— technique —

My goal is to give my artwork the weathered look of medieval paintings. To accomplish this, I create custom shaders and compositing networks using Side Effects' Houdini software. The shaders cover the painting with craquelure (a pattern of tiny cracks), stains and grime. I also wrote a brush-stroke shader which takes into account the shapes of objects in the painting. This makes it possible to procedurally recreate the look of brush strokes applied by a human painter.

I use various CG techniques to create backgrounds, crowds, and high-detail areas— just as old masters employed apprentices to handle the more mundane aspects of their paintings.

Cavalry

Cavalry created with a crowd system

Distressed wood (digital)

Simulated craquelure
(based on an L-system)

Riders processed with a paint shader.

Researching craquelure led to interesting findings. As it turns out, not all cracks are created equal.

Cracked mud

Mud cracks are typically non-hierarchical. Drying mud breaks up uniformly into regions of similar size, which have 6 sides on average.

Craquelure on the Mona Lisa painting

Craquelure is usually hierarchical. Cracks accumulate over time, forming progressively finer lines. The subdivisions tend to be rectangular rather than hexagonal.

Hierarchical crack pattern

In a hierarchical pattern, cracks form localized regions, which resemble city blocks on a map. Note how width varies among hierarchies.

Hierarchical cracks

Hierarchical cracks on glazed ceramics

Simulation of hierarchical cracks

Hierarchical pattern generated with a computer simulation. Stained glass window, perhaps?

Simulation of hierarchical cracks
Hierarchical cracking in action.
Who said watching paint dry is boring?