how to acquire images with two webcams at the same time?

[liaw82]

Hi,

Is there a way to make use of the USB webcame driver to acquire images from two different webcams at the same time?

I wish to have two windows that show the same acquired images simultanously..

Any comments are welcome..

thx

[RManion]

Hi liaw82,

How's it going? The webcam driver should be able to use two USB cameras simultaneously. You can use the IMAQ USB Enumerate Cameras program to identify each camera plugged into your system.

That said, there have been some problems using two identical USB cameras at the same time. Each USB camera has its own software and behaves slightly differently. In house, we were using Creative WebCam Instant and had no problems using two identical cameras. In customer use, we have found that some do not behave identically.

Give the IMAQ USB Enumerate Cameras VI a try, and if it doesn't work, let me know.

Hope this helps, have a great afternoon!

Robert

[liaw82]

Hi RManion...nice to meet u..

I tried with the IMAQ USB Enumerate Cameras to call out 2 identical cameras (Creative Live pro!) and initialize them and "IMAQ USB Grab Setup" them initially. Then I used two "IMAQ USB Grab Acquire.vi" to acquire two images from two cameras. But it doesn't work as acquisition can only be performed for one device at a time..

So I tried "IMAQ USB Stop.vi" to stop the acquisition of first camera after acquisition and "Grab Setup" the second camera. Then I stop the second camera again and setup the first camera. Both cameras can acquire images but the processing time is very very very very very very long..

Do u have any idea? or is there any sample code for reference?

thx for ur help..

p.s. I attached a sample of mine for u to have a look..thx..

Message Edited by liaw82 on 05-24-2005 06:29 AM

[RManion]

Hi again Liaw82,

I double checked on this, and it turns out that *simultaneous* acquisition from two cameras is not supported by the IMAQ for USB driver. You can see that this is the case at the top of page 6 in the IMAQ for USB Documentation. (The documentation is included in the IMAQ for USB .zip file) Note that you can still use the software with multiple cameras, but multiple cameras cannot simultaneously acquire.

Hope this helps,

Robert

Message Edited by RManion on 05-26-2005 04:16 PM

[liaw82]

Hi RManion,

Unfortunate to hear that cause my objective is to implement triangulation to calculate 3D position of an object... never mind and thx anyway...

[RManion]

Sorry to hear that liaw82! Keep it mind you can still accomplish this with another type of camera, just not USB.

Good luck,

Robert

[Ancle]

There is a same question and answer. Please check it out.
http://forums.lavausergroup.org/index.php?showtopic=1244&hl=usb