MODLAND Tile Calculator Notes

1. The center of the pixel in the upper left corner of a tile has the coordinates (0.0, 0.0).
2. Tiles are numbered starting with zero in the upper left corner. There are 36 horizontal tiles and 18 vertical tiles in the Integerized Sinusoidal, Goodes Homolosine and Sinusoidal grids. There are 9 horizontal and vertical tiles in the Lambert Azimuthal Equal Area grids.
3. Be careful around the edges of each horizontal row in a tile in the Integerized Sinusoidal grid. Because of the way the tiles are aligned, a small change in the latitude can cause a shift of up to a pixel in longitude.
4. This program now maps pixels in all of the nested and unnested Integerized Sinusoidal Grids (1 km, 0.5 km and 0.25 km).
5. Except for Goodes Homolosine, the grid and pixel sizes are not exact multiples of 1 km, they are only approximations. For instance, the grid and pixel size for the 1 km Integerized Sinusoidal grid is exactly 926.62543305 m.
6. The current defaults for the Collection Versions 1 and 3 MODLAND fine resolution grids are the 0.25 km Integerized Sinusoidal Grid. This grid should be used for all pixel sizes: 0.25, 0.5 and 1.0 km.
7. The Sinusoidal grid is used for the Collection Version 4 and higher MODLAND fine resolution products.
8. This program now maps pixels to the global map coordinates, in addition to tile coordinates (3/26/01 update).
9. This program now maps pixels to the Sinusoidal grid coordinates (10/24/02 update).
10. Before August 11, 2000 this program had a bug that caused the vertical coordinates to be one too large. For instance, instead of returning 103.0 for the line value, the program would incorrectly return 104.0. If this occurred on the edge of a tile, the vertical tile number would also be calculated incorrectly.
11. The source code for the tile calculator (tilemap3_r4_0.tar) is now available. This software is provided with minimal support.

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