----------------------------------------
> From: g...@ir.bbn.com
> To: rw_nor...@hotmail.com
> CC: viking-devel@lists.sourceforge.net
> Subject: Re: [Viking-devel] Viking Map Generation with Mapnik C++ Library.
> Date: Sun, 1 Feb 2015 11:22:58 -0500
>
>
> Wow, that's very cool.
>
> It would be really nice if the mapnik dependency could somehow be
> additional rather than either/or. From a packaging viewpoint, I'd like
> to see a way to have
>
> base viking
> viking-mapnik
I see your point. I suppose one would write a sufficiently clever configure
script to enable the output of a different binary name (not that I currently
know how to).
However a secondary issue is it would make the help documentation more complex
too - as presumably you'd need an appropriate man page for each binary and also
relevant information in the main online help guide.
So I don't want to do this unless *really* necessary.
> but perhaps what's unwarranted as it's not clear that mapnik is that
> heavy.
I don't believe including Mapnik is that onerous since it is mostly in shared
libraries and the relevant code only initializes if you actually use a Mapnik
layer.
My current viking size is 1.6Mb. (Version 1.5.1 is 1.3Mb)
> Thinking about caching, it would seem that it might make sense to have
> viking fetch tiles from a local mapnik server, but I guess you can
> already do that with the way viking is now, and this is about having it
> generate tiles on the fly without having the server part of the mapnik
> stack set up.
Yes exactly.
> And maybe if there is only one user, caching doesn't really that help
> that much.
>
> How do you find the render speed, and are these tiles cached like the
> ones that are fetched?
Caching does seem to be required - generating map tiles can be slow (slower
than I thought I would be - as initially I wrote the code to just load it into
memory) - but it depends on the complexity of the map data.
OSM-Carto stylesheet - typical rendering of a city 'block' (i.e. a few roads &
buildings) on my 1.4GHz Quad Core Athlon is quick 0.1 seconds per tile or so,
but when viewing the whole city (i.e. hundreds/thousands of roads & buildings)
it can slow down to around 2 seconds per tile (sometimes a random tile takes
over 30 seconds - I don't know why).
So without caching you may not see anything for quite a while when you change
zoom levels or pan around quickly.
Tiles are cached in directory specified in the Mapnik Rendering layer property
(it defaults to ~/.viking-maps/MapnikRendering - so for different stylesheets
it's wise to change this to a specific directory per style) - the cache is
always in the OSM Slippymap layout (zoom/x/y.png)
There is a layer option to off the use of the tile cache.
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