Le 12/03/2018 à 17:58, Bald Eagle a écrit :
> 
> As a natural and plentiful supply of Dried Frog Pills (TM) is becoming more
> scarce and illicit as the decades whiz by, errant thoughts on various subjects
> and POV-Ray such as the following continually fill my mind:
> 
> The lettering on road surfaces is a vertically stretched typeface, to compensate
> for the somewhat extreme viewing angle from the driver's seat.
> 
> I have not seen any specifications for these letters and arrows, and have not
> yet found a source to download such a font / typeface.
> 
> Doing a bit of trigonometric scribbling, at first glance it appears that the
> upper half and lower half of such a typeface [ideally] ought to be scaled to
> different extents.
> 
> So my questions are:
> a) can anyone dig up DOT specs?
> b) Are such fonts available for download?
> c) What's the best way to display a text{} object such that the bottom half and
> top half are unequally scaled?
> (I'm thinking CSG-type cropping, or something like Dave Blandston's excellent
> work with text)
> 
> I'll likely work up some diagrams and equations, but I figured I'd just throw
> this out there for fun.
> 
> 

The diagram, I can attach to this message.

For Povray, either
* you compute the shear matrix to project the red box on to the road.
* or you use a 2D pattern in plane of the red box directly on the road
(and let the software do the work)

As a lane is about 3m (maximal width of normal vehicle is about 2m55 in
Europe, check your local law for your limitation), that's only 1m & 2m
from the driver's eye on left & right, it might not be worth to
compensate for the horizontal distortion.

I might be a bit short on the base distance: maybe it's a bit more than
5m (5m = another car)

About the font itself, it might be tied to the technology used to paint
the text on the road: it is often made of thick bands, leading to a
box-based police (no round part, straight lines everywhere). But
trunk-printing (like 3D-printing) also exist and can allow more round
police.

Upper case is often preferred.

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