[Tagging] Micro Mapping, was Race track

John Smith deltafoxtrot256 at gmail.com
Mon Feb 1 05:26:34 GMT 2010


On 1 February 2010 14:21, Roy Wallace <waldo000000 at gmail.com> wrote:
> 1) use tags on nodes to describe an area
> 2) use an area to describe an area
>
> Generally speaking, I predict 2) will be easier.

Just like ways there is a lot of meta information to describe lanes,
can you change lanes, do lanes have different speed limits, sure areas
could be used for this, but the down side is you still need a way to
describe the legal direction of travel, so the problem still exists an
area alone doesn't describe everything.

> Erm no. You need to know along which direction the width is measured.

A node is a point, the direction of width would be 90 degrees to the
direction of travel.

> You could *assume* that this is in the direction that bisects the
> angle between the previous and following nodes, but 1) this is an
> approximation and 2) this doesn't work if the node is connected to

Even areas are approximations, go look at river banks and tell me how
many points are needed for an area, infinite is the correct answer
anything less is an approximation.

> more than 2 other nodes. Thus... nodes are hardly the "perfect point"
> to indicate width.

Neither are areas, they might approximate better but they still won't
indicate width perfectly and they don't indicate direction of travel
so we're still at square one, that is trying to describe a road, and
the sub-objects, that is lanes etc.

So the question still remains, how to describe a road way more
accurately with a single object.




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