## Accessing Information from a Constructed Scan Minimum Circle

Using PC-DMIS expressions you can pull information from a circle feature that is constructed with a given radius at a minimum point along a linear scan. See the "Constructing a Circle at a Scan's Minimum Point" topic in the "Constructing New Features from Existing Features" section for more information.

When you construct a scan minimum circle feature, the circle ultimately uses a vector (termed the down vector) to contact the scan line. It only contacts the line in two places called contact points (CONTACTPOINT1 and CONTACTPOINT2). PC-DMIS can then use these points to determine the angles from the down vector to these contact points (CONTACTANGLE1 and CONTACTANGLE2). For example, consider this diagram:

| A - The scan line to which the circle is constructed.
B - The final XYZ position of the circle's centroid.
C - The contact point to the left of the Down Vector. It is termed CONTACTPOINT1.
D - The contact point to the right of the Down Vector. It is termed CONTACTPOINT2.
E - The Down Vector.
F - The angle from the Down Vector to CONTACTPOINT1. It is termed CONTACTANGLE1.
G - The angle from the Down Vector to the CONTACTPOINT2. It is termed CONTACTANGLE2.

The expressions detailed in the table below will only function with this type of constructed circle feature. You can also use CONTACTPOINT2 in the syntax below to return the equivalent information using the second contact point instead.

Expression Syntax

Expression Example | Description
ASSIGN/V1=CIR1.CONTACTPOINT1.XYZ | Returns the XYZ point information for the circle's first contact point with the line, CONTACTPOINT1.
ASSIGN/V1=CIR1.CONTACTPOINT1.X | Returns the X information for CONTACTPOINT1.
ASSIGN/V1=CIR1.CONTACTPOINT1.Y | Returns the Y information for CONTACTPOINT1.
ASSIGN/V1=CIR1.CONTACTPOINT1.Z | Returns the Z information for CONTACTPOINT1.
ASSIGN/V1=CIR1.CONTACTPOINT1.IJK | Returns the IJK vector from CONTACTPOINT1 to the circle's centroid.
ASSIGN/V1=CIR1.CONTACTPOINT1.I | Returns the I value from the above CONTACTPOINT1 IJK vector.
ASSIGN/V1=CIR1.CONTACTPOINT1.J | Returns the J value from the above CONTACTPOINT1 IJK vector.
ASSIGN/V1=CIR1.CONTACTPOINT1.K | Returns the K value from the above CONTACTPOINT1 IJK vector.
ASSIGN/V1=CIR1.CONTACTANGLE1 | Returns the angle from the Down Vector to CONTACTPOINT1.
ASSIGN/V1=CIR1.CONTACTANGLE2 | Returns the angle from the Down Vector to CONTACTPOINT2.
ASSIGN/V1=CIR1.CONTACTANGLE | Returns the sum of the absolute values of CONTACTANGLE1 and CONTACTANGLE2. It should be no greater than 180 degrees.