Locate Deviations Between Entities

The engines that individual CAD systems use to generate geometry can produce models that vary from system to system. If your precision applications require that you import information from other packages, you may need to identify deviation between imported entities and their Mastercam counterparts. Mastercam 2025 now includes deviation analysis that allows you to compare any combination of points, curves, surfaces, bodies, and faces.

The new Analyze Deviation function analyzes the differences between different kinds of entities and applies a color-coded “heat map” to the geometry to display deviations within the graphics window.

Find this new function on the Home tab in the Analyze group.

A drop-down menu from the ribbon control presents you with five different combinations of entities to create a comparison:

• Surface to Surface

• Curve to Surface

• Point to Surface

• Curve to Curve

• Point to Curve

Select an option and follow the prompts to open the function panel.

You can customize the results that display in the graphics window by manipulating the options in the function panel.

• Change the Point Grid (Surface to Surface—an analysis between surfaces, bodies, and faces) or the Point String (Curve to Surface, Curve to Curve) values to increase or decrease the density of points displayed in the graphics window.

• Choose to ignore deviations less than a specified deviation tolerance.

• Show or hide deviations in specific ranges. (Useful if you just want to show positive or negative deviations)

• Reverse the colors representing the deviation ranges.

• Select a new option from the Deviation Type drop-down menu in the panel and follow the prompts to change the entities you are analyzing. There is no need to exit the function.

Mastercam displays ranges of deviation between the reference and target entities according to the Deviation Legend at the bottom of the panel, with maximum positive and negative deviations represented by the large blue or red dots, as shown in the image below. Hover over these or any of the points displayed by the function to read the deviation value of that point.

The function calculates deviation distances along the surface normals. When applied to curves, the normal vectors displayed from the reference to the target represent the degree of deviation. The longer the vector, the greater the deviation.

Practical application

If you are working with geometry that needs to match an existing curve or surface, you may decide that you can simply lower the maximum surface deviation tolerance during construction to match the target. If lowering the tolerance is not an acceptable option, the deviation results can help you produce a more accurate fit. Once you know the locations of maximum deviation, you can introduce additional curves or points at these points. For example, if you are lofting a surface through a sequence of curves, you could extract constant parameter curves from the existing surface at those locations to minimize the deviation. An acceptable fit may require several rounds of construction and deviation analysis.