Re: [Flightgear-devel] Yet more aerodrome taxiways/aprons questions

[Curtis O. <cur...@gm...>]

On Thu, Jul 17, 2008 at 2:55 PM, Ralf Gerlich wrote:

> Hi Curt!
>
> Curtis Olson wrote:
> OK, maybe I misread the code. Wouldn't lines 216-236 in rwy_visual.cxx
> generate a small threshold marking? Would that be 14ft in length (from
> 14/length)?


That is only the thick painted line marking the leading edge of the runway I
believe.  The actual large threshold marking bars would be omitted.

I haven't checked this on any specific airport, but I looked into the
> code due to Martin's question (top of this thread) about the markings
> included in the "Visual" marking type.


Looking at Martin's question, based on what his runway includes, I would
have said use non-precision markings.  But then later he says that
non-precision marking are not appropriate?  Perhaps he could elaborate on
that last point a bit?

I should take a step back here and point out that the runway marking scheme
is not designed to be able to handle every possible combination of marks
that people might paint on their runways.  There are FAA standards for the
USA, and it appears that much of the world does something similar,
especially for larger airports, but for other smaller airports, who knows?
Some real person has to go out and paint the lines and they might not follow
the FAA AC exactly as it is written.  What we have is a comprimise ... a way
to represent a huge proportion of the worlds runway markings using a
relatively small number of embedded textures (rather than struggling with
polygon overlays.)

Hope that helps,

Curt.
-- 
Curtis Olson: http://baron.flightgear.org/~curt/