Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: 4-D Scene Alignment in Surveillance Video   Designing robust activity detectors for fixed camera surveillance video
requires knowledge of the 3-D scene. This paper presents an automatic camera
calibration process that provides a mechanism to reason about the spatial
proximity between objects at different times. It combines a CNN-based camera
pose estimator with a vertical scale provided by pedestrian observations to
establish the 4-D scene geometry. Unlike some previous methods, the people do
not need to be tracked nor do the head and feet need to be explicitly detected.
It is robust to individual height variations and camera parameter estimation
errors.

17
The categories of this paper are: q-fin
14
The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
15
The categories of this paper are: nucl-ex
3
The categories of this paper are: physics
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
5
The categories of this paper are: gr-qc
7
The categories of this paper are: hep-th
2
The categories of this paper are: math
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con