93 research outputs found
Accurate Light Field Depth Estimation with Superpixel Regularization over Partially Occluded Regions
Depth estimation is a fundamental problem for light field photography
applications. Numerous methods have been proposed in recent years, which either
focus on crafting cost terms for more robust matching, or on analyzing the
geometry of scene structures embedded in the epipolar-plane images. Significant
improvements have been made in terms of overall depth estimation error;
however, current state-of-the-art methods still show limitations in handling
intricate occluding structures and complex scenes with multiple occlusions. To
address these challenging issues, we propose a very effective depth estimation
framework which focuses on regularizing the initial label confidence map and
edge strength weights. Specifically, we first detect partially occluded
boundary regions (POBR) via superpixel based regularization. Series of
shrinkage/reinforcement operations are then applied on the label confidence map
and edge strength weights over the POBR. We show that after weight
manipulations, even a low-complexity weighted least squares model can produce
much better depth estimation than state-of-the-art methods in terms of average
disparity error rate, occlusion boundary precision-recall rate, and the
preservation of intricate visual features
Optical modelling of accommodative light field display system and prediction of human eye responses
The spatio-angular resolution of a light field (LF) display is a crucial
factor for delivering adequate spatial image quality and eliciting an
accommodation response. Previous studies have modelled retinal image formation
with an LF display and evaluated whether accommodation would be evoked
correctly. The models were mostly based on ray-tracing and a schematic eye
model, which pose computational complexity and inaccurately represent the human
eye population's behaviour. We propose an efficient wave-optics-based framework
to model the human eye and a general LF display. With the model, we simulated
the retinal point spread function (PSF) of a point rendered by an LF display at
various depths to characterise the retinal image quality. Additionally,
accommodation responses to rendered LF images were estimated by computing the
visual Strehl ratio based on the optical transfer function (VSOTF) from the
PSFs. We assumed an ideal LF display that had an infinite spatial resolution
and was free from optical aberrations in the simulation. We tested images
rendered at 0--4 dioptres of depths having angular resolutions of up to 4x4
viewpoints within a pupil. The simulation predicted small and constant
accommodation errors, which contradict the findings of previous studies. An
evaluation of the optical resolution of the rendered retinal image suggested a
trade-off between the maximum resolution achievable and the depth range of a
rendered image where in-focus resolution is kept high. The proposed framework
can be used to evaluate the upper bound of the optical performance of an LF
display for realistically aberrated eyes, which may help to find an optimal
spatio-angular resolution required to render a high quality 3D scene.Comment: 24 pages, 12 figures, submitted to Optics Expres
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