Vector data |
SuperMap 3D supports loading and displaying SuperMap vector (point, line, region, or text) datasets in a 3D scene. The essence is that it places the 2D vector geometries on the sphere according to their coordinates. When loading 2D vector data in a 3D scene, 2D data are converted to 3D layer data. It means that the spatial information of every geometric object adds an additional Z coordinates. And now you can stretch the vector geometries with a hight you set. And you also can set a elevation, a display style for them.
The vector datasets supported in 3D scene are: point, line, region, route, network and the geometry objects (point, line and region) in compound datasets.
Vector 3D caches mean the 3D caches generated from vector dataset. The purpose is that, when users view a map or a scene at some scale, the cached images will be automatically loaded for display to ensure the smoothness of the viewing. And unlike the generation of other types of cache data, the vector 3D caches only generate caches at one specific data, which means it creates only one level caches, because vector data themselves are not affected by resolution, the zooming in/out operations can not affect the display clarity.
After cache is generated from vector data, a cache configuration file *.scv and a cache index file *.dat are generated. The *.scv file is in a plain-code format, and is generated by default when vector cache is generated by the SuperMap desktop product. Cache data can be loaded through this configuration file. This file records the cache version information, the network path and local path of the cache, the cache name, the cache file type, the extent for generating the cache, the longitude and latitude range of the tile on the first level, and the extent for displaying the data at one time.
SuperMap 3D service adopts the following methods to improve the effiency:
During the process of converting 2D vector data to 3D data, a third-dimension coordinate (the elevation value z) is added. Thus the data volume is significantly increased. Directly transmitting 2D vector data can effectively reduce the data volume without affecting the data quality.