Reliable images using 1394 cameras?

[larryb]

WinXp. Labveiw 7.0. 1394 (1.5 driver).
Labview exampe: Low Level Grab for 1394.
Basler A601f camera. Problem: Horizontal frame fragmenting is easily visible when there is motion in the image.

We tried using the occurance function to over come this. No improvement.

Question 1: How to fix Labveiw example code to get reliable images of moving objects using 1394 cameras?

[ColinAE]

Hello larryb.

Thanks for contacting us. I'm not exactly sure what you mean by 'horizontal frame fragmenting,' so I will speculate that it just means that your images are skewing in some fashion when there is motion in your image.

Are you seeing this behavior when you do a grab acquisition in Measurement and Automation Explorer (MAX)? If so, what is the frame rate of your camera?

Depending on whether you see the behavior in MAX or not, we may or may not be able to do anything to the LabVIEW code to fix the issue. Take a look at your processor usage when you run the example as well to see if maybe it has anything to do with that.

Again, if you can clarify 'horizontal frame fragmenting' a little bit, as well as if you see the issue in MAX, then we can go fro
m there!

Regards,
Colin C.
Applications Engineering

[larryb]

hi Colin,

thanks for the response. i've had some time to look at the problem further.

Labview 7.1
1409 card.
640x480 progressive scan camera.
60 frames per second.
3.2 G PC with winXP pro.
upscale video monitor card.

In MAX or Labview, i was viewing a pendulum swinging at about 1 rev per 2 seconds.

The string should appear as a continous line in each image. However in some images, there is a noticable break in the line! The line has an offset of about 1/2 of its width. As time progresses, the break point migrates down the line. The images can be fine for awhile, then the progression starts again.

I wrote code to look at the pendulum in non-realtime. Again 60 fps and 640x480, however store images to memory, then play back. This way i could ex
amine the problem in slow motion. In slow motion, there is NO problem!

In fact what i was seeing was a video artifact due to the refresh rate of the PC video monitor.

Conclusin: All is well... just don't believe everything seen in realtime display. Cheers.

[larryb]

Oops, slight confusion. i've been using 1409 and firewire cameras...

the problem was actually with the firewire interface. same discussion, different interface.

sorry for the mixup.
larryb