February 2010 Archives

You never see a flat rollercoaster track go into a perfectly circular loop-the-loop because while that track is continuous in the first derivative, it is not continuous in the second derivative, and would make for a very jarring ride.

Entering the circular loop from a horizontal track would imply an instant onset of the maximum g-force (as would a direct transition a circular path with smaller radius of curvature). An immediate transition from one radius of curvature to another would give a continuous, smooth track, but with discontinuous second derivatives. Clearly, a function with continuous higher derivatives would be preferable.
Roller Coaster Loop Shapes

So is there a special curve with which to make the optimal photo studio wall?

This is why car surface designers, who are in many ways reflection pattern designers, worry about continuity and smoothness in the higher derivatives.

- A Periodic Table of Form: The secret language of surface and meaning in product design by Gray Holland

In the early 80's, Gene Miller and Christine Change went into the parking lot of MAGI, one of the major TRON CG vendors, and photographed a Christmas ornament.

They imagined the sphere as reflecting the interior of an infinite cube, which caused the sphere to be divided into 6 regions, one for each face of the cube. The far cube face is squashed into the yellow zone at the glancing angle outline of the sphere.

Notice how on other objects the analogous relationships are maintained: the upper plane (in blue here) is always on top. The right plane (in red here) is always on the right...

Classic '70's airbrush art chrome, as in this Sorayama 'sexy robot,' are actually reflecting warm earth and cool sky separated by a dark horizon.

...as is the chrome hubcap in the inset photo.

UPDATE 3/25/2010

Maxwell Render Gold test with roughness values of, 33, 66, and 99

A little Valentine's Day image featuring the super cool Nekromistress.

I wanted to try and make a strong color statement - something along the lines of the work of Brian DeMint / Eyeworks of Joplin, Missouri.

I'm interested in trying to simulate things like tintypes using digital techniques.

I think the best way to do it is not to just use Photoshop tricks, but to model and texture a surface and render it in Maxwell, paying special attention to surface textures and materials and reflectivity.

Before I can do that, however, I need t have a good look at a few of these things. I want to hold them in my hand, flex them, scratch them, see how they reflect light.

I bought a few on eBay. Surprisingly cheap for small ones. I am scanning them on flickr in this set: Tintypes

I'll update this blog entry as my experiments in this area progress...

UPDATE 2/15/2010

model: Nekromistress

This is a straight Photoshop composite using some textures from some scanned tintypes I bought on eBay. To really do it up, I want to bring Maxwell and ZBrush into the mix. I haven't done so, yet.

For my daughter's 6th grade Science Fair experiment she chose to explore the Inverse Square Law as it relates to light falloff. Technically the ISL only relates to point light sources, and it will 'fail' when the lights are not point light sources, but just how badly does it fail?

Any light is approximately a point light if you get far away from it. So how accurate is the ISL in real world cases? I was actually pretty curious to find out, myself.

So without further ado, here are the results of our experiments, courtesy of my 12-year-old daughter...