Interactive Focus+Context Rendering for Hexahedral Mesh Inspection

TL;DR

This paper introduces an advanced GPU-based focus+context rendering technique for hexahedral mesh inspection, enabling interactive visualization that highlights specific regions while preserving global structure, improving clarity and usability.

Contribution

It presents a novel GPU shader method combining edge, face, and volumetric rendering with a sheet-based level-of-detail hierarchy for seamless focus+context visualization.

Findings

Achieves interactive frame rates for large meshes.

Provides smooth transition between focus and context views.

Enhances mesh inspection clarity and user interaction.

Abstract

The visual inspection of a hexahedral mesh with respect to element quality is difficult due to clutter and occlusions that are produced when rendering all element faces or their edges simultaneously. Current approaches overcome this problem by using focus on specific elements that are then rendered opaque, and carving away all elements occluding their view. In this work, we make use of advanced GPU shader functionality to generate a focus+context rendering that highlights the elements in a selected region and simultaneously conveys the global mesh structure in the surrounding. To achieve this, we propose a gradual transition from edge-based focus rendering to volumetric context rendering, by combining fragment shader-based edge and face rendering with per-pixel fragment lists. A fragment shader smoothly transitions between wireframe and face-based rendering, including focus-dependent rendering style and depth-dependent edge thickness and halos, and per-pixel fragment lists are used to blend fragments in correct visibility order. To maintain the global mesh structure in the context regions, we propose a new method to construct a sheet-based level-of-detail hierarchy and smoothly blend it with volumetric information. The user guides the exploration process by moving a lens-like hotspot. Since all operations are performed on the GPU, interactive frame rates are achieved even for large meshes.