[josm-dev] Handling large files?
conzar at gmail.com
Tue Nov 25 14:54:35 GMT 2008
All, the description below is information about the project that I'm working
on. I am thinking that these features will be added to the MotoHUD project
I started several years back. (http://sourceforge.net/projects/motohud).
I have been thinking about improving our automobile navigation systems and
have arrived at the idea of developing an automatic governor system. What is
Well an automatic governor is a device that regulates the speed of an
automobile. GPS is vital to this system because the information about the
road and its speed determines the maximum allowed speed for the automobile.
Why would anyone want to use it?
This system guarantees the driver that they will always be going a "safe"
speed and will never get a speeding ticket. This ultimately makes our roads
The interface to the car I think will be the most challenging due to
manufacture specific interfaces to the "computer" which controls the
"accelerator" information. But this interface is trivial to implement once
the connection between the accelerator and the car's computer is defined. A
simple algorithm can be used to prevent the car from exceeding the speed
limit based on the current speed, the max allowed speed, and the input from
The reason I would like to use OSM data is that it provides the "speed
limit" data for the road. It can do this explicitly by setting the maxspeed
tag or via the highway tag (the highway tag provides a default speedlimit
based on the country).
So for this project, displaying the map isn't necessary. "...that you want
to read your coordinates from a gps device and start an action depending
where you are?" Yep, your right!
On Mon, Nov 24, 2008 at 3:42 PM, Frederik Ramm <frederik at remote.org> wrote:
> Michael Speth wrote:
> > So I would like to use DB4O (An object oriented DB that can be embedded).
> You're asking for trouble. Of course you can do that. You can also use
> Hibernate to serialize OSM objects if you so desire. It's just that
> you'll not get anything out of it that can even remotely be called
> "performance". If your main use is doing queries like "on what road is
> the following point", then you absolutely have to have a spatial index.
> I read that there is a DB4O spatial initiative but they haven't produced
> results yet. You can emulate a spatial index by calculating "tiles" or
> "buckets" like it is done in our current MySQL API but it'll be
> considerably more manual work than just writing "db.set(something)".
> > The DataSet dataSet that was returned from the parser can simply be added
> > DB4O by the following call assuming that the db object is already
> > initialized.
> > db.set(dataSet);
> > db.commit();
> > Easy huh?
> Gives you a warm fuzzy feeling but won't give you speedy results.
> > So are you suggesting that JOSM cannot do what I require?
> JOSM is optimized for interactively working on objects (if anything) -
> not for mass querying.
> > If not, then the libosm would have parsers that are similar to JOSM?
> Similar but leaner, with less memory consumption. But even with these
> you'll probably run into trouble. Tell us more about what exactly you
> want to do and we can tell you if it will work.
> Frederik Ramm ## eMail frederik at remote.org ## N49°00'09" E008°23'33"
Michael Speth 石雨濛
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