Depth measurements on the Mentor Visual iQ+ VideoProbe 

In this article:

• How depth measurement works: Mentor Visual iQ+ VideoProbe measures depth from a 3D reference plane to a target point, enabling accurate height and depth evaluation using advanced 3D data.
• Typical inspection use cases: Covers applications like blade tip clearances, corrosion pits, dents, weld height, pipe inner diameter, and gap width across critical assets.
• Accuracy and best practices: Explains features like 3D Surface Mask, Depth Assist, and point‑cloud views to improve reliability and reduce measurement uncertainty.

What depth measurements are available on the Mentor Visual iQ+ VideoProbe?

Measures the distance from a reference plane (defined by three selected points) to a fourth selected point above or below the plane.

Example Applications:

• Blade tip to shroud gaps
• Pits or dents from corrosion, erosion, or FOD impact
• Pipe inside diameter
• Weld height
• Stator vane rock
• Gap width

3D Surface Mask:

When enabled in Settings, surface points very close to the reference plane are shown in green. Surface points the same distance from the reference plane as the measurement result are shown in light blue. If the result is negative, a color gradient also highlights regions deeper than the measurement point with red indicating the deepest points.

Best Practices to Improve Measurement Accuracy:

• The measurement tip should be as close as possible to the indication to increase the accuracy of measurement.
• Position the three reference-plane cursors to maximize the coverage of 3D Surface Mask green pixels on the reference surface. If measuring a recessed point, use the color gradient to ensure that the measurement is taken at the deepest point. If measuring height or depth to a flat surface, try to maximize the amount of light blue shown on that surface.
• Check the 3D point cloud view to verify that the reference plane, indicated by a blue square, is accurately aligned with the reference surface.
• The green Surface Mask, visible when a reference plane cursor is active, indicates points very close to the reference plane. Adjust the cursor positions to maximize the amount of green on the reference surface. The 3D point cloud view can also be used to verify that the reference plane, indicated by a blue square, is accurately aligned with the reference surface.
• After the third cursor is placed, the Depth Assist feature will often automatically place the fourth cursor at the deepest point, highest point, or on a blade edge nearby. Check the position of the auto-placed cursor and adjust if necessary.
• Enable depth map mode in the point cloud view to better see surface contours and ensure that you are measuring the desired point—often the highest or lowest on an indication—and that the indication clearly stands out from the 3D data noise.
• The line projected from the depth measurement point should end near or within the triangle formed by the reference-plane cursors to minimize inaccuracy due to plane tilt.
• If you must measure at a point far outside the reference triangle, increase the size of your reference triangle to compensate (this only applies to flat surfaces, not curved surfaces).
• Use a Measurement Plane when measuring blade tip to shroud clearance and red areas along the blade edge prevent proper fourth cursor placement or 3D noise may be affecting the result. See the Measurement Plane section for details.