Chaos Group

V-Ray render engine in action for Avatar!

Exclusive interview for 3DVF with the French 3D artist Aymeric Aute from Prime Focus VFX. He shares his experience during his creative work for the James Cameron's epic motion picture Avatar. He takes us to an impressive trip across his professional history, explaining his migration to the 3D and the opportunity to be part of the starting team on Avatar.   

This interview is provided by the courtesy of 3DVF.
Read the original interview in French.

I'm 35 years old, I live in LA for 1 year and a half, I'm working for Prime Focus VFX, Frantic VFX previously. I am autoditacte in parallel the high school and my studies of geology, I have learned by myself the 3d and after that with a group of buddies on Montpellier (Puls'art) in 1995.

I then began my career with ups and downs in moving a lot in France - Montpellier, Chambery, Lyon. Then came the opportunity to return to Paris where I became independent. I worked on in interesting projects, as the sequence of Pinball for the Johnny Holliday tour in 2006. Since that time I specialized in Lighting and Rendering.

Then I incorporated a real Highlevel team with a strong creative atmosphere. I have really enjoyed that period where i can dig all my creativity and experimenting new technical and artistic stuffs. I invite you to visit their website www.i-reel.fr.

My desire to move and the dream that I've always had to work for big prod have always followed me during this period. I applied to 5 selected studios in Spring 2008. 3 Months after I started on Gi Joe in Prime Focus VFX, the textures, shaders, lighting and rendering on the sequences with Nigthreaven and missiles. I had to learn the whole process of creation and the pipeline inherent in such large projects (more than 140 shots).

Then in April 2009, I integrated the starting team on Avatar. We worked especially in interior shots with screens and holographic table (op-center, lab, Parker desk, jail) and a huge shot on the tarmac.
I have been responsible for rendering Ligthing under the supervision of Mitch Gates (CG Supervisor, Prime Focus VFX) and Chris Bond (President / Senior VFX Supervisor, Prime Focus VFX). On Some shots I have also realized the modeling and animation, and for the first time a script containing more than 2 lines :).

Video Diary
I had in my hands the original camera , that Jack uses to record his diary (Video Diary) during the film. I made the 3d models, textures and shaders under 3dsmax2008 and V-Ray.  Once the tracking team has finished its work, it gave me a layout (camera, location and orientation of elements of the scene), where I placed my object and I began the lighting. I mainly use a V-Ray-dome light with HDR map that I've recreated from photographs on-set, as well as V-Ray lights to accentuate certain effects and reflections.

I created several passes through V-Ray Render Elements for my render, which can vary from 5 to 20 depending on the level of detail that you want to manage during compositing. Even if the renderfarm is quite big (200 machines) and you are never alone in the stack (other plans and other prod sometimes the studio in parallel) we must optimize the scene and rendering parameters (DMC sampler, V-Ray-system. ..) to provide time for composers.

When i lighted, the main difficulty came in managing reflections when rendering stereoscopic for metal objects or transparencies. In fact we submit 2 renders for each shots (right eye and left eye) and the 2 cameras are slightly apart from the one to the other with a small offset angle. These 2 parameters vary depending on where the focus point is located in the 3D scene. So in general we worked on one of the eyes and adjusted the lighting for the second one if there are differences.

Unobtanium rock
In several sequences Parker plays with a fragment of Unobtainium, the famous rock that is so expensive and the first issue of their presence on Pandora. The rock property taken from its fleet of over the base.
Here again I replicated the fragment from the one used on the set.
Modeling quasi-low-poly to be closer than the general shape and generation of a displacement map in photoshop (because after a test in Zbrush I preferred the reflection map generated by my semi-procedural texture), as well as textures and mapping from a photograph taken by us.
Once all has been valid, I incorporated into the tracked shots. I also used for the lighting an HDR recreated from photos taken on-set. The same HDR is used for the reflections in the rock. And I recreated a virtual photo studio (V-Ray lights and autoilluminated planes) to adjust the reflection.
I used a low poly Hands to generate the reflection, GI and contact shadow of actor hand into the rock.
I also created the base model to regenerate the blue halo issued by it and receive the reflection of the Unobtainium fragment . I made the rock animation to simulate the zero gravity floating effect generated by the base. Shots are rare and interesting because I've almost done everything except tracking and final comp, instead of being confined only has a specific task.

Holotable
Creation of shaders and lighting for more than 50 shots. During the shooting the inside holotable hardware consist in a green cloth (only the outside of the table is hard). On each shot i had to be closer to the existing lighting (daylight or night, and all internal light source) and in some cases generate the shadow cast by the actors (I uses for this low-poly characters). There are over this layer R, G and B beams generating the holographic image (of a transparency and rapidity of the beams and for reasons of computing time I used the good old technique with motion blur multi-pass effect). Hologram for him even as I worked on some shots (animated one) or I have to generate 32k maps (beauty, bump, displace, reflection) that I animated using an internal script linking UVmap modifier to a gizmo.
For closer shots Anselm von Seherr Thoss and Charley Carlat used the V-Ray-proxy to reproduce the jungle and Krakatoa for LIDAR effect (satellite image).

Tarmac sequence
The last shot where I worked during the last month. Parker looks out the bay window the preparations on the runway. 6 seconds in full CG where I had to create shaders for vehicles. The main difficulty has been to stick perfectly with the references we received from WETA and ILM, which had already finalized shots with the same types of vehicles. So I shaded the Dragon, scorpion and samson (aircrafts
vehicles) and some others items on the runway.I also created (in relation with the Prime Focus matte painting department of Ken Nakada) the wet map and humidity shader of the runway. Due to the big amount of data 3 persons has been working for the lighting and rendering - Andrew Roberts, Rob Ward and I - to generate 64 passes per eye excluding masks adjustments, FX and mattepainting for the refinery in the background.
At the very end, I even completed some aircrafts animations to respond to the degree of requirement that James Cameron has been throughout the creation of his film in all the details.

I also Lighted all vehicles flying in the background. For the occasion I created a reprojection script to correct  stereoscopy problems of distant elements. And created some glass screens in the guard room.

6 months of real pleasure with a strong and fun team...

Best regards,

Aymeric Aute

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Copyright: 2009 Twentieth Century Fox. All Rights Reserved
Image Courtesy of Prime Focus

Read the interview with Anselm von Seherr Toss on the same project.