CPU load firewire and USB cameras

[Cyphre]

I need to select a camera system for use on a pc with two or three cameras streaming active at the same time. This PC also needs to run automated stages so this PC needs resources available.

From reading the Choosing the right camera bus article it would seem that firewire cameras are the most suitable while still being cost effective. Howerver my tests of comparing USB and firewire cameras available to me here show that the firewire camera consumes 65% of the CPU resources that the USB camera coonsumes. I ran this test using IMAQdx with the firewire camera and the USB acquire with the USB camera in NI vision assistant software. I had the same framerate and  resolution settings in this test. I expected a lower than 65% of the USB camera overhead for the firewire camera, so is this an accurate comparison for these two camera bus technologies?

Also in the "choosing the right camera bus" article it states that GIge-vision cameras consume very little cpu reources when used with optimized drivers for the NIC,  so how little reources compared to a firewire camera would an optimized Gige camera use?

[Andrey_Dmitriev]

Usually USB cameras are working at low resolution. Firewire usually medium to high res. So, for clear comparison you should compare the cameras with exactly the same image size, image depth and frame rate. Also it depends from card's producer, for example CPU usage by camera link grabbers from NI or Matrox may differ.

But for right choosing you need to define requirements for size and resoultion, color depth, sensitivity and how far away camera from PC. If you need distance more than 10-15 meters, then GigE or IP cameras most suitable for you. If you need high resolution and frame rate, then camera link or firewire and so on. Once you have such requirements, then you can choose appropriate bus for your camera.

Andrey.

[Intaris]

What resolutiona nd frame rate were you using?

USB requires action from the CPU for the data transfer.  At lower frame rates or resolutions the difference between the two will be small but moving up to more dta being transferred will see the differential growing.

Shane.

[Cyphre]

I ran the tests at 800*600 and 1024*768 with 8 bit depth and 10 frames per second.

Im more interested in the differances between firewire and Gige-vision. Cable length is not an issue. I need about 20 fps and resolution around 1024*768 and most important is to lower the cpu resources consumed. Could I expect a Gige vision camera to consume less than a Firewire camera?

Also how important is the particular driver supplied with the firewire camera, I have two different firewire cameras to hand, from different companies and both seem to consume very different amount of cpu resources for same resolution and framerate?