# Differences

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 rhino:nurbssurfaces [2015/09/14]127.0.0.1 external edit rhino:nurbssurfaces [2016/01/13] (current)sandy 2016/01/13 sandy 2015/09/14 external edit 2016/01/13 sandy 2015/09/14 external edit Line 1: Line 1: - ** [[rhino:nurbs|NURBs]] Surfaces Concepts ​** + ======NURBS Surfaces Concepts====== + + > **Summary:** //Basic concepts of NURBS surface geometry// - > **Summary:​** //Basic concepts of [[rhino:​nurbs|NURBs]] Surfaces Geometry// \\ \\ - + One of the main geometry concepts that comes up often when modeling with Rhino is [[rhino:​nurbs|NURBS]] curves and surfaces. ​ Non-Uniform Rational Basis Spline (NURBS) is an accurate mathematical representation of curves and surfaces. The shape of the surface is defined by a number of control points and the degree of that surface in each one of the two directions (u- and v-directions). Refer to Rhino Help Glossary for more details. - One of the main geometry concepts that comes up often when modeling with Rhino is [[rhino:​nurbs|NURBs]] curves and surfaces. ​ Non-Uniform Rational Basis Spline ( or [[rhino:​nurbs|NURBs]] for short) is an accurate mathematical representation of curves and surfaces. The shape of the surface is defined by a number of control points and the degree of that surface in each one of the two directions (u- and v-directions). Refer to + - + - Rhino Help Glossary for more details. + \\ \\ Line 12: Line 10: \\ \\ - [[rhino:​nurbs|NURBs]] surfaces can be trimmed or untrimmed. Think of trimmed surfaces as using an underlying [[rhino:​nurbs|NURBs]] surface and closed curves to cut a specific shape of that surface. Each surface has one closed curve that define the outer border (//​OuterLoop//​) and as many non-intersecting closed inner curves ​to define holes (//​InnerLoops//​). ​A surface with outer loop that is the same as that of its underlying [[rhino:​nurbs|NURBs]] surface and that has no holes is what we refer to as **untrimmed surface**. + [[rhino:​nurbs|NURBS]] surfaces can be trimmed or untrimmed. Think of trimmed surfaces as using an underlying [[rhino:​nurbs|NURBS]] surface and closed curves to cut a specific shape of that surface. Each surface has one closed curve that define the outer border (//​OuterLoop//​) and as many non-intersecting closed inner curves ​that define holes (//​InnerLoops//​). ​We refer to a surface with outer loop that is the same as that of its underlying [[rhino:​nurbs|NURBS]] surface and that has no holes as **untrimmed surface**. \\ \\ Line 18: Line 16: \\ \\ - The surface on the left is untrimmed. The one on the right is the same surface trimmed with an elliptical hole. Note that the [[rhino:​nurbs|NURBs]] structure of the surface doesn’t change when trimming. + The surface on the left is untrimmed. The one on the right is the same surface trimmed with an elliptical hole. Note that the [[rhino:​nurbs|NURBS]] structure of the surface doesn’t change when trimming. \\ \\ - A polysurface consists of more than one surface joined together. Each of the surfaces has its own u- and v-direction; therefore, paneling using uv-directions may not continue the paneling pattern across the polysurface edges. Paneling commands can either use surface uv-directions or follow a specified direction. + A polysurface consists of more than one surface joined together. Each of the surfaces has its own u- and v-direction. Thus, paneling using uv-directions may not continue the paneling pattern across the polysurface edges. Paneling commands can either use surface uv-directions or follow a specified direction. \\ \\