Researchers from IT4Innovations National Supercomputing Center have developed an innovative methodology for visualising large-scale data from computational fluid dynamics (CFD) simulations through volume rendering and advanced visualisation tools. This new method enables fast, interactive, and photorealistic data visualisation, which greatly simplifies data analysis. In developing the method, the researchers harnessed the power of the Karolina supercomputer.
CFD simulations are highly intensive in computational demands and often generate huge terabytes to petabytes of resulting data. Efficient processing of this data is crucial for fast and correct analysis of the results. Especially for unstructured meshes, post-processing is extremely computationaly and memory demanding. Currently available tools cannot efficiently process large, time-dependent unstructured data in a reasonable time.
Markéta Faltýnková, Ondřej Meca, Tomáš Brzobohatý, Lubomír Říha, Milan Jaroš, and Petr Strakoš from IT4Innovations have developed a new workflow to process data that allows the re-sampling of hundreds of time steps on an unstructured mesh with one billion cells (tens of terabytes of data) to a sparse regular grid with a density of 11 billion voxels (3D blocks) in minutes. This process uses thousands of processor cores and advanced algorithms for efficient data preparation, which is a prerequisite for the subsequent interactive visualisation.
The whole workflow consists of five key steps. First, data is loaded into memory in parallel to ensure fast upload of large data sets. The data is then evenly distributed across the available computational resources, optimising hardware utilisation, and speeding up processing. Unstructured data is then transformed into a regular grid (voxelisation), which simplifies subsequent processing. After resampling, the data is stored in OpenVDB format, the industry standard for computer graphics. Finally, the data is prepared for high-fidelity visualisation using Blender to create visually attractive and detailed output for analysis and presentation.
A unique feature of the developed solution is the GPU-accelerated interactive display of time-dependent simulations through volume rendering using a path tracing renderer. The volumetric representation of simulated quantities allows for efficient interactive exploration of the phenomena in both space and time interactively.
This new methodology for visualising large-scale data has been validated on specific simulations, such as a commercial aircraft. It took 37 minutes to prepare a one billion cell CFD simulation with 512 time steps (34 TB of data) for an interactive volumetric rendering with 11 billion voxels. This procedure outperforms current visualisation techniques and brings a new level of voxelisation scalability.
The method, tested on the Karolina supercomputer in Ostrava, is an efficient tool for post-processing and visualising large-scale CFD data, allowing researchers and engineers to analyse and visualise simulations faster, even for models with billions of cells. In the future, the research team will focus on implementing a hierarchical approach to reduce the memory demand while maintaining the visual quality of the output, and on further data reduction using neural networks.
Scientific paper
Workflow for high-quality visualisation of large-scale CFD simulations by volume rendering
https://doi.org/10.1016/j.advengsoft.2024.103822
This research was supported by the REFRESH project.
