Light field

About: Light field is a research topic. Over the lifetime, 5357 publications have been published within this topic receiving 87424 citations.

Light field transfer: global illumination between real and synthetic objects

Abstract: We present a novel image-based method for compositing real and synthetic objects in the same scene with a high degree of visual realism. Ours is the first technique to allow global illumination and near-field lighting effects between both real and synthetic objects at interactive rates, without needing a geometric and material model of the real scene. We achieve this by using a light field interface between real and synthetic components---thus, indirect illumination can be simulated using only two 4D light fields, one captured from and one projected onto the real scene. Multiple bounces of interreflections are obtained simply by iterating this approach. The interactivity of our technique enables its use with time-varying scenes, including dynamic objects. This is in sharp contrast to the alternative approach of using 6D or 8D light transport functions of real objects, which are very expensive in terms of acquisition and storage and hence not suitable for real-time applications. In our method, 4D radiance fields are simultaneously captured and projected by using a lens array, video camera, and digital projector. The method supports full global illumination with restricted object placement, and accommodates moderately specular materials. We implement a complete system and show several example scene compositions that demonstrate global illumination effects between dynamic real and synthetic objects. Our implementation requires a single point light source and dark background.

The Light Field Attachment: Turning a DSLR into a Light Field Camera Using a Low Budget Camera Ring

Abstract: We propose a concept for a lens attachment that turns a standard DSLR camera and lens into a light field camera. The attachment consists of eight low-resolution, low-quality side cameras arranged around the central high-quality SLR lens. Unlike most existing light field camera architectures, this design provides a high-quality 2D image mode, while simultaneously enabling a new high-quality light field mode with a large camera baseline but little added weight, cost, or bulk compared with the base DSLR camera. From an algorithmic point of view, the high-quality light field mode is made possible by a new light field super-resolution method that first improves the spatial resolution and image quality of the side cameras and then interpolates additional views as needed. At the heart of this process is a super-resolution method that we call iterative Patch- And Depth-based Synthesis (iPADS), which combines patch-based and depth-based synthesis in a novel fashion. Experimental results obtained for both real captured data and synthetic data confirm that our method achieves substantial improvements in super-resolution for side-view images as well as the high-quality and view-coherent rendering of dense and high-resolution light fields.

Efficient intra prediction scheme for light field image compression

Abstract: Interactive photo-realistic graphics can be rendered by using light field datasets. One way of capturing the dataset is by using light field cameras with microlens arrays. The captured images contain repetitive patterns resulted from adjacent mi-crolenses. These images don't resemble the appearance of a natural scene. This dissimilarity leads to problems in light field image compression by using traditional image and video encoders, which are optimized for natural images and video sequences. In this paper, we introduce the full inter-prediction scheme in HEVC into intra-prediction for the compression of light field images. The proposed scheme is capable of performing both unidirectional and bi-directional prediction within an image. The evaluation results show that above 3 dB quality improvements or above 50 percent bit-rate saving can be achieved in terms of BD-PSNR for the proposed scheme compared to the original HEVC intra-prediction for light field images.

Optical Sectioning Tomographic Reconstruction of Three-Dimensional Flame Temperature Distribution Using Single Light Field Camera

Abstract: The temperature measurement has great significance for the combustion diagnostics and the study of flame characteristics. In this paper, an optical sectioning tomographic (OST) technique for 3-D flame temperature measurement combined with light field imaging is proposed. First, the fundamental principle of light field OST is introduced in detail. Then, to determine the refocused depth, the point spread functions of the light field camera, and the relationship between the radiation intensity of flame and image gray value, the calibration works are carried out. Furthermore, the images of different sections of flame are acquired by the digital refocusing technology, and then the high-precision and real-time radiation intensity distribution of each section can be reconstructed using a tomographic reconstruction algorithm. Finally, in combination with the relationship between the image gray value and radiation intensity of flame, the 3-D flame temperature distribution can be calculated. The flame experiments of a candle and a single biomass particle in a fluidized bed under oxy-combustion conditions are performed to evaluate the light field OST system. Results show that the reconstructed results are in good agreement with the temperature distribution of the combustion flame. Compared with the traditional optical sectioning tomographic techniques, the light field OST has the advantages of simplicity of measurement system and fast response, and being suitable for 3-D temperature measurement of turbulent flame.

Magneto-optical beam splitter for atoms.

Abstract: We report an experimental demonstration of diffraction of ${\mathrm{He}}^{\mathrm{*}}$ atoms from a magneto-optical grating. The grating was produced by the interaction of three-level atoms with a light field of spatially varying polarization and a magnetic field. For a light shift matched to the Zeeman shift, a two-peaked diffraction pattern was observed, corresponding to a momentum splitting of 42\ensuremath{\Elzxh}k. The effect of changing the polarizations of the light field was investigated. The diffraction from the magneto-optical grating is compared directly with the diffraction of two-level atoms from a standing light wave and it is shown, that the magneto-optical interaction leads to more efficient coupling into high order momentum states.