[Tagging] Should 'highway=incline[_steep]' be discouraged?

Steve Bennett stevagewp at gmail.com
Tue Dec 29 13:07:50 GMT 2009


On Tue, Dec 29, 2009 at 9:01 PM, Liz <edodd at billiau.net> wrote:

> On Tue, 29 Dec 2009, Roy Wallace wrote:
> > An incline is more or less a gradient. From Wikipedia: "The gradient
> > of H at a point is a vector pointing in the direction of the steepest
> > slope or grade at that point." A point can have a gradient, and thus
> > an incline.
> you'd better read better than that
>
> the vector has a gradient (in fact it is compulsory)
> the point can not
>
>
A point in space doesn't have an incline, or a direction, or anything. It's
just a point. A location in space.
But a point *on a surface* does; it's not just a point, but a very small
part of a greater object. It's that surface which gives the point meaning.
In particular, the "direction" of the point is the surface normal. Now, to
describe the "incline" of the point, you need to know in which direction
you're talking. Placing the point on a line reduces the possibilities down
to  two directions, and if the line is directed (like a way in OSM), then
theoretically you have nailed it down to one direction, so it's meaningful.

I don't think "an incline is more or less a gradient", from that definition.
At a given point on the side of a hill, we would happily say that one road
has no incline, if it's running flat along the edge of the hill, while
another has a steep incline up or down, even though it passes through the
same point...

Steve
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