Garmin Tile Filter
Overview
This setting can be found in ‘Menu-Option-Preferences’, section ‘Garmin Map’, field ‘Tile filter’.
The tile filter can include or exclude particular map tiles 1 from being displayed. This might be necessary especially when the number of tiles exceeds the 4GB address space of 32bit Windows systems 2.
The particular tiles to be included/excluded will be specified by their geographical location which in turn is defined by a bounding box.
- Use ‘Menu-Edit-Copy Special-Copy Coordinates Box’ to select a particular map area and create a bounding box definition.
- Paste that string into the tile filter field.
Warning: The tile filter is an advanced functionality and should be used with special care. One side effect is that active filters can limit the address search results because excluded tiles may contain important search index data.
Filter Syntax
BOX: <box> [,<box>] [,BOX: ...]
<box> -> [NOT] <northwest>,<southeast>
NOT -> The optional keyword excludes the box from map,
otherwise the box will be included explicitly.
<northwest> -> <latitude>, <longitude> (1st corner point of bounding box)
<southeast> -> <latitude>, <longitude> (2nd corner point of bounding box)
<longitude> -> -180..180
<latitude> -> -90..90
The section below contains the precise grammar for the filter expressions in Backus-Naur form (BNF).
<start> ::= <boxblock> <nextboxblock> | E
<boxblock> ::= <boxtypid> ":" <box>
<boxtypid> ::= "BOX"
<nextboxblock> ::= "," <box> <nextboxblock> | "," <boxblock> <nextboxblock> | E
<box> ::= <vertex> "," <vertex> | "NOT " <vertex> "," <vertex>
<vertex> ::= <slat> "," <slon>
<slat> ::= "-" <lat> | "+" <lat> | <lat>
<slon> ::= "-" <lon> | "+" <lon> | <lon>
<lat> ::= "0"* ([1-8]? [0-9] <frac>? | "90" <frac0>?)
<lon> ::= "0"* ( ( "1" [0-7] [0-9] | [0-9] [0-9] | [0-9]) <frac>? | "180" <frac0>?)
<frac> ::= "." [0-9]*
<frac0> ::= "." "0"*
C- and C++ comments (/*…*/ and //) are allowed at any position.
Examples
BOX: 55.04,4.69, 47.29,15.74 //includes Germany
BOX: NOT 55.04,4.69, 47.29,15.74 //excludes Germany
BOX: 55.04,4.69, 47.29,15.74, 48.03,5.73, 45.88,10.71, NOT 52.67,13.20, 52.38,13.67
//more complex: includes Germany and Switzerland but excludes Berlin
Remarks
Generally the complete map will be displayed.
The specified boxes will be processed from left to right, one after another. If the first box is an “include” the filter includes all tiles inside the box and the tiles crossed by the box’ edge before the filter proceeds to the next box. If the first box is an “exclude” the filter starts with the full map, excludes the tiles inside the box (not the ones crossed by the edge) and proceeds to the next rule.
In case the bounding box crosses the date line the filter splits the box into two sections internally.
Tile filter always handles complete tiles. It is not possible to include/exclude partial areas of one tile.