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kevin 06-24-2011 02:49 PM

nVis SX/111 Display
Hi all,

The lab I work in has run into a problem with the display of the nVis SX/111 visor. The framerate seems to be rather low, or perhaps some frames are skipped. When turning the head (tracking being done by Intersense) there is significant jitter in the image as it updates at a rate that I would estimate to be around 20 hz. This problem is only present in the HMD itself. Monitors set up to also display left and right eye images are running smoothly.

I briefly tried using the nvis.nvisorSX() command instead of nvisorSX111(), and despite the display being rather distorted, it ran much smoother in the visor. Any suggestions as to what might be causing the problem?

farshizzo 06-28-2011 08:44 AM

It's difficult to tell what is going on without more information. There might be a high-poly object in your environment that is causing the framerate to drop when it comes into view. The only difference between the nvisorSX and nvisorSX111 commands is the field of view that is applied to the window. the nvisorSX111 has a larger FOV, so that means more objects are visible. If you bring up the onscreen frame stats, how many polygons/drawables does it report?

kevin 06-28-2011 09:24 AM

I was wrong about the SX setup function showing better results; running it again caused the same problem as the SX/111. There are no high poly objects in the scene; only a plane and a few cylinders.

We've realized that the problem may have something to do with the Intersense tracker. When we first start the tracking system, ISDemo shows a data transfer rate of about 85 kbps. As soon as Vizard connects using the intersense.dls plug-in, however, that data transfer rate drops to 16 kbps, and remains there unless we turn the Intersense system off and on again.

The Intersense version were using is an older IS-900 which connects via a serial port.

Kaminski 06-28-2011 09:29 AM

Are you running Vizard at the same time as ISDemo or IServer? That may be your problem -- we are also on an IS-900 and that was causing issues.

Also, have you tried the more recent 'intersense.dle' plugin instead?

kevin 06-28-2011 09:29 AM

Apparently Vizard is changing the mode of the tracker from 'Continuous' to 'Polled,' which is the cause of the lower data rate. Is there a way to keep this from happening?

farshizzo 06-28-2011 10:37 AM

The intersense plugin uses the official isense SDK to communicate with the devices. There doesn't appear to be any way to change the transmission mode between continuous and polled through the SDK. It appears the SDK defaults to polled for older serial-based devices.

I know the SDK supports specifying extra options through an INI config file. Maybe there is a special option for changing to continuous mode. You will need to contact Intersense about this though.

karinp 01-16-2012 01:53 AM


Originally Posted by kevin (Post 12755)
Apparently Vizard is changing the mode of the tracker from 'Continuous' to 'Polled,' which is the cause of the lower data rate. Is there a way to keep this from happening?

Hi Kevin,

I'm having the same problem with Nvis SX111...did you solve it?



chalee21 02-29-2012 01:16 PM

I am using ISDemo on a separate machine from my Vizard machine and I don't have this issue with the mode being reset to Polled.

Is someone experiencing this issue with a similar setup?

jde 09-25-2012 03:24 PM

We are experiencing this issue running ISDemo on the same machine. Has anyone resolved this issue?

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