World Wind Map Tile System

From Wikiteer

The World Wind Map Tile System is a way of serving images from a NASA World Wind image server.

World Wind uses map imagery in the Plate Carree projection (aka geographic projection).

For performance reasons, World Wind stores multiple copies of the same map in successively higher resolutions. Each additional layer quadruples the number of tiles. Thus the tile size, in degrees (LevelTileSizeDegrees), halves with each successive level.

Each tile is a 512x512 pixel square that can be stored in any image format such as PNG, JPG, DDS, etc.

The coordinate system for World Wind starts at the lower left corner.

For an example

The base layer divides the world into 36x36 degree pieces starting at level 0.

level 0 36 degrees 50 tiles (10x5)
level 1 18 degrees 200 tiles (20x10)
level 2 9 degrees 800 tiles (40x20)
level 3 4.5 degrees 3200 tiles (80x40)
level n 36/2^n degrees 50*4^n tiles (Failed to parse (Can't write to or create math temp directory): 10*2^n

xFailed to parse (Can't write to or create math temp directory): 5*2^n )

  • Image:Math01.png
  • Image:Math02.png
  • x=(long+180)/LevelTileSizeDegrees
  • y=(lat+90)/LevelTileSizeDegrees


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