Thread: Navit GPS (and libgarmin) for os2008
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dwould is offline dwould
2009-01-29 , 12:58
Posts: 529 | Thanked: 262 times | Joined on Dec 2008 @ Eastleigh, Hampshire, UK
#165
Re performance, my guess (and it was sort of mentioned on #navit) is that reducing the number of tags you are looking to display is a good thing to do. E.g. if you are not interested in showing Stop signs on your map, then remove that item from navit.xml. These things all take time to find and render.
As a test of how busy Navit can be, set debug navit to level 1 or 2. Then send the output to a file using 2> log.file. This will likely show 80000 plus lines of output by the time the map displays, much of it Attr searches. So the advice above would seem to bear out the benefits of reducing your conf file. Other than that it will take using a tool such as Valgrind to determine code hotspots. Perhaps reducing the rate of GPS updates will help, I am just guessing on that though.
I've tried removing a lot of the POI's that I'm not interested in. and it doesn't make a particularly notable impact on performance. My main issue is that actually whilst driving it can get quite laggy from your actual position (particularly if you drive off the planned route and it has to recalculate)
I was wondering if there are any optimizations to be had in tuning what gets rendered. I don't know how the logic figures out what it is rendering or how much to do, but if you could for instance say only render my route plus roads at most 2 removed from my route. that might help. eg less detail but just what you need.
Also I have no idea how the rendering is done, is it possible there are faster alternatives?
Basically I feel that the n810 should have enough grunt to do a smooth job, but it does not. I'm hoping that's a question of programming rather than hardware limitation.