The direction relationship between spatial entities is an important content of spatial relations, and is the basis of more knowledge mining based on spatial data. In this paper, a vector spatial data direction relationship expression model based on azimuth is proposed. When the reference object and the source object are point spatial entities, line spatial entities and area spatial entities respectively, the direction relationship expression model is established. According to the need of natural cognitive language, the quantitative expression model and qualitative expression are transformed. We designed typical sample data, calculated each case in the model, and the results prove the feasibility of the model finally.
KEYWORDS: Point clouds, Buildings, LIDAR, Data modeling, 3D image processing, Visualization, Roads, Detection and tracking algorithms, Video, Remote sensing
The algorithm of extracting skylines are mostly two-dimensional image processing methods, which are lack of geographic information in current. This paper, a skyline extraction algorithm based on airborne LiDAR point cloud data is proposed. Through the optimization of the EDL algorithm, the shading function is calculated using the projected depth data and applied to color scene images to synthesize a more three-dimensional and realistic point cloud. Through the application in the laser scanning project of Wuhan city, the skyline of key urban areas was extracted and made into a thematic atlas. The results showed that the algorithm can quickly extract the skyline, and the quality of the results meets the requirements.
In view of the fact that the source and target parts are contained in the reference target, the existing model expression is inconsistent with the actual cognition. A quantitative detail direction relationship expression model is proposed to establish a two-layer grid direction relationship matrix for spatial objects. The expression ability of the two-layer grid direction relation matrix is tested and analysed. Through the comparison and analysis with the calculation results of the direction relation binary in literature [7] and the grid direction relation matrix in literature [8], the recognition ability of the two-layer grid direction relation matrix to displacement and rotation is verified. Finally, it is proved that the method in this paper is effective in the calculation of spatial direction similarity, extended cartographic comprehensive evaluation, data matching and fusion applicability of work tasks such as change detection and update.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.