TITLE: The Forth Railway Bridge NAME: David Wilkinson COUNTRY: Scotland EMAIL: davidwilkinson@cwcom.net WEBPAGE: hamiltonite.mcmail.com TOPIC: Landmarks COPYRIGHT: I SUBMIT TO THE STANDARD RAYTRACING COMPETITION COPYRIGHT. JPGFILE: forthbri.jpg ZIPFILE: forthbri.zip RENDERER USED: POV-Ray 3.1g TOOLS USED: PSP for converting tga to jpg RENDER TIME: parse time 36 seconds; total rendering time 48 minutes 6 seconds. HARDWARE USED: PII 350 - 64Mb IMAGE DESCRIPTION: The railway bridge over the river Forth in Scotland is a landmark in many senses of the word. Built in 1890 it was the first large structure built entirely of steel. It dominates the landscape now, just as it did when it was first built. Its design in 1881 by John Fowler and Benjamin Baker was a tour de force of its age and, following the Tay Bridge disaster of 1879, was a courageously bold statement of engineering endeavour. The bridge's full length is 1.2 miles, it took 7 years to build and cost the lives of 57 men. It was fabricated on site from 51,000 tons of steel plates and steel sections using over 7 million rivets. The image shows a view from upstream of Queensferry. I have shown a 1930's steam locomotive on the bridge and although this is to scale and is fully detailed, the size of the bridge's structure is such that the locomotive appears insignificant. From being built, the bridge was painted with red lead paint and it remains that way today - a patchwork of rust and red paintwork. DESCRIPTION OF HOW THIS IMAGE WAS CREATED: The bridge is defined to a scale of 1 POV unit = 1 foot. It is all hand coded (using POV's built-in editor) of standard CSG elements - boxes, cylinders, cones and prisms. Initially I had a struggle getting dimensional information on the bridge. There is a web site, but this was not very helpful for my purposes. My first breakthrough was locating a book on Amazon(John Fowler, Benjamin Baker, Forth Bridge; Axel Menges 1997). This book contains a selection of magnificent photographs, and, more importantly for me, reproductions of some scale drawings of the bridge. This arrived on 30 July and my work on the bridge started from that date. A response to an email to the originator of the web site gave me another lead. The centenary of the bridge in 1980 was celebrated with a re-issue of the book by Wilhelm Westhofen published by Engineering magazine in 1880 - and this was freely available for borrowing through my local library! This wonderful source document is a detailed account of the design and construction of the bridge with many scale drawings and contemporary photographs. Unfortunately, the possession of source drawings still leaves a lot of dimensional information to be scaled, calculated, or just guessed. I now have dozens of sketches and calculation on pieces of paper, and, on looking back at those I made just a couple of weeks ago, they are as unfamiliar as my school notebooks of many years ago. The image, is, of course, unfinished. There is the question of the shorelines for instance - obscured by a convenient sea mist in my image :-) and there are many more girders to be painstakingly added. The stone piers have given me some problems. I used the brick pattern with granite textures, and on the sloping walls of the pier this gave rise to hideous artifacts (courses of mortar where there should be bricks). After some experimentation I managed to minimise this by rotating the texture to 10 degrees greater than the slope of the walls. In spite of these imperfections and missing details, I think the image gives a pretty good idea of the power of the structure. I hope you like it. Image Statistics; 69,047 objects; memory used 65,691,942 bytes; Antialias=On; Sampling_Method=2; Antialias_Depth=2; Antialias_Threshold=0.1; Radiosity=1 (The zip file contains the macro for the lattice girder used extensively in the bridge and the source for the Pier seen in the image.)