Size dimension UAME not matching max_insc/min_circsc diameter

I may be misunderstanding something but does anyone know why the ASME Y14.5 UAME size often doesn't match the maximum inscribed diameter on IDs and the minimum circumscribed diameter for ODs? Conceptually I'd assume they would be the same. The run below is from version 2018 R2 SP 14, changing from 2D to 3D circle doesn't change the result at all

ID_SCAN    =BASICSCAN/CIRCLE,NUMBER OF HITS=2130,SHOW HITS=NO,SHOWALLPARAMS=NO
            ENDSCAN
            MOVE/CLEARPLANE
ID_DIA     =FEAT/CIRCLE,CARTESIAN,IN,MAX_INSC,NO
            THEO/<0,0,-2.184>,<0,0,1>,3.415
            ACTL/<-0.0002,-0.0002,-2.184>,<0,0,1>,3.4138
            CONSTR/CIRCLE,BF,2D,ID_SCAN,,
            OUTLIER_REMOVAL/ON,3
            FILTER/ON,UPR=50
ID_SIZE    =SIZE/
            OUTPUT=BOTH, UNITS=IN, STANDARD: ASME Y14.5,
            NOMINAL SIZE: 3.415,
            UPPER TOLERANCE: 0.001,
            LOWER TOLERANCE: 0.001,
            UAME SIZE: 3.4141,
            LOCAL SIZE: 3.4145,
            FEATURE: ID_DIA

SingularitY over 2 years ago

Have you tried dimensioning a least squares circle using Size? It's supposed to disregard the algorithm and report out correctly, but I've never used an inscribed circle for Size.
UAME is supposed to mimic a pin gage and should match inscribed, but Local size may not because it isnt really a circumscribed construction. Circumscribed used the furthest 3 points, Local size does the furthest 2 point diameter, like a caliper or bore gage.
I also noticed you are using a gaussian filter and outlier removal. I'm not at my computer so I can't confirm if Size disregards filtering, but I would hope not.
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Krisj over 2 years ago

Dimensioning a least squares circle did not change the result from the size dimension. If I turn off the filter and outlier removal the size dimension UAME matches the feature max_insc size, turning it back on causes the size dimension to change back but doesn't change the size of the constructed circle. So it seems the constructed circle size may be the problem, I'm not sure why it doesn't update as well
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