Researchers have developed a novel algorithm that computes the shape of the surface at rest, and when this shape is deformed under gravity, contact and friction.
Simulating any 3D surface or structure, from tree leaves and garments to pages of a book, is a computationally challenging, time-consuming task. While various geometric tools are available to mimic the shape modeling of these surfaces, a new method is making it possible to also compute and enable the physics, movement and distortion, of the surface and does so intuitively and with realistic results.
Researchers from Inria, the French National Institute for computer science and applied mathematics, have developed a novel algorithm that computes the shape of the surface at rest, that is, without any external force, and when this shape is deformed under gravity, contact and friction, it precisely matches the shape the user has designed.
Users draw or design any 3D surface utilizing their preferred geometric tools and can then turn to the new computational method to convert the surface into a physical object, and one that may or may not make contact with other surfaces
Many geometric tools exist to perform accurate modeling of shapes with flexibility given to the user. Given the example of modeling clothing around a 3D character, the researchers' method provides a simpler way for the clothing to mimic movement on the animated character, automatically computing for gravity and frictional contact with an external body.
The scientists note that the major difficulty in this kind of inverse problem stems from the fact that it is highly nonlinear
This complexity is particularly exacerbated by the presence of contact and dry friction, which was never explicitly accounted for in previous studies. It is thus challenging to design a robust algorithm able to find a valid rest shape for a large variety of different scenarios.
The researchers provided several examples in the paper, showcasing their algorithm's performance on 3D animated designs. Included in the paper are two hat examples, noted as 'floppy hat' and 'beret', which are posed on a human head through contact and friction. Without the researchers' inversion method, the floppy hat sags, completely losing its original style and partly covering the face of the animated character. In contrast, after running the new algorithm, the hat preserves its original style and realistically flip-flops with the movement of the character.
The beret example produced similar realistic results after applying the team's method, the beret correctly remained inflated and posed on the head. When 'wind' is applied to the design, the beret slides with the movement but does not fall completely off the head, exemplifying the algorithm's ability to realistically simulate the physics involved.
In future work, the team will focus on making their algorithm work faster and be adapted to the creation of real garment patterns.