Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Shape and Spatially-Varying Reflectance Estimation From Virtual
  Exemplars   This paper addresses the problem of estimating the shape of objects that
exhibit spatially-varying reflectance. We assume that multiple images of the
object are obtained under a fixed view-point and varying illumination, i.e.,
the setting of photometric stereo. At the core of our techniques is the
assumption that the BRDF at each pixel lies in the non-negative span of a known
BRDF dictionary.This assumption enables a per-pixel surface normal and BRDF
estimation framework that is computationally tractable and requires no
initialization in spite of the underlying problem being non-convex. Our
estimation framework first solves for the surface normal at each pixel using a
variant of example-based photometric stereo. We design an efficient multi-scale
search strategy for estimating the surface normal and subsequently, refine this
estimate using a gradient descent procedure. Given the surface normal estimate,
we solve for the spatially-varying BRDF by constraining the BRDF at each pixel
to be in the span of the BRDF dictionary, here, we use additional priors to
further regularize the solution. A hallmark of our approach is that it does not
require iterative optimization techniques nor the need for careful
initialization, both of which are endemic to most state-of-the-art techniques.
We showcase the performance of our technique on a wide range of simulated and
real scenes where we outperform competing methods.

20
The categories of this paper are: acc-phys
23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
7
The categories of this paper are: hep-th
15
The categories of this paper are: nucl-ex
21
The categories of this paper are: adap-org
6
The categories of this paper are: astro-ph
33
The categories of this paper are: plasm-ph
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
18
The categories of this paper are: econ
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
35
The categories of this paper are: mtrl-th
17
The categories of this paper are: q-fin