multiple USB cameras in Labview

[MikeS81]

Hi Marzero0,

how did you try it? How often do you need a new picture? I think you first has to store the image in a web server supported control (if you use the ni web server).

Mike

Message Edited by MikeS81 on 01-28-2009 02:56 PM

[Marzero0]

Hi MIke,

Id tried with the "web server" tool, describes in this document:

http://digital.ni.com/public.nsf/allkb/7F95D43D3F50FCAC8625710E000068E1?OpenDocument

It works with others VI that has no webcams and with VI using IMAQ (just for one webcam..thats the problem). But using avicap32.dll doesnt work =(

I want images faster as it can (20 ms could be great). Now im learning about web service tool to see if it helps. Thanx a lot again.

Marzero0

[MikeS81]

Hi Marzero0,

i'm not sure, but maybe a .Net control will be visible in the Web VIEW. See this example to see how to use a .NET picture control. Connect this handle to the "avi..." function instead of the handle of the front panel window.

Hope it helps.

Mike

[FakStory]

hi there,

               This is an amasing VI that work perfeckly. Nevertheless, I can't take picture directly from NI vision...? Can I use a usb camera with Ni vision? If not, can I build a process in NI vision and after that put it in this example? But it would be great that NI vision reconized my camera... any idea?

Fakstory

[MikeS81]

Hi Fakstory,

i'm not sure, but maybe this driver helps.

Mike

[FakStory]

Mike,

           You're awesome!!! This was exactly what I needed!! Maybe you can stop to begin your post with "I not sure, but maybe..."  cause you actually did it...

Very helpful dude!

Fakstory

[Curiouspuya]

Hi Mike and thanks,

Im still having trouble getting two cameras to work.  The driver you cited is not capable of running more than one device at a time (according to NI).

I came across a program by a third party developer called Ivision.  Im trying to get the evaluation version to work but to no avail:

http://www.hytekautomation.com/Products/IVision.html

Regards,

Puya

[Marzero0]

HI!

Its me again. The VI that "Curiouspuya" links works with Directx driver, i think this works with multiple cameras (I opened VI multiple times and changing the source video and it works) You just have to change the code to have multiple cameras. I saw that are tutorials for work with Directx in Labview. See:

http://zone.ni.com/devzone/cda/tut/p/id/2983

On the other hand, i think this is not gonna work for the web publishing, cos the windows that opens this drivers (Avicap and Directx) is not embedded in the VI and it will be not shown on the web. Maybe there's a way to enbedded in to the VI...maybe..

Regards.

Marcelo.

[FakStory]

Did you try to launch your process in thread? I mean, each camera in two different process?

-with the launch a vi from property node, 

-or simply with two subvi with the "reentrant" option check (in the application menu (I think) after a "ctrl" + "i")

I already seen the kit you're talking, but it's not free, and I guest they simply found a way to run more than one camera... But, if you are able to read something from one camera, you're not so far...

If the reentrant option didn't work, try to build a dll, which is a share ressource for your cameras...

In an other hand, if your picture/second is not critical... Maybe you can "timed" your snap in series...take one picture from one camera, then with each other one, and loop it.

Hope this help, I already got some problem with that, and we just abord the project, so, I want you to got it...

Fakstory

[Curiouspuya]

thanks guys,

Well the program I mentioned is not free but still works without registration.  Its just that it keeps giving messages about registring. I have tried to use it but couldnt get two images with that either.  i wrote to the creator of the program and she told me that i may have issues with USB bandwidth limits and that since I am using a laptop, it may not be possible to get two cameras at the same time. 

The thing is, i can get images from both cameras with no trouble if I just use the camaras vendor supplied program and bring down the USB bandwidth.  So i know its theoretically possible.  I just wonder how labview can be configured to run it.  i am very surprised that NI does not provide a solution for this.  It is obviously a very useful process and many people would like to use it in their projects. 

I could try what Fakstory suggested, ie to get one image at a time seperately. but i imagine that would make the sampling very slow.  and i dont know how resource heavy that would be since you are continously opening and closing camera sessions.  but i will give anything a go.

all the best guys

puya