NeuralHDHair: Automatic High-fidelity Hair Modeling from a Single Image Using Implicit Neural Representations

HairStep: Transfer Synthetic to Real Using Strand and Depth Maps for Single-View 3D Hair Modeling

“…Inspired by the advances of learning-based shape recon-struction, 3D strand models are generated by neural networks as explicit point sequences [46], volumetric orientation field [26,30,41], and implicit orientation field [37] from single-view input. With the above evolution of 3D hair representations, the quality of recovered shape has been improved significantly.…”

“…With the above evolution of 3D hair representations, the quality of recovered shape has been improved significantly. As populating pairs of 3D hair and real images is challenging [46], existing learning-based methods [26,30,37,40,46] are just trained on synthetic data before applying on real portraits. However, the domain gap between rendered images (from synthetic hair models) and real images has a great and negative impact on the quality of reconstructed results.…”

“…To narrow the domain gap between the synthetic data and real images, most existing methods [37,38,41,46] take 2D orientation map [23] as an intermediate representation between the input image and 3D hair model. However, this undirected 2D orientation map is ambiguous in growing direction and loses 3D hints given in the image.…”

“…This subjective measurement may lead to unfair evaluation and biased conclusion. NeuralHDHair [37] projects the growth direction of reconstructed 3D strands, and compares with the 2D orientation map filtered from real image. This is a noteworthy progress, but the extracted orientation map is noisy and inaccurate.…”

“…However, the hair models reconstructed by these methods tend to be coarse and over-smoothed, mainly due to the limited capacity of 3D neural network. To address this issue, Neural-HDHair [37] proposes a coarse-to-fine manner to obtain the high resolution 3D orientation fields and occupancy fields, enabling the GrowingNet to generate decent hair models.…”