TITLE: Minimum
NAME: Bertrand Petit
COUNTRY: France
EMAIL: irtc@phoe.frmug.org
WEBPAGE: http://www.bsd-dk.dk/~elrond/
TOPIC: Minimalism
COPYRIGHT: I SUBMIT TO THE STANDARD RAYTRACING COMPETITION COPYRIGHT.
JPGFILE: bpmini.jpg
ZIPFILE: bpmini.zip
RENDERER USED: 
    Povray v3.6.1

TOOLS USED: 
    emacs; make; FontForge

RENDER TIME: 
    11 hours

HARDWARE USED: 
    Pentium IV clocked at 1.7_GHz

IMAGE DESCRIPTION: 


This image is an evolution of a design I used as a unique seasons
greetings card. That card was sent to a friend following a discussion
we had about how I use the word "minimum" to evaluate some qualities
or defects of non-decorative type faces. The greetings card had that
word set almost as it is in the present image, it also had a
signature.

I thought that the adaptation of this paper card to a raytraced
rendering would be a perfect match for the minimalism topic.

We're dealing here with raytracing so I could not only lay a flat word
on a plane, it had to protrude somehow in order to cast shadows. These
are deep shadows, that's a deliberate choice at they permit to render
the word with a maximum effect on the viewer using only a very limited
number of features on the image.

I'm quite satisfied of the result. I'm so satisfied that I took the
opportunity to try the Zazzle service. You can have a look and by a
print at the following address:
<URL:http://www.zazzle.com/link.asp?associate_id=238620031415155215&redirect=prod
uct&product_id=228125601502764875>



DESCRIPTION OF HOW THIS IMAGE WAS CREATED: 


Povray version 3.6 was used to render the image. The word is just a
Povray text object using the Bubbleboy type face as geometry source.
This type face was designed by Jakob Fischer
<URL:http://www.pizzadude.dk/>. Unfortunately that font file missed
some of the tables used by Povray to access glyphs. I had to
regenerate the font file using FontForge. I also had to make a minor
change to the font: the designer did align all curved letters on the
baseline. Designing letters this way generates unwanted visual
effects: the word appeared unevenly aligned, it looked as if the U
letter was shifted upward. Again FontForge was used to tailor the
font. The font was specially chosen for that scene from the set of
freely available fonts of the DaFont repository.

The lighting is very simple: just one spherical area light. I made
some tests with a second source to lighten the shadows. That move
revealed itself as a bad one as it lessened the effect of the picture
even when that second light was configured to cast no shadows.

The scene use radiosity even if the influence on the picture is barely
visible. That effect is nevertheless important as it creates a
lighting difference between the top of the letters and the underlying
plane. Without radiosity the top curves appears to blend with the
background and that's not desirable.

Initially the background plane had just a plain white pigment. When
the image was rendered at higher resolutions, the different shades of
gray appeared as concentric circles due to the limited number of grays
representable using 8-bit numbers. That was not acceptable. However
there is an easy trick to overcome this limitation: add some noise.
This tricks the eye and the brain to see more shades of gray than
there actually is in the image. Several texture tests were made and I
settled for a agate-based normal perturbation for both the text and
the supporting plane: this looks almost as paper illuminated by a
skimming light. Considered the origin of the scene idea I thought that
was a bonus.

I experienced some difficulties with radiosity settings. Povray lacks
a good documentation about the various settings, their effects, and
which setting to alter in order to correct common kinds of artifacts.
So I had to arbitrarily increase or lower most of the radiosity
parameters in order the remove blotches and spots appearing on the
supporting place, this partially explains the long rendering.
Considering that Povray implements Greg Ward's global illumination
algorithm, it would be nice if the Povray documentation team could use
radiance documentation and some material in the book Rendering with
Radiance by Greg Ward and Ron Shakespeare as a basis for a better
documentation. A mapping from Radiance to Povray parameter names would
had been enough to me.

The area light is another source of intensive computation. I wanted
the scene to have absolutely smooth penumbras to contrast the sharpness
of the word and the deep shadows between the letters legs. The
smoothness of penumbras is directly related to the number of
sub-samples used for the area light. Unfortunately the smoothness is
also an inversely related to the rendered image size: when penumbras
surface raises, one must also raise the number the area light
sub-samples to avoid banding effects.

The exact rendering time is unknown as I rendered the same scene three
times with decreasing resolutions, each one benefiting from the
radiosity calculations accumulated by the previous run. The image
submitted to the contest was the last being rendered. Another source
of imprecision on the rendering time is Povray itself because of a
feature I view as a bug: it reports wall clock durations!


 LocalWords:  WEBPAGE FontForge Zazzle Bubbleboy DaFont bpmini txt

Here ends the bpmini.txt file.