[mkgmap-dev] Indexing street belonging to two cities

Mon Oct 24 00:56:44 BST 2022

Hi Gerd,

 > The doc shows that you can have up to three cities, and I've no idea
 > how to decide which numbers belong to which city.

I guess the reasonable solution is to split "CityName" and assign all 
numbers to all cities.

I have tested a bit my map and found that with 2 cities in "numbers" 
statement without house numbers, search index contains left city (first 
in statement) and combined city name (Left at Right) form "CityName" 
statement. Right city is missing.

 > The good thing is that we have a *.mp file and a GMP output. This
 > should help to understand the GMP format.

This is not a true GMP format. This is an old MPC data packed as a GMP. 
I have discovered that it works and implemented conversion MPC->NT in 
GmapTool. Then I explained the idea to Staszek Kozicki and he 
implemented the same in cGPSmapper.

You can convert any img using command line version of GMapTool like this:
	gmt -jxzo ntlike.img source.img

MPC data consist of blocks TRE, RGN, LBL etc. Each block starts with a 
header and then data. Header contains pointers to data.

GMP is similar. It starts with a GMP header, then it contains TRE, RGN, 
LBL, NET, NOD, DEM (sometimes more) headers and then all data. GMP 
header contains pointers to following headers.

It is relatively easy pack old format as GMP. But it is not a real 
thing, since it doesn't use any features of NT maps.

-- 
Best regards,
Andrzej