Polygons > Average Polygon Objects creates a new “super reference” polygon object that is the average of two or more originals. The result appears in the Model Manager. The purpose is to create a reference object that is better than any of several imperfect objects.
To create an average object, select two or more polygon objects in the Model Manager and click Polygons > Average Polygon Objects. Typically, accept the defaults and press Apply to compute the object, then OK to save it in the Model Manager.
The controls are:
Name - (default Average N) specifies the name of the resulting averaged object.
Advanced Options checkbox - exposes the following controls that affect the computation of average:
Reference - specifies which of several originals is considered to be the reference object. Deviations of the other object(s) will be calculated with respect to the reference object. “Minimum Deviation” in this field (the default) automatically selects the one polygon object among several that is already closest to the average of all.
Parameters group
Max Deviation - limits the amount of positional change to vertices of component polygon objects.
Preserve Mesh checkbox - calculates average object faster, but allows self-intersecting triangles on the resulting object which may limit its subsequent use.
Weighted Average checkbox - [as opposed to “direct average”] specifies whether to assign more weight to vertices that occur more often near the same position among the multiple objects, potentially reducing the effect of outliers.
Display Deviations checkbox - causes a graphical analysis of component objects to appear in the Viewing Area. The analysis appears after you press Apply to perform the averaging. This analysis helps the user identify any “bad” objects that should be eliminated from the averaging process. If a “bad” object is found, press OK and re-start the function without selecting the bad object from the Model Manager.
Deviation Type dropdown (Min Error, Avg Error, Max Error, or Distance) - specifies the type of deviation that is color-coded in the Viewing Area.
Sort by dropdown (Name, Statistical Maximum, Stat. Avg., or Stat. Std. Deviation) - specifies the order in which original objects appear in the Ordered List below. The order does not affect the computation, but helps the user peruse the list in meaningful ways.
Invert checkbox - causes the order of objects in the Ordered List to reverse.
Ordered List of Original Polygon Objects - lists the objects that are components of the average (the same objects originally selected in the Model Manager). Their order does not affect the graphical display or the next computation. The purpose of the list is to help the user identify a “bad” object. The following controls do not affect the averaged object, but assist in selection of the components of the graphical display to help the user identify a “bad” object. In addition to the following buttons, use the mouse to highlight the names of objects that you want to be included in the graphical analysis.
Up and Down arrows - assist in the selection of objects that are components of the graphical analysis.
Select All button - causes all listed objects to be components of the graphical analysis.
Edit Spectrum checkbox - specifies whether to allow editing of the deviation spectrum bar in the Viewing Area. See All About Spectrums.
(When the dialog is closed, the averaged object remains in the Model Manager but this statistical data disappears.)
OK button - stores the most recently computed averaged object in the Model Manager and terminates the dialog.
Cancel button - closes the dialog without saving an averaged object in the Model Manager.
Apply button - computes an averaged object based on parameters in the Advanced Options area. If Display Deviations is checked, a new graphical analysis appears in the Viewing Area. The dialog remains open for possible recomputation. If the most recent averaged object is acceptable, click OK.