[Routing] monav, Mapnike render generates huge and fixed-sized index file.

[feverzsj]

hi,

VeaaC FDIRCT wrote:
> If you do not have set the "render the whole world down to level x"
> setting to 13, there might be a problem with the bounding box
> specified in your OpenStreetMap data set. If this is the case, would
> you provide me with the header of your .osm file to check it? Maybe
> MoNav misinterprets the bounding box.
>   
Ah, yes, that should be the problem. After checking the osm file, I 
found the bounds element was set to a wrong area for unknown reason. 
Setting the bounds manually, the preprocessor successfully generated the 
tiles with small index file.
It may be better to let the osm importer recompute the actual bound 
while importing, or let user set one, since the dataset used to render 
could be much larger than the dataset used to route and user may want 
some larger bound to be rendered.


> I might implement that, but the benefits are not that great. Rendering
> all zoom levels takes only half of the storage space of the deepest
> level, e.g., Germany, zoom level 15 3,2GB, zoom level 1-14 1,8GB -
> 56%. Restricting yourself to the two deepest levels takes about 4.4GB,
> about 88% of the overall size.
>   
I'd consider some 20%~30% cut down is also helpful. For example, skip 
all the odd zoom levels.
The zoom settings in client should then remap to the selected zoom 
levels and remove the others correctly.
Browsing less zooms also ease the use of small local maps on mobiles.


  --Regards, zsj