# Pyramid

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%)
**bCartesian%**`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.**projection$**

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

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.

## Properties

- Cartesian tiles

- Number of digits in tile name

- Projection

- Scale

- Tile height (degrees)

- Tile height (metres)

- Tile span

- Tile width (degrees)

- Tile width (metres)

## Properties

**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.