Chapter 1 Visionscape® Overview
1-12 Visionscape FrontRunner™ User’s Manual v4.1.3, April 2012
Snapshot and Acquire
The Snapshot and Acquire steps work together to provide image
acquisition capabilities for the Job. Acquire is the image creator;
Snapshot is the image receiver.
Acquire is a special step that knows how to capture images from the
camera or disk, utilizing triggers and strobes. You can program the
camera selection, trigger, and strobe in the Acquire step. When
executing, the Acquire sets up the Camera I/O Card or Smart Camera
digitizer according to your selection and captures images into a list, called
a frame list. When an image is set into the list, the Snapshot can then pull
the frame from the list and turn it into a buffer that is then passed along to
its contained steps.
The execution of the Acquire depends on your trigger selection. The letter
“P” at the left of the Acquire step in the Job Tree means the Acquire step
is a preprocessing step of the Snapshot. Though it is a child of the
Snapshot, it is executed before the Snapshot. When no triggers are
selected (see Figure 1–8, “Job With Multiple Inspection Steps,” on
page 1-11), the Flaw Inspection tree is executed in the following order:
Acquire
Snapshot
FlawTool1
Acquire
Snapshot
Flaw Tool2
Digital Outputs Step
This changes when you select a trigger. In order to maximize image
acquisition along with inspection execution, when a trigger is selected, the
images are pipelined to the running Inspection. The hardware acquires
images from the camera when the trigger is fired using the appropriate
acquisition definition and instruct the Acquire Step that an image frame
(or buffer) is available. The Acquire Step creates a Frame Datum from the
image and pushes it onto its frame list. The Snapshot, running within the
Inspection thread, will remove the images from the frame list when it
executes. In this way, a triggered acquisition pipelines the image to the
running inspection. This allows multiple images to be captured so the
vision on the system production line does not miss parts.
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