Intelligent Measurement Processes in

3D Optical Metrology:

Producing More Accurate Point Clouds

21st century = explosion in the ability to measure

Also true for metrology...

Measuring Systems - History

CERN

Technological Advances

Measuring Systems

Each experiment generating

terabytes of observation data!

Each experiment generating

terabytes of observation data!

Intelligent Measurement

• What is it?

– A way to improve the accuracy of

measurement by producing consistent

measurements from several observations.

– Acquisition model of the system is

integrated within the continuous measurement

process.

•Reading an ambient temperature of 60°C in a conference room…

•Reading a diameter of 100 mm for a coin…

Intelligence would lead to a

second measurement...at least...

Intelligence would lead to a

second measurement...at least...

3D Optical Metrology

• Metrology

– Inspect parts by extracting measured characteristics

from geometrical entities (circles, planes, etc.)

– Based on a limited number of calculated points

• Optical Sensors

– Produce a very large number of observations (20,000

to 1,000,000)

– This allows better definition of the surface

– This also allows local characterization of the error

Intelligent Measurement - Presentation

1. 3D Optical Metrology

2. Producing 3D Points

3. Acquisition & Calibration Model

4. Framework for Intelligent Measurements

5. Application of Intelligent Measurements

Observations to 3D Measurements

• Raw points = 3D point clouds from a sensor?

• Not raw observations…...They are the result of several calculations

– Example: CMMBasic observations are collected from the linear or angular encoders

Producing 3D Points - CMM

The 3D points are the result of

calculations from the parameters of

the acquisition model of the device.

Linear and

angular encoders

Observations to 3D Measurements

• In any measuring systems, all points are

calculated… Only the nature of those

calculations changes.

Producing 3D Points – Intelligent

Measurement

The 3D points are the result of

calculations from the parameters of

the acquisition model of the device.

CCD

2D subpixel

positions

Again...

Acquisition & Calibration Model for

Intelligent Measurement

Example: Impact of the angle of incidence

Framework for Intelligent

Measurements