The described tools are able to detect plain and cylindrical surface patches, so these are the two existing kinds of surfaces.

Figure 8: An object with

The addition of more surface models, if corresponding detection tools are developed, is intended.

Both surface types are bounded by edges, so they are described by a closed loop of edges. This means that the end of one edge is the start of the next one. The end of the last edge is the start of the first.

Figure 9: Example for the surface type

**Plane Surfaces** are finite parts of a plane.
An infinite large geometric plane is cut in two parts by a closed
loop of edges (Figure 9).
The parts with the finite area is the inner side.
All bounding edges and their vertices are in this plane.
The orientation of **Circular Edges** is identical to the surface normal.

Figure 10: Examples for the surface type

geometry | circular edges | radii | straight edges |
---|---|---|---|

cylinder | circles | equal | virtual |

cylinder segment | arcs | equal | straight or rounded |

cone | circles | one equals zero | virtual |

Cone segment | arcs | one equals zero | straight or rounded |

frustum | circles | unequal | virtual |

frustum segment | arcs | unequal | straight or rounded |

**Cylindrical Surfaces** (Figure 10) are defined as follows:

- They consist of two
**Circular Edges**. If the**Circular Edges**are arcs, we say it is a segment. In this case the arcs are connected by**Straight**or**Round Edges**, otherwise the connections are**Virtual Edges**. - The centers of the
**Circular Edges**are forming the axis and both**Circular Edges**are perpendicular to this axis. - One of the
**Circular Edges**may have radius zero. In this case we say it is a cone.

The number of surface types is not restricted. If a new tool for detecting a certain structure in the range data is developed, a new surface model may be added.

Last updated 1997/07/11, © Jochen Duckeck