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.

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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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Attachments:
Download 'road.png' (59 KB)

Preview of image 'road.png'

Le_Forgeron <jgr### [at] freefr> wrote:
> Le 12/03/2018 à 17:58, Bald Eagle a écrit :

> For Povray, either
> * you compute the shear matrix to project the red box on to the road.

I'll have to think about that a bit, but I believe I could work that out - I
hadn't thought about shearing a text object.  Nice suggestion  :)

> * or you use a 2D pattern in plane of the red box directly on the road
> (and let the software do the work)

Ah yes, having recently played with labeling the values of the crackle pattern,
I should have thought of applying that same technique.
A "2D" pattern that stretches infinitely "deep" should intersect the plane of
the road and give approximately the desired effect.

> ... it might not be worth to
> compensate for the horizontal distortion.

Probably not.

I have actually seen a fair number of rounded and lowercase letters, as well as
stuff like pedestrian and wheelchair glyphs.


Though I'll have to crunch some numbers to see what the actual difference in
scaling between the top and bottom is.  I made essentially the same diagram that
you did, with the same red plane perpendicular to the camera_location-to-look_at
vector, so I could see what sort of right triangles I'd be working with.
Comparing the projection of the top section with the projection of the bottom
section is what suggested that the difference in scaling might be significant.

Then I had to get back to work in RL...   :|

I suppose if I actually _projected_ the text onto the pavement, or at least
declared such an object that I could then use as an image map...
I'll have to look back over Kenneth's work on the cubic pattern...

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Am 12.03.2018 um 17:58 schrieb Bald Eagle:

> I have not seen any specifications for these letters and arrows, and have not
> yet found a source to download such a font / typeface.

I guess different countries will have different standards (if any) for
such purposes.

According to Wikipedia, pictograms, numbers and texts on German roads
must match regular traffic signs (*), except that they are to be scaled
"vertically" by a factor of 3.

(* Slight variations occur in practice, to allow for application via
stencils.)

> 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.

As far as I can tell, that's usually not done.

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clipka <ano### [at] anonymousorg> wrote:

> As far as I can tell, that's usually not done.

I guess not - for some reason I thought I had seen lettering that was more
properly anamorphic than what is actually used for pavement marking.

I think it's the A, 4, and to some extent the Y and certain arrows that may have
given me that impression.

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In case anyone needs such a thing for scenes:

http://www.cbrd.co.uk/fonts

http://www.mutcd.org/en/products/fhwa/fhwa_symb_en.html

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clipka <ano### [at] anonymousorg> wrote:
> Am 12.03.2018 um 17:58 schrieb Bald Eagle:
>
> > I have not seen any specifications for these letters and arrows, and have not
> > yet found a source to download such a font / typeface.
>
> I guess different countries will have different standards (if any) for
> such purposes.
>
> According to Wikipedia, pictograms, numbers and texts on German roads
> must match regular traffic signs (*), except that they are to be scaled
> "vertically" by a factor of 3.
>
> (* Slight variations occur in practice, to allow for application via
> stencils.)
>
> > 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.
>
> As far as I can tell, that's usually not done.

And probably for good reason.
Trying this out with projected_through lights the effect can appear great for a
non-parallel light source and camera placed at same location. It goes badly when
realizing it won't fulfill every situation, and worse because the road surface
text and symbols need so much space to accommodate them if done as a projection.

Check this out, if you don't mind the basic scene file inaccuracies. I literally
threw it together.

// BEGIN SCENE FILE
#version 3.7;

global_settings {
 assumed_gamma 1
 ambient_light 0
}

// parallel typical method of painting road surface text & symbols
#declare Parallel=no; // otherwise singular projected views
// projected viewpoint won't be seen good from other views

#declare OverheadView=no; // from above to see distortion
// a projected view text or symbol would require much more paint area

camera {
 location #if (OverheadView) <0,30,5> #else <0,3,-15> #end
 look_at #if (OverheadView) <0,0,5> #else <0,0,0> #end
 angle 30
}

#declare Text=
text {
 ttf "arialbd"
 //"IIIIIIIIII" // crosswalk
 "STOP"
 0.1, 0
 translate <-1.33,0,0>
}

light_source {
 <0,3,-15>,
 color rgb 1
  projected_through { object { Text } }
  #if (Parallel) parallel point_at 0 #end
  translate <-3,0,0>
}

