By Darren Waters
Technology editor, BBC News website
Project Gotham Racing 4 features bikes and cars
Driving through the rain-drenched streets of Shanghai in an Aston Martin DB4 at breakneck speeds, with the neon signs of shops blurring as you pass by, is one of the great thrills in life - even if it is only virtual.
Video game development has made tremendous graphical strides in the last four decades and nowhere is this more pronounced than in driving simulations.
In the 1970s a driving game was a simple mix of black and white pixels that were manoeuvred between two moving lines to represent the road's edge.
One of the first such games, Night Driver, had a plastic representation of the car that was laid under the screen of the arcade machine.
Games like Pole Position in 1982 and Outrun in 1986 pushed the genre on with 3D graphics and a growing emphasis on realism.
But today's games offer an experience that is unrecognisable from the blocky and crudely drawn efforts of the past.
Games such as Project Gotham Racing 4, Ferrari Challenge and Gran Turismo 5 offer photo-real cars with simulated handling physics, being thrown about in high-definition worlds, which often recreate real cities in astonishing detail.
"We're not trying to simulate reality," says Alan Mealor, lead environment artist at Bizarre Creations, developers of Project Gotham Racing 4 (PGR4).
"There's no point in creating a richly detailed world if it can't run in the game," he adds.
Bizarre have to trade off hyper-realism with the hardware's ability to handle the complexity and detail of a world and have cars run smoothly inside the game.
PGR4 takes drives on a tour of eight cities - Macau, Las Vegas, London, St Petersburg, Tokyo, New York City, Shanghai, Quebec - and each location took one of four teams of five artists 18 to 20 months to build.
"We start with research; books, magazines, the internet - anything to get a feel for a place," says Mr Mealor.
He adds: "We try and get our hands on anything we can - from A to Z maps, to documents from New York's Town Hall for that particular city."
After short listing the cities Bizarre sent out a team to each of the locations to look for any potential problems first hand.
Race some of the world's best cars - virtually
Mr Mealor says: "Cities have a nasty habit of changing. Macau looked perfect for us first of all.
"But in the space of two years they had built two casinos, the road layout had changed dramatically and they had reclaimed lots of land."
The work to recreate a city then moves to digital photography. The artists used a bank of digital SLRs to take photos of every aspect of a location.
"In Macau we took 240,000 photos. Everything from pavements to litter bins and every sign on a building.
"We have a two-week trip just taking photos."
In all, in excess of two million photographs of various locations around the world were taken - and then the hard work began.
Each of the cities in PGR4 is drawn by hand. The team does not use GPS data because it is not accurate enough and software that converts digital photos into real world geometry is eschewed in favour of an artist's talent at capturing the "feel" of a location.
"I want the cities in the game to feel like they did when we walked around them," says Mr Mealor.
The artists use software application Photoshop to draw the worlds and Maya to build the cities in three dimensions. At the end of the process each city is more than 6.3GB in size, across 10,487 different files.
That data is crunched down by a render farm into a size manageable by the Xbox 360. The team even uses pre-production 360s to help export the data.
At the end of the crunch a city is only 593MB in size, held in just three different files.
The hardest part of the process, says Mr Mealor, is lighting.
"The importance of lighting is always overlooked. It's unbelievably important.
"You take it for granted when walking around a city: The light on concrete, tarmac, and cars."
The attention to detail and growing realism is one of the reasons racing titles remain such a popular gaming genre.
Mark South, a producer at Eutechnyx, working on multiplatform title Ferrari Challenge, says authenticity was the guiding principle.
"The mission statement for us was to recreate the feeling of a Ferrari experience. Getting all the real world data into the game requires a lot of reference."
His team travelled to far flung corners of the world to track down rare Ferraris, taking between five and 7,000 digital photos of each vehicle.
In all, the company gathered more than 3.3 terabytes (3,417GB) in data for its cars and tracks.
"The time taken between taking photos of a car to putting it in the game is about 2.5 months, with two people working on it day in, day out," says Mr South.
Eutechnyx were provided digital blueprints, known as CAD data, for many of the cars from Ferrari itself, as well as service manuals.
The company also hired the services of Grand Prix 2 driver Bruno Senna to test the accuracy of virtual handling.
"If you're going to create a simulation you need to know that it drives like the real thing," says Mr Mealor.
"We took a virtual Ferrari 430, took it on a virtual track and recorded the telemetry. Then we took a real 430 and took it to a real track and again recorded telemetry to make sure it matches up."
At Bizarre, the firm also used CAD data for some of the cars and for certain others used miniature models, photos, manuals and first-hand experience of the vehicles.
"It takes four to six weeks to build every car - from nothing to being in the game," explains car artist Jason Bowers.
"We wanted the cars to look super realistic."