Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gravitational Lensing by Spinning Black Holes in Astrophysics, and in
  the Movie Interstellar   Interstellar is the first Hollywood movie to attempt depicting a black hole
as it would actually be seen by somebody nearby. For this we developed a code
called DNGR (Double Negative Gravitational Renderer) to solve the equations for
ray-bundle (light-beam) propagation through the curved spacetime of a spinning
(Kerr) black hole, and to render IMAX-quality, rapidly changing images. Our
ray-bundle techniques were crucial for achieving IMAX-quality smoothness
without flickering.
  This paper has four purposes: (i) To describe DNGR for physicists and CGI
practitioners . (ii) To present the equations we use, when the camera is in
arbitrary motion at an arbitrary location near a Kerr black hole, for mapping
light sources to camera images via elliptical ray bundles. (iii) To describe
new insights, from DNGR, into gravitational lensing when the camera is near the
spinning black hole, rather than far away as in almost all prior studies. (iv)
To describe how the images of the black hole Gargantua and its accretion disk,
in the movie \emph{Interstellar}, were generated with DNGR. There are no new
astrophysical insights in this accretion-disk section of the paper, but disk
novices may find it pedagogically interesting, and movie buffs may find its
discussions of Interstellar interesting.

32
The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
18
The categories of this paper are: econ
14
The categories of this paper are: math-ph
15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an
20
The categories of this paper are: acc-phys
36
The categories of this paper are: cmp-lg
12
The categories of this paper are: nucl-th