Abstract
We propose a new methodology for creating 3-D models for computer graphics applications from 2-D concept sketches of human characters using minimal user interaction. This methodology will facilitate the fast production of high quality 3-D models by non-expert users involved in the development process of video games and movies. The workflow starts with an image containing the sketch of the human character from a single viewpoint, in which a 2-D body pose detector is run to infer the positions of the skeleton joints of the character. Then the 3-D body pose and camera motion are estimated from the 2-D body pose detected from above, where we take a recently proposed methodology that works with real humans and adapt it to work with concept sketches of human characters. The final step of our methodology consists of an optimization process based on a sampling importance re-sampling method that takes as input the estimated 3-D body pose and camera motion and builds a 3-D mesh of the body shape, which is then matched to the concept sketch image. Our main contributions are: 1) a novel adaptation of the 3-D from 2-D body pose estimation methods to work with sketches of humans that have non-standard body part proportions and constrained camera motion; and 2) a new optimization (that estimates a 3-D body mesh using an underlying low-dimensional linear model of human shape) guided by the quality of the matching between the 3-D mesh of the body shape and the concept sketch. We show qualitative results based on seven 3-D models inferred from 2-D concept sketches, and also quantitative results, where we take seven different 3-D meshes to generate concept sketches, and use our method to infer the 3-D model from these sketches, which allows us to measure the average Euclidean distance between the original and estimated 3-D models. Both qualitative and quantitative results show that our model has potential in the fast production of 3-D models from concept sketches.