Mkgmap/help/custom
From OpenStreetMap
Contents |
Customising the map
You can completely change which features are displayed and at what zoom levels.
First you need to understand a little about the way that the zoom works in Garmin maps. There are two concepts 'resolution' and 'level'.
Resolution
The first is 'resolution' this is a number between 1 and 24 with 24 being the most detailed resolution and each number less is half as detailed. So for example if a road was 12 units long at resolution 24 it would be only 6 at resolution 23 and just 3 at resolution 22.
On a Legend Cx the resolution corresponds the these scales on the device:
| Resolution | Scale on device |
|---|---|
| 16 | 30km-12km |
| 18 | 8km-3km |
| 20 | 2km-800m |
| 22 | 500m-200m |
| 23 | 300m-80m |
| 24 | 120m-50m |
It may be slightly different on different devices. There is an option to increase or decrease the detail and if you change that from 'Normal' then it will change the values above too.
Level
The next is 'level'. This is a number between 0 and 16 (although perhaps numbers above 10 are not usable), with 0 corresponding to the most detailed view. The map consists of a number of levels starting (usually) with 0. For example 0, 1, 2, 3 and a different amount of detail is added at each level.
The map also contains a table to link the level to the resolution. So you can say that level 0 corresponds to resolution 24.
You can specify this mapping on the command line, for example:
--levels=0:24,1:22,2:20
This means that the map will have three levels. Level 0 in the map will correspond to resolution 24 (the most detailed), level 1 will show at resolution 22 (between scales of 500m and 200m) and so on.
The map features file
Take a look at the map-features.csv file in the resources directory of the mkgmap distribution. It may be easier to edit it in a spreadsheet program.
A typical line may look like this:
point|amenity|grave_yard|0x64|0x03|23
- Column 1 is point, polyline or polygon, depending on whether the feature is a point of interest, a line feature such as a road or an area such as a park.
- Columns 2 and 3 are taken exactly from the key and value columns from the map features page.
- Column 4 is the garmin code that you want to use.
- Column 5 only applies to points and also determines the type of the object. The file garmin_features_list.csv (also in the resources directory) has a list of all the values that I know.
- Column 6 is the minimum resolution at which this feature will appear. So in the example here where the resolution is 23 and we had
--levels='0:24,1:22'
- it would show only at level 0. If instead we had:
--levels='0:24,1:23'
- it would show at both level 0 and level 1.
