| 摘要 |
PROBLEM TO BE SOLVED: To specify a gravity direction by analyzing a three-dimensional point group expressing a contour of a feature.SOLUTION: Three-dimensional point group data in which position coordinates expressing contours of a plurality of features in a three-dimensional coordinate space set for analysis and normal vectors on a surface on which existence of points is estimated are prepared. First, a temporary gravity direction is determined by performing main component analysis for the three-dimensional point group data and a side face point group is extracted by excluding points having normal vectors along the temporary gravity direction. Then, point groups are separated in each building unit by grouping points with near inter-point distances to determine side faces of each building. Normal vectors are found out by the main component analysis of respective obtained side faces and a gravity direction is found out by finding a weighted average of outer products of the normal vectors. Thus, the gravity direction can be accurately determined by using three-dimensional point groups expressing a plurality of features in a wide range and using a statistical procedure to be the main component analysis. |
