Thread: Map Priorities and Layering.

Originally Posted by Schermann

So, can one edit the priority to suit oneself?

See Neil answer but be ready that it is give effect not for all maps. Try on in any case...

Originally Posted by Kanopus

Garmin can display multiple map at once. What you will see, which map will be on top, depends on 2 main factors:

- type of the map
- internal map priority and transparency settings

There is a list indicating priority according to map typ, from the top to bottom:

1. City Navigator
2. City Select
3. MetroGuide
4. BlueChart
5. Fishing Hotspots
6. Water Waypoints and Lights
7. Road & Recreation
8. Topo
9. WorldMap

I'm not sure how precise is this list, but i can confirm, that type of the map is important.

Second factor is draw priority. It is a number in range 0-31 hidden inside img. This value can be edited by some tools. Map with bigger priority are displayed over other maps.

Map can have transparency attribute. It makes map polygons invisible. Transparent maps are displayed over non-transparent maps.

Both factors are used by GPS when drawing maps, but i really don't know, how exactly draw order is calculated. Draw priority is a simple number, changing it gives expect effect, but it is difficult to tell, how map type is converted or compared to priority numbers.

Ok, I have IMGTool tool and so here goes for finding out map priorities.

The Etrex 20 does not show Bluechart and City Navigator at the same time but Topo and Blue chart are fine together!

--------- So here is my general map priorities I found, so why can't CN and Blue chart live together on eTrex? ----------------


***********************************************************

PRIORITY = >>##
Transparency = YES/NO

• gmapbmap >> 0 / no
  
• gmaptz >> 0 / no
  

• OSM >> 20 / no
  
• TOPO >> 20 / no
  

• Contours >> 25 / yes
  
• Shonky-Maps >> 25 / yes
  
• Tracks - 4 - Australia >> 25 / yes
  

• Golf >> 28 / no
  
• BlueChart g2 >> 28 / yes
  

• CN >> 30 / no
  
• CX >> 30 / no

***********************************************************

So to make CN/CX to work with Bluechart do I change the map priority of Bluechart G2 to 31?

Here goes... IT WORKS!!!

I made CN = 30, Bluechart = 31, Contours = 31... both showing together again




... all happy!

Don't be a dope like me and go changing transparencies without checking inside the file what is and is not transparent...

Screwed up most of my maps and had to reload them afresh in virgin unchanged format, LOL!

Using IMGTool I was able to (finally) see the individual settings before messing around with them.

The pic below shows the non transparent parts of the file [important]!




Hence look before you leap... and always keep a virgin backup copy!