TITLE: Light trails
NAME: Bill Pragnell
COUNTRY: UK
EMAIL: billpragnell@hotmail.com
WEBPAGE: http://www.infradead.org/~wmp/
TOPIC: Speed
COPYRIGHT: I SUBMIT TO THE STANDARD RAYTRACING COMPETITION COPYRIGHT.
JPGFILE: wp_trail.jpg
ZIPFILE: wp_trail.zip
RENDERER USED: 
    POV-Ray 3.6.1

TOOLS USED: 
    none

RENDER TIME: 
    ~230 hours

HARDWARE USED: 
    AMD 900MHz 128MB... perhaps it's time to upgrade...

IMAGE DESCRIPTION: 

The vivid headlamp streaks brought out in long-exposure photography of
night-time traffic have always suggested intense speed and busyness to me.
The topic is also reflected in the implied speed contrast: fast traffic vs
slow camera shutter. This effect is one that I've never before seen in CGI
imagery; once the idea had occurred to me, I decided I just had to give it
a go.


DESCRIPTION OF HOW THIS IMAGE WAS CREATED: 

It was clear from the outset that if modelling a curved or sloped road
would be tricky, the corresponding light trails could easily be even
trickier. Although I initially experimented with high-ambient
sphere_sweeps, it soon became apparent that emitting media would be
required to produce the glow effect. I therefore resolved to keep the road
geometry as simple as possible so I could concentrate on detail and
lighting.

The image was hand-coded in POV-Ray SDL. The architecture is all CSG,
mostly employing bevelled edges for realism. All surfaces have either
granite or crackle normals. The road texture, largely masked by the light
trails, was created using a turbulent gradient; the road markings are
boxes, not textures. The chain barrier uses very simple circular arcs of
chain (I didn't have the inclination to tit about with hyperbolae or
catenaries), and the water beyond is a simple reflective bozo normal. There
are several very tall, very luminous cylinders out of sight about 200m away
to generate the reflections, as well as some bright blue sky near the
horizon (think near dusk). The lamp-posts are similarly CSG, with emitting
media glows. The light trails are randomly placed pairs of cylinders
comprising a high-ambient solid core surrounded by a cylindrical-density
emitting media.