[Paraview] VRPlugin (some feedback)

[Nikhil Shetty]

Hi Stephan,

On Wed, Feb 8, 2012 at 7:38 AM, Stephan Rogge
<Stephan.Rogge at tu-cottbus.de>wrote:

> Hello,
>
> I’ve start to work intensively with the VRPlugin from git-master and want
> to get some feedback. First of all it works almost great :-). As a tracking
> system I’m using A.R.TrackPack2 with two infrared cameras and their VRPN
> server implementation.
>
> Awesome.


> To be able to compile that Plugin some modifications were necessary:
> *  As mentioned in this post (
> http://www.paraview.org/pipermail/paraview/2012-February/023816.html) the
> proxy API undergone some changes. But it seems, that the author of this
> post mixed up the parameter order.  He referred to proxy name and proxy
> group. But it has to be swapped...
>

The fix for this is available in the latest master. An update should fix
these. Also there is an updated documentation at
http://www.itk.org/Wiki/ParaView/Users_Guide/CAVE_Display

* Not important to me but required  to compile without errors:  In
> vtkVRUIPipe.h the flag QTSOCK is checked for existence. I had to put it in
> manually ("#define QTSOCK 1"). Don't know why.
>

With the new changes VRPN is default for windows and VRUI is default for
mac and linux. However you need to explicitly turn on VRPN
(PARAVIEW_USE_VRPN) if you want to use it on mac/linux.

If any time you want to use the VRUI device daemon make sure you #define
QTSOCK to 0 cause QT sockets are experimental and VRUI uses posix socket
calls (the reason its turned off on Windows). This will soon be changed to
use vtkSocket class which make VRUI cross platform as well.


> Further modifications was necessary in the the vtkVRStyleTracking in order
> to update the HeadPose. The proxygroup name must be changed to "views". The
> group name "interactorstyles" in the post mentioned above is NOT working,
> otherwise the plugin crash, since no proxy or property can be found and the
> pointer are still NULL after configuration.
>
> What you did is hardcoded to the view. The tracking style can be used for
tracking other things like the hand etc. This is configurable from the
state file (see document).

But so far, I was able to use the VRPlugin in ParaView in a two-side VE and
> I've got the feeling, that virtual object placed in front of the screens...
> :-)
>
>
Sounds good so far.

Now, I have a kind of problem. When I am moving parallel (left to right) to
> the screens, I can observe a sort of rotation which can be not described as
> moving parallax. It seems, that the rotation point lies in the center of my
> projection displays. Object which came out of screen "standing" not on the
> same position. They are flying around. So, my question is addressed to
> experienced Virtual Reality user: Is this described behavior right or not?
>
>  So some basic assumptions that we make is that the display configuration
and the tracker is in meters. That also means that the units for what is
displayed is also meters and is confined to the same coordinates as your
displays and tracking. If the configurations are not right then you
sometimes experience large movement of data as you move your head.

So if the object is between you and the display then when you move left the
object should move on the right side and vice versa (same for up and down).
 If you move too close then the object moves behind your head. So typically
objects are moving around wrt your head in a VE. However it is difficult to
say if it is the right behavior or not unless I can see what is going on.
It will be nice if you can produce some video ;).

-nix

Cheers,
> Stephan
>
>
>
>
>
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