GeognoSIS Tile Service

A GeognoSIS Tile Service is a Cadcorp Tile Cache served by GeognoSIS.

When map tiles are loaded initially, they are cached and stored in the TileCache folder of the GeognoSIS installation folder.

Tiles from this cache are served to all new users to save time and bandwidth.

Select GeognoSIS Tile Service in the Layer Type drop-down box and give the overlay an appropriate name.

Field	Is it Optional or Required?	Description
Name	Required	Display name for the layer.
Visible	Required	Check this tickbox to turn the layer visible.
URL	Required	The URL connection to the Cadcorp GeognoSIS instance e.g.,http://server.domain:4326/tileservice/tile.exe
Copyright Text	Optional	Text entered here will appear across the bottom left of your Cadcorp SIS WebMap site.
Layer	Required	The Layer you wish to add from the Tile Service.
Is Base Layer	Required	Designate this as a Base Layer.
Include in Layer Tree	Optional	Allows you to switch between base layers in the Map Features dialog. (Only for desktop versions)
EPSG Code	Required	The EPSG code the tile cache was created in.
Image Format	Required	Image format the tile cache was created in.
Factor	Required	The multiplier value applied to the initial value to define the levels, according to the increment value.
Increment	Required	Combined with the factor and the initial size defines the levels.
Initial Size	Required	Helps define the highest resolution. This value is in CRS units (i.e. for OSGB it is metres and for WGS84 it is degrees).
Origin X	Required	The x coordinate of the origin (as defined when the tile cache was built).
Origin Y	Required	The y coordinate of the origin (as defined when the tile cache was built).
Tile Width	Required	The width of the tiles to be displayed (as defined when the cache was built).
Tile Height	Required	The height of the tiles to be displayed (as defined when the cache was built).
Transition Effect	Required	This is set by default to Resize. This means when zooming into a map, the cached tile is resized and displayed immediately for user-friendliness. The actual tile is then drawn on top of the resized one as it becomes available.
Buffer	Required	Number of extra tiles to load around the map that is displayed on the screen. Having a buffer makes panning smoother but a large buffer will result in a slower map render as it will take longer for all the tile requests to be returned by GeognoSIS.

A note on Initial Size, Increment and Factor

The initial size defines the resolution the data uses at level 0.

In the example below it is 1m. Larger values can be selected for the initial size but this will reduce the highest resolution available.

The resolution of subsequent levels is determined by the factor and increment. For every increment increase the resolution is multiplied by the factor.