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Measurement Plane (3D Phase and 3D Stereo)
A Measurement Plane is not a standalone measurement type and gives no result. When used with specific measurement types, the Measurement Plane
allows cursor placement in red areas where no 3D data is present or where noise in the 3D data may reduce measurement accuracy.
Once placed, a Measurement Plane establishes a 3D plane aligned with a flat area on the surface of the viewed object. The plane mathematically
extends beyond the edges of the surface over the entire image. The presence of a Measurement Plane affects specific measurement types as follows:
• Length, Point to Line, Multi-Segment, and Area: All cursors are projected onto the Measurement Plane, and the result is computed using the projected
positions on the plane.
• Depth: The first three cursors select individual surface points as with a normal Depth measurement. Only the fourth is projected onto the Measurement
Plane.
• Depth Profile: The Measurement Plane is used as the reference plane, so the Depth Profile cursors may overlap edges or be in red areas. The resulting
dimension shows the height or depth from the Measurement Plane. Use only with flat reference surfaces.
• Area Depth Profile: Both reference lines are positioned on the Measurement Plane allowing them to pass through red areas or surface pits without
affecting the profiles taken between the reference lines. The resulting dimension shows the height or depth from the Measurement Plane. Use only with
flat reference surfaces.
Applications for Measurement Plane usage include:
• Area measurement of a missing corner with a cursor placed in space where the corner used to be.
• Point-to-Line measurement of missing corner or indication along an edge where a lack of 3D data or data artifacts prevent proper cursor placement.
• Length or Point-to-Line measurements of small features on flat surfaces when 3D data noise is significant relative to the feature size. This often occurs
when the tip cannot be moved close enough to the indication to achieve better data quality.
• Depth measurement of turbine blade tip-to-shroud clearance where 3D data along the edge of the blade is missing or exhibits artifacts. This is often
due to large MTD. Measurement may be accomplished by placing the Measurement Plane cursors on the face of the blade, the first three Depth cursors
on the shroud, and the fourth Depth cursor on the edge of the blade near the Measurement Plane.
• With Area Depth Profile when measuring a field of pits on a flat surface.
Note:
Because the fourth Depth cursor is projected onto the Measurement Plane, DO NOT select a Depth measurement type with a Measurement Plane
to measure pits or dents.
Note:
Once a user-defined Measurement Plane is added to an image, all measurements added before or after the plane was inserted utilize the
Measurement Plane.
