A "pyramid" of square tiles. Each level of the pyramid on the way down has four times as many tiles as the previous level.

When SIS draws an Index Overlay with a Pyramid namer, only one level of the pyramid will be drawn. For example, suppose that the bottom level of the pyramid has tiles of 1000m at 1:10000 scale, then the second level of the pyramid will have tiles of 2000m at 1:20000 scale. Now if you zoom in to an effective scale of 1:10000 then SIS will only draw tiles from the bottom level, but when you zoom out to 1:20000 then SIS will only draw tiles from the second level.

The properties of the Pyramid correspond to tiles on its bottom level (e.g. the smallest tiles).

Typical tile name: 0qNNNNNN.ext, where N is between 0 and 3 and specifies a pyramid level quadrant.

namer$ argument to CreateIndexOverlay and CreateIndexCoverage

  • APyramidNamer(bCartesian%,width#,height#,projection$,nDigit%)

    True   The tiles are in a cartesian Coordinate Reference System.
    False   The tiles are in a spherical Coordinate Reference System.

    width#, height#
    The width and height of each tile, in metres or degrees for cartesian and spherical tiles respectively.

    A named Coordinate Reference System stored in a Named Object Library (without quote characters).

    The maximum number of digits in a file name, in the range 1 to 24 inclusive. This value also controls the depth of the pyramid.



  • Cartesian tiles: _bCartesian&
    Are the tiles in a cartesian coordinate reference system?

  • Number of digits in tile name: _nDigit&
    The number of digits in the tile name.

  • Projection: _projection$
    The tile naming convention Coordinate Reference System.

  • Scale: _scale#
    The tile scale.

  • Tile height (degrees): _degree_height#
    The tile height, in degrees.

  • Tile height (metres): _metre_height#
    The tile height, in metres.

  • Tile span: _span#
    The tile span, in metres.

  • Tile width (degrees): _degree_width#
    The tile width, in degrees.

  • Tile width (metres): _metre_width#
    The tile width, in metres.