Case Studies
Image Acquisition from Three Analog Cameras
THE PROBLEM
The customer is using three independent cameras made by Cidtec. These cameras provide an analog output as well as a pixel clock (of up to 10 MHz). It is assumed that FRAME_START and LINE_START signals are also provided. All digital signals are TTL levels.
These cameras also have the ability to zoom in on a portion of the image to provide better resolution. These smaller images can be output by the camera at rates up to 200 to 300 Hertz. The full frame can be output at rates up to 30 Hertz.
The customer needs to acquire and analyze one of the full frames (512 x 512 pixels) to determine which portion of the image should be zoomed in upon. Once that is determined, a controller card in the PC (ISA bus card) is used to tell the cameras which portion of the image to zoom in on.
Once the cameras are zoomed in, one image from each of the cameras needs to be captured and analyzed.
It should be noted that the cameras may be zoomed in to totally different sections of the image; thus the trigger from each camera will be completely independent. This requires three separate triggers for the system.
It is also important to note that the data acquisition system does not have to keep up with the 200 or 300 Hz frame rate.
GAGE'S SOLUTION
The solution to this problem is a Multiple/Independent Three-board CompuScope 1012/PCI system to acquire data from the cameras, i.e., one CompuScope card per camera.
Start of acquisition will be signalled by the FRAME_START signal, which will be injected into the External Trigger input of the CompuScope card.
The customer will start the testing session by using on-board memory to acquire an entire frame of 33 milliseconds. The amount of on-board memory needed is 330 kilosamples, as shown below:
Record Length = 33 ms / 100 ns = 330 kilosamples
A CompuScope 1012/PCI-1M board has 512Kilosamples of on-board memory available per channel and is more than sufficient for this data storage.
In software, the customer will be able to analyze the image and come up with the result. He will then set the Cidtec parameters accordingly.
The resulting "smaller" image is then captured using the same CompuScope cards. The only difference is that the image capture time is a lot shorter (5 milliseconds for a 200 Hz frame rate), and, therefore, record length is also much shorter.
Shorter Record Length = 5 ms / 100 ns = 50 kilosamples
Once again, software can analyze this image and come up with the result.
The customer's software would be using the source code DOS drivers supplied by Gage, which support Multiple/Independent boards. A sample program called GAGEINDX.C is supplied with these drivers. This program sets up the independent boards in slightly different configurations (to show they are indeed independent) and displays the resulting data on the screen. In this customer's case, the data is not to be analyzed and not displayed.
We also suggested to the customer that they house the three CompuScope 1012/PCI cards in one of our Industrial Grade PCs, GagePC 586. This is a ruggedized, P200 based industrial grade PC based on a passive backplane and a high speed PCI/ISA CPU card. By installing and testing the cards ourselves in our rugged GagePC 586, the customer can expect his system to work right out of the box, providing a turnkey solution.
PRODUCT RECOMMENDED
Turnkey System:
- Three CompuScope 1012/PCI Cards, each with 1M of on-board memory
- Housed in a GagePC 586 Industrial Grade PC
This application note is provided "as is" without any warranties of any kind, either expressed or implied, including but not limited to the implied warranties of merchantability or fitness for a particular purpose. Gage Applied Technologies further does not warrant the accuracy and completeness of the material contained herein. Gage Applied Technologies may make changes to this material, or to the products described in it, at any time without notice.
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