Layered Lightfields for Occlusion Handling in Medical Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional lightfield rendering techniques struggle with occlusion, preventing cameras from moving inside or through objects, such as in medical imaging applications like colonoscopy, due to the convex hull of the object occluding interior views.
Innovation Solution
The method employs layered lightfields, where multiple lightfields are generated for different depths and surfaces, allowing camera positions within the convex hull by selecting appropriate lightfields based on depth information, enabling rendering from within concave regions and through objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If standard lightfield rendering is used, then interactivity is achieved, but camera positions are restricted to outside the convex hull of the object due to occlusion
Solution Approach 1:
The lightfield data is segmented into multiple layers corresponding to different depth ranges or isosurfaces. Each layer contains lightfield information for a specific depth interval, allowing the system to selectively composite layers based on camera position and desired visibility, thereby enabling views from within the convex hull that would otherwise be occluded.
Solution Approach 2:
The patent introduces a depth layer dimension to the traditional lightfield representation. By organizing lightfield data into multiple depth layers and using per-pixel depth values, the system adds a dimensional organization that enables selective visibility control, allowing cameras to virtually move into concave regions and through objects without being constrained by the convex hull occlusion.
2Manufacturing precision
If volume rendering with Monte-Carlo sampling is used for high quality, then image quality is improved, but rendering speed decreases making interactivity difficult
Solution Approach 1:
The patent performs preliminary rendering to pre-compute lightfield data for multiple camera positions and depth layers before runtime. This pre-computation stores radiance and orientation information in an organized layered structure, enabling fast interactive rendering by simply compositing pre-rendered layers rather than performing expensive Monte-Carlo sampling during interaction.
Solution Approach 2:
The system dynamically composites static pre-rendered lightfield layers based on runtime camera position and viewing parameters. This dynamic composition of pre-computed layers provides both high image quality (inherited from careful pre-rendering) and fast interactivity (from avoiding repeated expensive sampling), resolving the contradiction between quality and speed.
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
For occlusion handing in lightfield rendering, layered lightfields are created. Rather than use one lightfield for one camera position and orientation, multiple lightfields representing different depths or surfaces at different depths relative to that camera position and orientation are created. By using layered lightfields for the various camera positions and orientations, the camera may be located within the convex hull or scanned object. The depths of the layers are used to select the lightfields for a given camera position and location.