Two video cameras simultaneously

[AZimmer]

I am looking at setting up a new video image acquisition system and have two questions:
1/. Is it possible to use two NI PIG-8252 (firewire boards) or two NI 1426 (Camera link boards) controllers to simultaneously record images from two cameras on a single computer? The first would be supplying 30 fps at a data transfer rate of 12MBytes/sec, the second would be running a 30 sec loop where in the first second it records 60 fps for a data transfer rate of 43 MB/sec then for the next 29 seconds, once per second a full frame image is captured, each 1.4 MB. This implies burst data dump rates of 55 MB/sec every thirty seconds and "lulls" of 13MB/sec for the remaining 29 seconds. The total run time will be on the order of 4 hours, ideally continuously. We don't need to do any processing real-time, just need the images.

Based on a previous discussion I see that IMAQ is limited to using 64 MB of the RAM. So things need to get to the HD's quickly.

We propose to use a SCSI hard drive raid setup to store the data. Will this work? The PCI should handle the data transfer as they are well under the 80-100 MB/sec continuous transfer rates I have been quoted, so I think it will, but am no expert.

Will IMAQ be able to do this type of image collection?

Can it run more than one firewire or Camera Link camera at the same time? Or would we have to get two computers and two licenses of Labview &vision development module & vision builder?

Thoughts would be greatly appreciated.

[RManion]

Hi AZimmer, awesome project!

Let me check to ensure that I understand correctly. You will be acquiring from two cameras, one with a roughly 400k image size acquiring at 30 fps for a total of 12 MB/sec, one acquiring at 60 fps (for one second) and 1 fps (for 29 seconds). The only confusion I have is that it appears your image size on the second camera changes when you acquire at different speeds. Assuming the MBs/second quoted are correct, I guess that it would not matter if the image size changes.


Either way, this is definitely something that can be done using IMAQ. The RAID setup will be needed such that the Hard Drive can keep up, but the IMAQ boards should have no problem acquiring at those rates. You will need either Camera Link or Firewire cameras depending upon which IMAQ board you are looking at. Keep in mind these two things: 1) The 8252 can support a maximum of about 50MB/sec. 2) The 1426 supports Base Configuration Camera Link cameras. Make sure you get the right board/camera combination.

In terms of software, you will be using either the NI IMAQ or the NI IMAQ for IEEE 1394 Driver, based upon the board/camera you decide to go with. It should be pretty straightforward to code something like this in LabVIEW, in which you either ignore acquired images or change configuration when not saving images at the same rate.




Hope this helps!

Robert Manion
Applications Engineering
National Instruments



Additionally, I thought I would clear up the 64MB comment that was made. IMAQ is not limited to 64MB of RAM. The problem is that you cannot page-lock more than 64MB of contiguous memory, due to the Operating system. This means that sometimes you cannot acquire images that are larger than 64MB. If you do the math, you will quickly see that this only refers to images larger than 8000x8000. In short, this limitation doesn't affect many people. For those that it does affect, we have some effective workarounds.