Physically Based Rendering

Rules for Physically Based Rendering

Physically Based Rendering (PBR) are a set of rules to achieve a believable look. These images follow PBR rules in a more ore less strict manner.

  • Do not violate energies conserving laws. An object can not emit more energy, in this case light, than it receives.
  • Make a distinction between metallic and dielectric materials. They reflect in a very different manner.
  • How reflections can be seen on a surface depends on the viewers position relative to the object. On gracing angels we have reflection, but not at facing angels. This is called the Fresnel effect.
  • Diffuse looking materials reflect the environment, but more blurry compared to metals.
  • In the real world every surface has roughness, even a mirror.
  • There are no sharp edges in real world objects.
Real world photos used

Most of these images are based on two photos.

  • For the environmental light HDRI images from www.hdriheaven.com are used. They serve as a light source and can be seen in reflections.
  • To texture the object a second photo is needed. This is the source of the albedo color.
  • And this photo will be used for mesh displacement.

Software used

  • Clojure to describe the geometrical structure.
  • OpenVDB to fill narrow-band level sets with spheres and export a single mesh covering all spheres.
  • Blender to assign material properties to the mesh and illuminate the scene with light sources.
  • Cycles or LuxCoreRender to render the images.