We have analysed the formula from buildingSMART: on-line documentation:
"The circular arc is described by (see figure 1):
• R = signed Radius, if IsConvex = true, then -R, if IsConvex = false, then +R as length measure
• s0 = StartDistAlong as length measure
• z0 = StartHeight as length measure
• g0 = StartGradient as ratio measure
The following equations are used for the centre of the circular arc:
center (distance along) sc = s0 - R * s0 / sqrt(1 + g0^2)
center (height) zc = z0 + R / sqrt(1 + g0^2)
The following equations are used for any point along the circular arc:
at any point s1 along the HorizontalLength
height (IsConvex = TRUE) z1 = z0 + sqrt(R^2 - (s1 - sc)^2)
height (IsConvex = FALSE) z1 = z0 - sqrt(R^2 - (s1 - sc)^2)
gradient g1 = - (s1 - sc) / (z1 - zc) "
The formula for sc must be wrong because s0 is in meter while the other element (R*S0) in the formula is in m2 - or?