Mumbai based SciClone Motion Graphics has worked on the Visual effects and CG of the new Mahanand milk advertisement which features 3D crowd generation.
Speaking to Animationxpress.com about the objectives to be achieved in regards of VFX in this TVC, SciClone Motion Graphics Director Evon Reddy shared, “The objective of the project was to replace empty stalls in the stadium with a crowd of 5000 people. Some technical and creative challenges to overcome were: A large amount of variation in the crowd in terms of age, height, clothes and actions was mandatory, some shots had extreme perspectives and close-ups and with over 20 such shots, many shots had fast and freeform camera motion.”
The TVC boasts of billboard based crowd generation using Sprites. Sprites refer to a partially transparent two dimensional animation that is mapped onto a special plane in a three dimensional scene. Unlike a texture map, the sprite plane is always perpendicular to the axis emanating from the camera. The image can be scaled to simulate perspective, it can be rotated two dimensionally, it can overlap other objects and be occluded, but it can only be viewed from the same angle. This rendering method is also referred to as Bill-Boarding.
Talking about the VFX, Evon said, “The technique we utilized, involved shooting each person against a chroma background. We took about ten shots of each person performing random actions such as sitting and cheering, standing and cheering, jumping, waving etc. We shot 50 such people which totaled to 500 shots. These shots were then processed to isolate the chroma background and edited converting them into loop able actions. All 500 loop able actions were then moved to a library, to be later utilized in 3D.”
She further added, “We then generated a 3D proxy set of the stadium to place our shots. Camera tracking was done to extract the 3D motion of the camera from each live action shot. We extensively used particle system, where-in each particle represented one person. The particles were placed in the stadium with a random offset to break the pattern and linked with a random action in our library. We sampled image sequence of characterâ€?s motion from each direction and the particles were then rendered using the Billboard technique to enhance performance.”
With a six member team, the VFX work for this advertisement was finished in two weeks from the day of shoot including shoot supervision.
“The main challenge was generating people; as they should not look the same, nor behave the same, with the parameterization of integrating them in virtual environments. Crowd simulation for virtual environments offers many challenges centered on the trade-offs between rich behavior, control and computational cost. We achieved our aims with a situation-based control structure. Basic crowd has very limited behaviors. As they enter new situations, additional, situation-specific behaviors are incorporated on the fly to enable the crowd to respond appropriately”, said Evon when asked about the challenges while doing VFX for this ad.