Method for fast calculating the nearest distance from spatial point to STL model

For fast calculating the signed distance from spatial point to STL model, a reference ball method was put forward based on linear octree. The method divided a set of triangular patches into linear octree's different nodes by partitioning linear octree. Triangular patches were connected with terminal nodes of the linear octree, then the range of triangular patches was reduced by reference ball, thus the distance can be calculated fast from spatial point and STL model. The experimental results show that the proposed approach can get the nearest distance from spatial point to STL model fast, moreover, the approach can be applied to the cases for calculating a great deal for distances.