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Stereo Measurements
Stereo measurements require the use of StereoProbe measurement
OTA's to capture stereoscopic images of a target — two pictures of the
same target from two different angles. To measure the target, the MViQ
uses triangulation based on these two side-by-side images. You can
take stereo measurements on a frozen image or on a recalled image,
provided the recalled image was saved with Stereo measurement data.
The Stereo Measurement process includes (see following sections for
details):
Step 1
– Attaching a calibrated Stereo OTA
Step 2
– Capturing an acceptable view with a suitable image as
described below.
Step 3
– Identifying the attached optical tip, selecting desired
measurement type and placing measurement cursors.
Step 4
– Properly positioning the Matching Cursors, if needed.
Achieving a Suitable Image for Making Stereo
Measurements
For maximum accuracy in any type of stereo measurement, you must
begin by positioning the stereo OTA carefully. Position the probe (before
freezing) for a Stereo Measurement Image:
Visibility—The feature must be fully visible on both sides of the screen.
Tip-to-target proximity—The OTA must be as close as possible to the
target while keeping it in focus.
Minimal glare—Minimize glare by adjusting the viewing angle and the
image brightness in the areas where you will be placing cursors. Small
glare speckles do not present a problem, but larger glare areas may
appear in different positions on the two sides, causing false matches.
Vertical orientation—If measuring distance between lines or across
a circle, the image is oriented so that you can place cursors at left
and right edges of the item to be measured — not at top, bottom or
diagonal points. The system needs differentiated details to the left
and right of each cursor to accurately place the matching cursors in
horizontal relationship to the left-side cursors.
The images above represent good and bad image capturing
techniques when stereo measurements will be made. Both images
were captured for length measurement across the slot.
About the Stereo Index
The stereo index is a number that indicates the amount of magnification
during stereo measurements. The higher the stereo index, the greater
the magnification, the more accurately you can place the measurement
cursors and the more accurate your results.
When taking stereo measurements, you magnify the image not by
zooming but by moving the optical tip as close as you can to the target.
The stereo index can be turned ON or OFF and the minimum value can
be altered (flash presented when not meeting set index value).
Click here
to learn about adjusting the Stereo Index Limit and other Measurement
Settings.
