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Curve Process in Hair Synthesis

Shuo Wang 1  Kun Zeng 1 and Song-Chun Zhu1,2
1Lotus Hill Institute;  2University of California, Los Angeles

1. Why Curve Process?

 Synthesis human hair by sampling in random field[1] shows satisfied performances, it is so smooth, however, that even not has an overlapping between two hairlines since this method is based on vetor filed. This problem may lead to a littel rigid and unnature when synthesis. In order to enhance the artistic effects of the synthesis, we need more elegant and interlacing lines through curve process.

2. How to do?

 (a) trace point (b) input image (c) trace along with vetor field (d) result

 In Curve Process, it is curves but not sampling being used to synthesis hair. Our method first constructs an elastic function to describe a curve, and then for every start point we use this function to trace a line along with the vector field. Finally, for the purpose of getting smoother and more elegant lines, we choose, such as Cubic Spline, Bezier Curve and Euler Spiral, curves instead of the straight lines to connect the neighbor trace points.

 Here is an example for curve process. (a) shows how to trace a next point from the current one. By contraining the difference of angle and the length of trace line, we propose the next point and determine whether it should be accepted. When given an image as (a), users need assign a region including start points as the green rectangles shown in (b), and then along with the vetor field(b), points on one hairline can be traced. (d) is the result of connecting by euler spiral.

3. Some Results

4. References