“…The trivariate tensor-product B-spline solid (Casale and Stanton, 1985;Lasser, 1985) is a direct extension of the B-spline patch and has been shown to be useful in the creation and visualization of free-form geometric solids. The trivariate B-spline solid is defined by a set of (n x + l)x(n 2 +l)x(n 3 +1) control points {p, il2 , :0<i x <n x ,0<i 2 <« 2 ,0<i 3 <n 3 ), and three sets of knots {u Q ,u x ,...,u n+m }, {v 0 7v,,..., v" 2+m2 }, and {w 0 , w,,..., w^+ mj }, where n n n p(u,v,w) = XIZP^^^J V^^.…”