#declare StraightArrowSymbol=
union {
 box {
  -0.5,0.5
  scale <0.25,0.75,0.01>
 }
 box {
  -0.5,0.5
  rotate z*45
  clipped_by {
   plane {
    -y, 0
   }
  }
  scale <0.325,0.5,0.01>
  translate y*0.375
 }
 translate <0,0.5,0>
}

light_source {
 <0,3,-15>,
 color rgb 1
  projected_through { object { StraightArrowSymbol } }
  #if (Parallel) parallel point_at 0 #end
  translate <0,0,0>
}

#declare RightTurnSymbol=
union {
 box {
  -0.5,0.5
  scale <0.25,0.5,0.01>
 }
 torus {
  2,1
  rotate x*90
  clipped_by {
   box {
    0,3
   }
  }
  scale <-0.125,0.125,0.01>
  translate <0.25,0.25,0>
 }
 box {
  -0.5,0.5
  rotate z*45
  clipped_by {
   plane {
    -y, 0
   }
  }
  scale <0.325,0.5,0.01>
  rotate -z*90
  translate <0.25,0.5,0>
 }
 translate <0,0.5,0>
}

light_source {
 <0,3,-15>,
 color rgb 1
  projected_through { object { RightTurnSymbol } }
  #if (Parallel) parallel point_at 0 #end
  translate <3,0,0>
}

plane {
 y, 0
 pigment {
  color rgb 1
 }
 finish {
  diffuse 2
 }
}

// grid
union {
#for (I,-10,10,1)
cylinder {
 -x*10,x*10,0.02
 pigment {
  color blue 1
 }
 finish {
  emission 1 diffuse 0
 }
 translate z*I
}
cylinder {
 -z*10,z*10,0.02
 pigment {
  color green 1
 }
 finish {
  emission 1 diffuse 0
 }
 translate x*I
}
#end
no_shadow
}
// END SCENE FILE

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"Bald Eagle" <cre### [at] netscapenet> wrote:
> In case anyone needs such a thing for scenes:
>
> http://www.cbrd.co.uk/fonts
>
> http://www.mutcd.org/en/products/fhwa/fhwa_symb_en.html

Thanks for the links!

Guess it should be no surprise someone made fonts for "pavement markings". That
term was eluding me before so I didn't find much from quick 'net search.

Now I've seen enough to realize each State here in the US probably has some
individualization regarding those, but maybe mostly adopted from a universally
accepted idea to begin with. Namely a simple vertical (or length) stretched
method. Although I didn't actually find a real answer to that question.

I came across a PDF about Florida and a road planning software, and Michigan has
a PDF telling about it's "research" into such things too.

You helped get rid of my Monday night boredom! Temporarily anyhow. ;-)

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"Bald Eagle" <cre### [at] netscapenet> wrote:

>
> The lettering on road surfaces is a vertically stretched typeface, to compensate
> for the somewhat extreme viewing angle from the driver's seat.
>
Funny thing about such road-painted signs:

Take this for instance...

         STOP
          ON
         RED

That's how it looks from the driver's location (or better yet, from a bird's eye
view above the driver.) And that's how we're expected to read it.

But on a dark rainy night, those big stretched-out words appear differently. The
first word *I* see in the headlights is... RED.
Then ON.
Then STOP.

Depending on the actual message, that can be... confusing!  So while I'm
attempting to make sense of it-- thinking, "red on stop? what does *that
mean*?"-- I mistakenly go through the read light, get broad-sided by a large
truck, then wake up in hospital months later-- my very first thought being,
"Hey, did I read that message the right way??"  :-P

The logic of civil engineering sometimes escapes me...

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Am 13.03.2018 um 20:47 schrieb Kenneth:

> Take this for instance...
> 
>          STOP
>           ON
>          RED

I hear you.

Fortunately, over here in Germany we rarely ever have this problem:
Virtually all our traffic signs and corresponding road markings are
purely pictographical; and when we do have text on road surfaces, it's
usually just a single word, such as "TAXI" or "BUS" to indicate a lane
reserved for particular typs of vehicles.

One of the things I found most annoying when driving a car in the US was
that I was ever so often forced to _read_ while driving. Felt pretty
distracting to me.

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