I noticed that some of my .mp files have
Levels=4
...
Zoom0=1
Zoom1=2
Zoom2=3
Zoom3=4
whereas some others have
Levels=5
...
Zoom0=0
Zoom1=1
Zoom2=2
Zoom3=3
Zoom4=4
The history of those is lost to me so I was trying to understand what the "Zoom#="
parameter does.
Reading the cgpsmapper manual, "Level#=" and the difference between "Hardware" and "Map" zoom levels are thoroughly explained. But all I can find for "Zoom#=" is "Refer to Section 4.4" - yet that section discusses "Level#=" but nowhere mentions "Zoom#="! There is a later use of
Zoom0=0
Zoom1=1
..
Zoom4=4
in an example - but that it all I can find!
I'm surprised that this seems an omission from the otherwise remarkably detailed descriptions in the manual. Does anyone know what "Zoom#=" is supposed to do? Might this be an obsoleted parameter?
Jack
Hi Jack,
The Levels# directive links hardware levels (bits per coordinate like 21 or 23) to zoom levels.
For each object, the Data# directive defines the level at which the objects coordinates apply. My assumption is that the Zoom# directive maps the Data# to the Level#.
For example LevelX=21 ZoomX=Y DataY=(50.1,0.5) .
But, for safety, I keep X and Y the same so it's always, for example Zoom2=2
Since I've been running a bazillion variant runs lately, so now have a relatively quick testing process, I decided to run a test of the "Zoom#=" parameter. My test run compiles two different .mp file using mkgmap to create two separate .IMG files, then again uses mkgmap to combines those files into a gmapsupp file. The first file always had Levels=5 with "Zoom0=0 ... Zoom4=4". The second file always had Levels=4 with 2 cases (A) "Zoom0=0 ... Zoom3=3" and (B) "Zoom0=1 ... Zoom3=4". I could not see any difference whatsoever between the two cases with differing Zoom# parameters.
Jack