Understanding Computer-Aided Engineering and Reverse Engineering

What is Computer-Aided Engineering (CAE)?

CAE formalizes ideas through computer modeling and then fabricates the models into real-world objects through CAD and CAM.

What is Computer-Aided Reverse Engineering (CARE)?

CARE works in the opposite direction. CARE creates a computer model of an object through measurements of the object as it exists in the real world. CARE is the reversal of CAE.

What is a Coordinate Measuring Machine (CMM)?

• Coordinate Measuring Machines (CMMs) are a practical means for characterizing and inspecting free-form surfaces.
• Coordinate Measuring Machines (CMMs) first appeared in the early 1960s.
• A CMM consists of a probe supported on three mutually perpendicular (x, y, and z) axes, and each axis has a built-in reference standard.
• The probe allows accurate measurements along each axis relative to the standard.
• CMM generates 3-D coordinate points as the probe moves across a surface.

How does a CMM Execute Path Planning?

Advanced CMM systems allow operators to upload a CAD model of the object.

The CMM then uses this model for path planning.

How does Stereovision Work?

To acquire 3-D information, the most well-known methodology is Stereovision, in which two cameras operate in a manner similar to human eyes.

Stereovision Drawbacks and Solutions

The major drawback of stereovision is the need to establish correspondence between a point in one camera’s image and the same point in the second camera’s image.

If we can establish this correspondence, we can construct an accurate image.

One way to overcome the correspondence problem is to control illumination in an intelligent manner and thus simplify the correspondence search.

Such a method is known as active illumination stereo, or simply active stereo.

What is Passive Illumination Stereo?

Passive illumination stereo refers to the measurement of visible radiation that is already present in the scene.

Approaches to Controlling Illumination

Continuous wave modulation, time-of-flight estimation, structured-light triangulation.

How Time-of-Flight Estimation Works

The system measures the time required for a laser pulse to travel to and return from an object.

Steps for Laser Range Scanner 3-D Data Capture

Data collection, mesh reconstruction, surface fitting.