TITLE: The Forth Bridge
NAME: Christian Radek, Ph.D.
COUNTRY: Germany
EMAIL: christian.radek@dortmund.netsurf.de
WEBPAGE: http://home.netsurf.de/christian.radek/
TOPIC: Landmarks
COPYRIGHT: I SUBMIT TO THE STANDARD RAYTRACING COMPETITION COPYRIGHT.
JPGFILE: cr_forth.jpg
ZIPFILE: cr_forth.zip
RENDERER USED: 
    Povray 3.1e.watcom.win32

TOOLS USED: 
    none

RENDER TIME: 
    58' 42"

HARDWARE USED: 
    AMD K6-II 300MHz 64MB

IMAGE DESCRIPTION: 

The image depicts the rail bridge across the Firth of Forth (Scotland),
commonly known as 'The Forth Bridge'. The Forth Bridge can be
viewed as a landmark in Scotland but also as a landmark in engineering -
i.e. in the transition from cast iron bridges to steel bridges. 

The Forth Bridge was constructed between 1882 and 1890. The zip file
contains three small images which show different stages of construction.
If one considers the tools available at that period of time, building
the bridge was a great achievement.

Here are some figures:
Total length of the bridge including both approach viaducts  8,296 ft
Length without viaducts ...................................  5,330 ft
Two main spans ............................................  1,170 ft each
Length of cantilever ......................................    680 ft
Maximum height ............................................    343 ft 
Clear height for shipping .................................    150 ft
Weight .................................................... 50,958 tons
Total number of rivets .................................... 7 million           
                                           
Maximum number of people employed in 1888 .................  4,600
Deaths ....................................................     57              
                                        

At the time of completion the Forth Bridge was the largest girder
type bridge in the world until the completion of the Quebec Bridge
in 1917. 

The barrel in the image is a reminder that the bridge has to be
painted every 4 years, a task which lasts 4 years.

Literature:
Firth of Forth and Firth of Tay - Two Railway Bridges of an Era
Arnold Koerte, Birkhaeuser Verlag Basel Boston Berlin 1992
ISBN 3-7643-2444-9 (Basel...) ISBN 0-8176-2444-9 (Boston)

100Yrs of the Forth Bridge
Roland Paxton, Thomas Telford Limited London 1990
ISBN 0-7277-1600-X

The Forth Bridge - A Picture History
Sheila Mackay, HMSO 1993
ISBN 0-1149-5183-7


DESCRIPTION OF HOW THIS IMAGE WAS CREATED: 

The main priority in creating the image was to be as accurate as possible.
This does not only apply to the bridge itself but also to the environment.
So the landscape at the horizon, the lanterns and the island of Inchgarvie
with its ruin on top are there in reality.

The bridge was divided into several sections i.e. the central tower and the
two towers on either side, the two suspended spans and the six cantilevers as
well as the approach viaducts. The main problem was that there were no
accurate detailed drawings avaialable. The main source for constructing the
objects mentioned above was a reproduced blueprint depicted in the 2nd book
mentioned above. However, it did not contain many readable figures. So
measurements had to be taken by comparison and angles were calculated
trigonometrically. In the end constructing the bridge became quite difficult
due to crowding.

The skysphere and the water surface were taken from the include files which
came with Povray. However these were altered to give the right impression.

The view is in north eastern direction and in order to hide the landscape
(15 to 20 miles away) there, the horizon was kept foggy using a ground fog.

The ship was placed in the image to give some idea of the size of the bridge.
The ship.inc file will be included in the zip file and can be freely used as
an object in your scenes. It might require a certain amount of additional
work but it looks fine from a distance.

By the way, I would appreciate some comments regarding the waves made by a
moving ships in stills as well as animations. 

Some files are included in the zip file to illustrate the complexity of the
task. I do not include all files as I spent one month constructing the bridge
and
I would like to explore other views prior to releasing the complete source
files.

The real problems were not associated with construction. That task was only
time consuming. A real problem was getting the fog, lighting etc. properly set
up
to minimise post processing. However, on conversion to a jpeg image using
Ulead Photoimpact 3.2 the image deteriorated dramatically and only small
adjustments in contrast/brightness gave acceptable results. The image submitted
is still inferior to the original image which I may offer for download on my
home
page (s.a.) in a few months time.

The final run to get the image submitted contained over 180,000 objects.






