Polygons > Decimate reduces the number of triangles without compromising surface detail or color, useful when the object contains an excessive number of points.
Decimation can be performed on a selected area or to the entire object.
The controls on the Decimate Polygons dialog are:
Reduction Mode group - specifies the algorithm for point reduction:
Triangle Count radio button (the default) - maintenance of the object’s shape is the highest goal.
Tolerance radio button - as the triangle count is reduced, the surface is allowed to shift by a user-specified maximum.
Mode-Specific Parameters group
(When Reduction Mode is Triangle Count) pick one of the following:
Target Triangle Count - specifies the number of triangles in the object (or selected area thereof) at which the decimation process will terminate. The default is the current number of triangles, meaning that no decimation occurs.
Reduce to Percentage - specifies the percentage of existing triangles to be maintained during decimation; must be 100 or less
(When Reduction Mode is Tolerance) pick one or both of the following:
Maximum Tolerance - specifies the greatest distance allowed between any original vertex and the position of the new polygon mesh. A given vertex might be eliminated, thus causing a shift in the polygon mesh. The vertex would not exist on the new mesh, but a distance from the original vertex to the new mesh is calculated. This parameter specifies the maximum “shift” that is allowed during decimation. (Tools > Options > Operations > Wrap > Decimate > Tolerance Outlier Percentage specifies the percentage of original vertices whose “shift” is allowed to exceed this maximum.)
Lower Triangle Limit - specifies the number of triangles in the object (or selected area) at which the decimation process will terminate, preventing the triangle count from getting too low.
Fix Boundaries checkbox - specifies whether to maintain density of points at the edges, useful because edges often require maximum precision.
Advanced checkbox - activates the Advanced group of controls.
Advanced group - controls for advanced users.
Curvature Priority checkbox and slider - (Min to Max) the higher the setting, the greater the uniformity of the resulting mesh.
Mesh Priority checkbox and slider - (Min to Max) The higher the setting, the greater the uniformity of the resulting mesh.
Maximum Aspect Ratio group - guarantees a proportionality of resulting triangles. Some CAE application require that both Edge/Edge and Edge/Height length ratios be less than or equal to 10.
Edge/Edge checkbox and decimal field - the highest allowable ratio between any two edges of one triangle. “10.0” means that no edge can be more than ten times longer than another edge of the same triangle.
Edge/Height checkbox and decimal field - specifies the highest allowable ratio between any of three edges and any of three heights. “8.0” means that no edge can be more than eight times longer than any of the triangle’s three heights.
Color Decimation group (appears only when the object has color) -
Enable checkbox and Color Priority slider (applicable when Reduction Mode is Triangle Count) - specifies whether to preserve colors during decimation, and the degree to which color preservation is a priority.
Apply button - executes the decimation process.
Statistics group (appears only when Reduction Mode is Tolerance) - presents details about the resulting object.
Current Triangles - the number of triangles in the decimated object.
Maximum Tolerance - the greatest distance that any point moved. This indicator cannot exceed Maximum Tolerance parameter.
Actual Outlier Percentage (appears only if value is non-zero) - indicates the actual percentage of original vertices whose “shift” exceeded the Maximum Tolerance setting (as allowed by the setting at Tools > Options > Operations > Wrap > Decimate > Tolerance Outlier Percentage).
OK button - replaces the original object in the Model Manager with the decimated object.
Cancel button - terminates the dialog without saving a decimated object.
Reset button - reverts the polygon object to its non-decimated condition.