Interactive Geometry Measurement Based on 3D Reconstructive Spatial Data

The technology of geometry measurement for 3D spatial data is widely used in development software for modeling and simulation based on OpenGL. The key technology is how to pick point with mouse in 3D scene which OpenGL doesn´t provide. In this paper, a policy for picking intersection point based on reconstructive isosurface is supposed. The principle of picking spatial point with selection ray is explored. The technologies for the process, such as transformation of screen point to selection ray, building for selection ray equation and triangular facet equation, intersection points for selection ray with triangular facet, filtering and judgment for picking point, are described in detail. Algorithm steps are designed for measuring distance of two points come from reconstructive isosurface with marching cubes based on high speed transient electron beam scalar field.