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Preface:
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- navigation LWDB files contains a number of speed limit datasets
- two different datasets are known
-> speed camera datasets
-> speed limit datasets to be used to display limits on motorways
- contents of a dataset are position, direction, speed and control data
- LWDB files including limits on motorways may contain a further
block of datasets -> the end position of a speed limited section


Example:
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- Extract speed limits from "NT_Q2_07_EU_001.lwd" to current folder
navlwdb_tool.exe -vx D:\data\navi-cf_v4.0_image\NT_Q2_07_EU_001.lwd
- Create database from extracted data above
navlwdb_tool.exe -vc NT_Q2_07_EU_001.lwd_contents\metafile_lwdb.txt


Contents of CSV output:
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Area level, Area type:
- speed limit data is divided into rectangular areas
- root area (level 0) is splitted into four rectangular parts (level 1 areas)
- each part (nw/ne/sw/se) may contain limits or further parts (level 2 areas)
- further splitting depends on number of speed limits (not yet investigated)

Latitude, Longitude:
- speed limit position (or end position of limited section)
- coordinate conversion to meters (to compare with covered area)
xLimit = Longitude*72000
yLimit = Latitude/9*1000000

Direction:
- northerly direction in degrees, counting clockwise
- range from 0 to 360, with a resolution of 3 degree
- special value of -1 -> any direction

Limit flag:
- describes the type of dataset
0 -> speed limit dataset (only supported on motorways)
1 -> speed camera dataset

Speed:
- speed limit value
- range from 10 to 150, needs to be a multiple of 10
- special value of 0 -> dynamic speed limit

Limit mode:
- controls behavior of speed limit display
- range from 0 to 15, meaning depends also on limit flag
0 -> regular speed limit
1 -> speed limit depends on the weather or time of day
4..15 -> length of limited section, (value-1)*100m

Area x, Area y, Area width, Area height:
- only informative data, not necessary for composition
- covered area, origin and dimension in meters
- x grows from Greenwich meridian to east
- y grows from equator to north
- restrictions for speed limit position with respect to covered area
x <= xLimit < x+width
y <= yLimit < y+height


Credits:
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- to Mira308sw for investigation of LWDB encoding

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