minning.de - Stefan Minning: CG Artist and Developer

What started out as a set of sim­ple plug-​​ins for After Effects has devel­oped into a com­plex shad­ing and light­ing solu­tion over the years — the soft­ware is no longer lim­ited to mere dif­fuse or spec­u­lar light­ing: It cur­rently includes sup­port for fake reflec­tions, refrac­tions, subsurface-​​scattering, screen-​​space ambi­ent occlu­sion and even a very sim­pli­fied global illu­mi­na­tion model, many of which were used dur­ing the pro­duc­tion of A Night at the Cathe­dral. Thanks to these tools our ren­der times were only a frac­tion of what a full 3D ray­trac­ing ren­derer would have required.

Wire­frame show­ing how the cathe­dral was split into sev­eral inde­pen­dent parts

While part of the team was busy ani­mat­ing and shad­ing char­ac­ters, oth­ers began cre­at­ing back­ground mattes for all 30 shots, which meant mod­el­ing a medieval cathe­dral and its sur­round­ings from the ground up. Obvi­ously a cathe­dral and its inte­rior is an enor­mous and highly detailed scene which can be quite a bur­den even on state-​​of-​​the-​​art soft– and hard­ware. Con­se­quently the poly­gon count for indi­vid­ual objects was kept as low as pos­si­ble.
To make work­ing with this 12.000.000 poly­gon scene bear­able, we split the cathe­dral up into more than a dozen blocks, each per­tain­ing to a spe­cific area and which could be imported on a shot-​​by-​​shot basis.
Wher­ever it made sense, instanc­ing was used in order reduce the scene’s mem­ory foot­print: For exam­ple, the side of the cathe­dral is com­prised of a dozen iden­ti­cal instances of a sin­gle wall piece that are auto­mat­i­cally repeated and thereby save a lot of mem­ory. The same is true for benches, stained-​​glass win­dows, chan­de­liers and many other com­plex details inside the build­ing.

PANDA was used to gen­er­ate the non-​​photorealistic look on our 3D models

Both the cathe­dral model and tex­tures are basic in terms tech­niques applied — just clean poly­gon meshes and medium res­o­lu­tion tex­tures includ­ing dif­fuse, bump– and normal-​​maps. Our trick to cre­at­ing the painterly back­grounds seen in the film was Stu­dio Lam­pion’s pro­pri­etary non-​​photorealistic 2.5D ren­derer, PANDA (Paint AND Auto­mate). This tool auto­mat­i­cally repaints scenes using actual strokes painted by an artist by con­vert­ing the loca­tion and direc­tion of these 2D brush strokes into actual 3D space. It thereby becomes pos­si­ble to auto­mat­i­cally repaint the scene from arbi­trary per­spec­tives. The brush strokes remain coher­ent over time to avoid the noisy flick­er­ing effect sim­pler 2D paint solu­tions may exhibit.

Back­ground ren­dered with PANDA with addi­tional 2D details

After hav­ing PANDA cre­ate a painterly base for a shot, we brought these back­ground lay­ers into Pho­to­shop for basic cleanup and adding addi­tional detail in 2D. Often ref­er­ence pho­tos of stat­ues and orna­ments we had taken in cas­tles and churches dur­ing the pre-​​production phase were used to embell­ish the back­ground mattes by first extract­ing a normal-​​map from the photo and then con­form­ing the col­ors and over­all light­ing to the back­ground environment’s.

Finally, every­thing was brought together in After Effects where we added spe­cial effects such as fire, snow and fog to the shots and inte­grated char­ac­ters and back­grounds by mak­ing the light­ing match using Nor­mal­ity.

The pro­duc­tion of A Night at the Cathe­dral was fin­ished in Novem­ber ’08 after about eleven months of work. Stu­dio Lam­pion is cur­rently refin­ing cer­tain ele­ments of the film based on the feed­back we received from our screen­ing audiences.

Arti­cle first pub­lished in 3D Artist mag­a­zine.