Example Analysis of slice format wgs84 in GIS Development
This article mainly introduces the GIS development of slicing format wgs84 example analysis, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let Xiaobian take you to understand.
Description of EPSG:4326 slice generation algorithm in WGS84 coordinate system:
The coordinate system range of wgs84 is: [- 180 degrees], in degrees. Compared with the coordinate range of web mercator, the conversion process of no coordinates in the middle is consistent. From the comparison of the maximum coordinate range, we can see that there is still a difference between the 0th class of wgs84 slice size and web mercator. The range of wgs84, the length is twice the width, the display result is rectangular, the length and width of web mercator range is consistent, and the display result is square. Wgs84 slicing process: longitude and latitude coordinate pixel slicing
LatLon Pixels Tiles
For the wgs84 image data to be cut, there is no need to convert the coordinates to the pixels of the picture, and then generate the corresponding slice data. Because this range is sufficient, there is no problem of data being trimmed at the north and south poles. For the first-level zoom=0 of wgs84 slices, some also start from zoom=1. The size of each first-level slice is 256-256, and the first-level slice has two (TMS) and one (OpenLayers, MapProxy, etc default resolution for WMTS). According to the wgs84 coordinate range mentioned above, the resolution of the first level is:
ResFact = 180.0 / 256 = 0.703125 (2 slices) resFact = 360.0 / 256 = 1.40625 (1 slice) after each magnification stage, corresponding to the first resolution / 2, these resolution levels are various programs (scheme) that can make slicing software, such as Arcgis Server,Geoserver, etc. Wgs84 slices are applied to three-dimensional maps on a sphere, such as googleearth, etc., and the effect is quite suitable. Thank you for reading this article carefully. I hope the article "sample Analysis of slice format wgs84 in GIS Development" shared by the editor will be helpful to you. At the same time, I also hope you will support us and pay attention to the industry information channel. More related knowledge is waiting for you to learn!
