Patent ID: 9135507
Filing Date: 2015-09-15
Classification: G06K,G06T

Abstract:
1. A method for searching a building roof facet and reconstructing a building roof structure line from a plurality of building roof facets, comprising the steps of: (a) composing each of the plurality of building roof facets by lidar point clouds, respectively, and picking up at least an optimal roof facet by using a progressive roof facet searching process; the step (a) further comprises the steps of: (a1) composing a triangle net pattern by using the lidar point clouds, filtering out point clouds on wall facet by using a normal vector of the triangle net pattern, and filtering out point clouds on ground facet by using a normalized altitude of the lidar point clouds, to obtain a set of roof point clouds; (a2) composing a relatively stable local facet by using a point group fashion process; (a3) determining a normal vector between local facets by using an region growing process, to compose assumptive roof facets; (a4) filtering out a non-roof facet from the assumptive roof facets by using four non-roof facet features; (a5) differentiating roughly each of the roof facets into a pitched roof and a possible flat roof based on a pitched extent of each of the roof facets; and (b) projecting the roof facets onto a 2-dimensional space and determining an intersection stage of the roof facet by using of morphology, to determine an area of the roof structure line, establishing an initial boundary line, establishing each of structure lines by considering aerial imagery to generate a roof structure line in a 3-dimensional space, and enhancing an accuracy of the roof structure line by using the lidar point clouds.