Attenuation-Based 3D Display Using Stacked LCDs
Introduction
Unlike traditional 2D displays, attenuation-based 3D displays enable the accurate, high-resolution depiction of motion parallax, occlusion, translucency, and specularity. We have implemented iterative tomographic reconstruction for image synthesis on a stack of spatial light modulators (multiple low-cost iPad LCDs). We illuminate these volumetric attenuators with a backlight to recreate a 4D target light field. Although five-layer decomposition generates the optimal tomographic reconstruction, our two-layer display costs less than $100 and requires less computation
Background
Additive Volumetric Displays
Printed Transparencies
Integral Imaging
Parallax Barriers
Multi-Layer and Tensor Displays
Methods
Light Field Acquisition
Layered Attenuation-based Displays
Tomographic Approximation We implemented the computed tomography techniques decsribed in “Layered 3D” by G. Wetzstein, D. Lanman, W. Heidrich, R. Raskar (SIGGRAPH 2011) to produce two 2048x1536 reconstructed images from many precomputed views of the light field, spanning a 20-degree FOV. We solve these layer decompositions ahead of time, and paint them as static images to the LCDs.
We designed an enclosure such that the stack of LCDs (2048x1536, 9.7”, IPS 60Hz, iPad 3) would be well-fastened and their driver circuitry well-hidden. In this intitial prototype, we attached the front LCD with adhesive so that we could manually adjust the display for approximate pixel alignment.
Results
Limitations: • Light Attenuation • Limited Field of View • Temporal Multiplexing Compute • Pixel Alignment • Color Crosstalk
Performance: • High Contrast Halo Artifacts • Depth of Field • Resolution • PSNR
Conclusions
Improvements: • Dynamic Rendering • High-Refresh Rate (>144Hz) • Three Layer Display • Face-Tracking (with OpenCV)
Appendix I
[1] G. Wetzstein, D. Lanman, W. Heidrich, R. Raskar. Layered 3D: Tomographic Image Synthesis for Attenuation-based Light Field and High Dynamic Range Displays. Proc. of SIGGRAPH 2011 (ACM Transactions on Graphics 30, 4), 2011.
[2] G. Wetzstein, D. Lanman, D. Gutierrez, M. Hirsch. Computational Displays. ACM SIGGRAPH 2012 Course, 2012.
Matlab Implementation of Tomographic Light Field Synthesis
Real-Time Implementation of Tomographic Light Field Synthesis