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Projects: Algorithms & Architectures

Hyperbolic View Dependency for All-in-Focus Time of Flight Fields

  • We describe the hyperbolic view dependency in Time of Flight Fields
  • Our all-in-focus filter improves 3D fidelity and robustness to noise and saturation
  • We release a dataset of thirteen 15 x 15 time of flight field images

BuFF: Burst Feature Finder for Light-Constrained 3D Reconstruction

  • We introduce burst feature finder, a 2D + time feature detector and descriptor for 3D reconstruction
  • Finding features with well defined scale and apparent motion within a burst of frames
  • Approximate apparent feature motion under typical robotic platform dynamics, enabling critical refinements on hand-held burst imaging
  • More accurate camera pose estimates, matches and 3D points in low-SNR scenes

Light-Constrained Structure-from-Motion

  • We adapt burst imaging for 3D reconstruction in low light
  • Combining burst locally and feature-based methods over broad motions benefits from the strengths of each
  • Allows 3D reconstructions where conventional imaging fails
  • More accurate camera trajectory estimates, 3D reconstructions, and lower overall computational burden

Vision around Refractive Objects

  • A new kind of feature that exists in the patterns of light refracted through objects
  • Allows 3D reconstructions where SIFT / LiFF fail
  • More accurate camera trajectory estimates, 3D reconstructions in complex refractive scenes

LiFF Light Field Features Toolbox

  • SIFT-like features for light fields
  • Robust to occlusions, noise, and high-order light transport effects
  • Each feature has a well-defined depth / light field slope

Change Detection from Mobile Light Field Cameras

  • Closed-form change detection from moving cameras
  • Model-free handling of nonuniform apparent motion from 3D scenes
  • Handles failure modes from competing single-camera methods
  • Approach generalizes to simplifying other moving-camera problems

Volumetric Focus

  • A linear filter that focuses on a volume instead of a plane
  • Enhanced imaging in low light and through murky water and particulate
  • Derivation of the hypercone / hyperfan as the fundamental shape of the light field in the frequency domain

Light Field Depth-Velocity Filtering

  • A 5D light field + time filter that selects for depth and velocity
  • C. U. S. Edussooriya, D. G. Dansereau, L. T. Bruton, and P. Agathoklis, “Five-dimensional (5-D) depth-velocity filtering for enhancing moving objects in light field videos,” IEEE Transactions on Signal Processing (TSP), vol. 63, no. 8, pp. 2151–2163, April 2015. Available here.

Gradient-based depth estimation from light fields

  • Depth from local gradients
  • Simple ratio of differences, easily parallelized
  • D. G. Dansereau and L. T. Bruton, “Gradient-based depth estimation from 4D light fields,” in Intl. Symposium on Circuits and Systems (ISCAS), 2004, vol. 3, pp. 549–552. Available here.

Plenoptic flow for closed-form visual odometry

  • Generalization of 2D Lucas–Kanade optical flow to 4D light fields
  • Links camera motion and apparent motion via first-order light field derivatives
  • Solves for 6-degree-of-freedom camera motion in 3D scenes, without explicit depth models
  • D. G. Dansereau, I. Mahon, O. Pizarro, and S. B. Williams, “Plenoptic flow: Closed-form visual odometry for light field cameras,” in Intelligent Robots and Systems (IROS), 2011, pp. 4455–4462. Available here.
  • see also Ch.5 of D. G. Dansereau, “Plenoptic signal processing for robust vision in field robotics,” PhD thesis, Australian Centre for Field Robotics, School of Aerospace, Mechanical; Mechatronic Engineering, The University of Sydney, 2014. Available here.