  We introduce a normal-based bas-relief generation and stylization method
which is motivated by the recent advancement in this topic. Creating bas-relief
from normal images has successfully facilitated bas-relief modeling in image
space. However, the use of normal images in previous work is often restricted
to certain type of operations only. This paper is intended to extend
normal-based methods and construct bas-reliefs from normal images in a
versatile way. Our method can not only generate a new normal image by combining
various frequencies of existing normal images and details transferring, but
also build bas-reliefs from a single RGB image and its edge-based sketch image.
In addition, we introduce an auxiliary function to represent a smooth base
surface and generate a layered global shape. To integrate above considerations
into our framework, we formulate the bas- relief generation as a variational
problem which can be solved by a screened Poisson equation. Some advantages of
our method are that it expands the bas-relief shape space and generates
diversified styles of results, and that it is capable of transferring details
from one region to other regions. Our method is easy to implement, and produces
good-quality bas-relief models. We experiment our method on a range of normal
images and it compares favorably to other popular classic and state-of-the-art
methods.
