National Instruments NI myRIO, Essentials Manual

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18 CHAPTER 3. DESIGN PATTERN FOR MACHINE VISION APPLICATIONS
how to use NI-MAX while configuring Vision Acquisition to select the
webcam resolution (mode) and attributes.
2. (image) analyze – (image) analyze
33
– Use the Vision Assistant Express VI
to load the script created during development with the stand-alone Vision
Assistant tool, select the necessary options to create an image buffer for the
analyzed image (allocates memory only on the first run), and then select
the necessary controls and indicators so that the script inputs and outputs
can be merged into the data highway. The Express VI requires a reference
to the webcam image buffer as its input and generates a reference to the
analyzed image buffer as its output.
Most Vision Assistant script steps produce clusters or arrays that are not
available as standard front-panel controls when editing the data highway,
however, it is very easy to create a custom control that can be added to
the data highway; see
Add Custom Data Lane
34
for details.
3.
(image) overlay
– (image) overlay
35
– use
IMAQ Overlay Text
to add a
nondestructive information overlay to an image buffer. This is a relatively
simple example, but is illustrative of the general technique to add overlays.
LabVIEW provides a wide variety of VIs to create overlays.
4. (image) show – (image) show
36
– update the main image display using
any of the available image buffers; the Select node and a mode button
are illustrated here.
33
http://youtu.be/mKuwsgGs7sY
(2:23)
34
http://youtu.be/GkqjZCj3xck
(2:58)
35
http://youtu.be/Vmony2qtnH8
(3:12)
36
http://youtu.be/LrjuylUE_4Q
(1:31)