I have found a lot of information on the Internet and have never understood it. Today I finally learned it myself. I 'd like to share it with you.
(1) plane coordinate system
Resolution, ground resolution, similar to spatial
Resolution (spatial resolution). Here we mainly focus on the form of pixel size: the ground size (meters) represented by a pixel ). Take the day map as an example. If the level is 1, the image size is 256*256 (4 tile), and the resolution of the equator space is: the equator perimeter/512. The spatial resolution of other latitudes is the latitude circle length/512, and the extreme Arctic is 0. When the level is 2, the spatial resolution of the equator is the circumference of the equator/1024, And the other latitudes are the latitude circle length divided by 1024. Obviously, ground
The resolution depends on two parameters: Zoom level and latitude. level determines the number of pixels and latitude determines the distance between the ground.
Take level 1 as the premise, take the screen resolution as 96 DPI (pixel/inch)
Ground Resolution: One pixel represents the distance (meters) of the ground, measured in pixels/meters;
Resolution = actual distance/number of pixels on the screen
= Actual distance (meters)/512 (pixels)
Scale: The distance on the screen represents the distance of the ground, no unit, only a value
Scale = 512 (pixels)/screen resolution (pixels/inches) * 0.0254 (meters/inches)/Actual distance (meters)
Operation: the screen resolution of a map is 96 (pixels/inch)
Resolution * scale = 1/96*0.0254 = 0.0254/96
Scale = 0.0254/(96 * Resolution)
Scale = 1: (96 * Resolution/0.0254)
(2) longitude and latitude
The latitude and longitude are similar to the plane. However, because the latitude and longitude are measured in degrees, you need to change the degrees to meters during conversion. The conversion company is as follows:
Scale = 1: (96*2 * Math. Pi * 6378137 * Resolution/360
/0.0254 );
