*10[centimeters]. So I defined the cube like this. cube=viz.add('box.wrl') cube.setScale([.1,.1,.1]) In this case, the size of my cube is 10*10*10[centimeters]??

By the way, a polhemus sensor is linked to my HMD, but it's not placed at display monitor of the HMD. It's placed at my forehead now. And then, datas from the sensor is linked to "viz.MainView".
I noticed that the sensor is oblique angle against the HMD, so I think this could cause problems. Because when I look at the front, "viz.MainView" don't look at the front.

Last edited by atamasan; 12-10-2009 at 08:41 PM.
#4
01-11-2010, 05:59 PM
 atamasan Member Join Date: Jul 2009 Posts: 26
I am sorry, I've got a another question.
To solve the problem I wrote above, should I change the frustum?

I think I don't have to do, but I wnat to know the truth.

#5
01-13-2010, 01:49 PM
 Jeff WorldViz Team Member Join Date: Aug 2008 Posts: 2,471
To get the virtual cube and transmitter to match you do not need to change the view frustum.
#6
01-13-2010, 07:21 PM
 atamasan Member Join Date: Jul 2009 Posts: 26
O.K, I will not change the view frustum.

When I wear the "see-through HMD", at first I close my left eye and use only my right eye. Then the real transmitter and the virtual cube are about 90% match, but when I close my right eye, they are not match. I don't know what is the difference between
right eye and left eye.

Anyway, thank you again.
#7
01-26-2010, 01:19 PM
 Jeff WorldViz Team Member Join Date: Aug 2008 Posts: 2,471
Sorry, I think I made a mistake here because changing the frustum will alter the field-of-view . You'll want to make sure that you set the fov in Vizard to match that of your hmd.
#8
01-26-2010, 05:56 PM
 atamasan Member Join Date: Jul 2009 Posts: 26
Hi, thank you for the reply.

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