human: Given a node-centered hypergraph: <hypergraph>, where nodes represent papers and hyperedges represent sets of papers co-cited by a source paper.

Details of the hypergraph:
Center node: "a variational approach to shape from shading under natural illumination"
  Abstract: A numerical solution to shape-from-shading under natural illumination is presented. It builds upon a generic PDE-based formulation which handles directional or spherical harmonics lighting, orthographic or perspective projection, and greylevel or multi-channel images. An augmented Lagrangian solver is proposed, which separates the global, nonlinear optimization problem into a sequence of simpler (either local or linear) ones. Real-world applications to shading-aware depth map denoising, refinement and completion are presented.

Connected through hyperedge HE-1 (induced by source paper "photometric depth super resolution"):
  with members:
    - "pixel2mesh generating 3d mesh models from single rgb images"
    - "cnn ps cnn based photometric stereo for general non convex surfaces"
    - "learning to predict indoor illumination from a single image"
    - "led based photometric stereo modeling calibration and numerical solution"
    - "variational methods for normal integration"
    - "neural face editing with intrinsic image disentangling"
    - "normal integration a survey"
    - "learning non lambertian object intrinsics across shapenet categories"

Question: Please tell me which class the center node belongs to. The 40 classes are: cs.NA(Numerical Analysis), cs.MM(Multimedia), cs.LO(Logic in Computer Science), cs.CY(Computers and Society), cs.CR(Cryptography and Security), cs.DC(Distributed, Parallel, and Cluster Computing), cs.HC(Human-Computer Interaction), cs.CE(Computational Engineering, Finance, and Science), cs.NI(Networking and Internet Architecture), cs.CC(Computational Complexity), cs.AI(Artificial Intelligence), cs.MA(Multiagent Systems), cs.GL(General Literature), cs.NE(Neural and Evolutionary Computing), cs.SC(Symbolic Computation), cs.AR(Hardware Architecture), cs.CV(Computer Vision and Pattern Recognition), cs.GR(Graphics), cs.ET(Emerging Technologies), cs.SY(Systems and Control), cs.CG(Computational Geometry), cs.OH(Other Computer Science), cs.PL(Programming Languages), cs.SE(Software Engineering), cs.LG(Machine Learning), cs.SD(Sound), cs.SI(Social and Information Networks), cs.RO(Robotics), cs.IT(Information Theory), cs.PF(Performance), cs.CL(Computation and Language), cs.IR(Information Retrieval), cs.MS(Mathematical Software), cs.FL(Formal Languages and Automata Theory), cs.DS(Data Structures and Algorithms), cs.OS(Operating Systems), cs.GT(Computer Science and Game Theory), cs.DB(Databases), cs.DL(Digital Libraries), cs.DM(Discrete Mathematics). Directly output the class name.

gpt: cs.CV(Computer Vision and Pattern Recognition)