  We propose a method for synthesizing photo-realistic digital avatars from
only one portrait as the reference. Given a portrait, our method synthesizes a
coarse talking head video using driving keypoints features. And with the coarse
video, our method synthesizes a coarse talking head avatar with a deforming
neural radiance field. With rendered images of the coarse avatar, our method
updates the low-quality images with a blind face restoration model. With
updated images, we retrain the avatar for higher quality. After several
iterations, our method can synthesize a photo-realistic animatable 3D neural
head avatar. The motivation of our method is deformable neural radiance field
can eliminate the unnatural distortion caused by the image2video method. Our
method outperforms state-of-the-art methods in quantitative and qualitative
studies on various subjects.
