Abstract
In the field of computational fluid dynamics (CFD), the upwind finite volume method (FVM) is widely applied to solve 3D flows with discontinuity phenomena (e.g., shock waves). It produces unstructured data at the center of each cell (cell-centered data) with the flow discontinuity constraint on the inner-face between face-neighboring cells. For visualization, existing approaches with interpolation usually pre-extrapolate cell-centered data into cell-vertexed data (data values given at cell vertices) and only handle cell-vertexed data during actual rendering, which unconsciously depress the rendering accuracy and violate the discontinuity constraint. In this paper, we propose a novel method to visualize cell-centered data directly avoiding extrapolation and keep the discontinuity in the rendering data on the framework of multi-pass raycasting. During resampling, the field is reconstructed using the original cell-centered data value and the cell-gradient estimated by Green–Gauss theorem. To keep the discontinuity, we reconstruct the field at an inner-face resampled point using both the face-adjacencies and get two discontinuous field values. Then the field is obtained by computing Roe-average of the two. The analysis and experiments demonstrate that our approach gains a high-accuracy reconstruction and leads to a high-quality image.
Similar content being viewed by others
References
Barth, T.J., Jespersen, D.C.: The design and application of upwind schemes on unstructured meshes. In: 27th Aerospace Sciences Meeting, AIAA-89-0366 (1989)
Frink, N.T.: Upwind scheme for solving the Euler equations on unstructured tetrahedral meshes. AIAA J. 30(1), 70–77 (1992)
Godunov, S.K.: A difference scheme for numerical computation discontinuous solution of hydrodynamic equations. Mat. Sb. 47(3), 271–306 (1959)
Van Leer, B.: Towards the ultimate conservative difference scheme. V. A second-order sequel to Godunov’s method. J. Comput. Phys. 32(1), 101–126 (1979)
Frink, N.T., Parikh, P., Pirzadeh, S.: A fast upwind solver for the Euler equations on three-dimensional unstructured meshes. Technical Report, AIAA-91-0102 (1991)
Roe, P.L.: Approximate Riemann solvers, parameter vectors, and difference schemes. J. Comput. Phys. 43(2), 357–372 (1981)
Weiler, M., Kraus, M., Merz, M., Ertl, T.: Hardware-based ray casting for tetrahedral meshes. In: Proceedings of the 14th IEEE Visualization 2003, pp. 333–340
Bernardon, F.F., Pagot, C.A., Comba, J.L.D., Silva, C.T.: Gpu-based tiled raycasting using depth peeling. J. Graph. Tools 11(4), 1–16 (2006)
Silva, C.T., Comba, J.L.D., Callahan, S.P., Bernardon, F.F.: A survey of gpu-based volume rendering of unstructured grids. Braz. J. Theor. Appl. Comput. 12(2), 9–29 (2005)
McLoughlin, T., Laramee, R.S., Peikert, R., Post, F., Chen, M.: Over two decades of integration-based, geometric flow visualization. Comput. Graph. Forum (2010, to appear)
Muigg, P., Hadwiger, M., Doleisch, H., Hauser, H.: Scalable hybrid unstructured and structured grid raycasting. IEEE Trans. Vis. Comput. Graph. 13(6), 1592–1599 (2007)
Max, N., Correa, C., Muelder, C., Yan, S., Chen, C.-K., Ma, K.-L.: Flow visualization in science and mathematics. J. Phys. 180(1), 012087–012096 (2009)
Schneider, P.J., Eberly, D.H.: Geometric Tools for Computer Graphics, pp. 9–16. Morgan Kaufmann, San Mateo (2003)
Garrity, M.P.: Raytracing irregular volume data. In: Proceedings of the 1990 Workshop on Volume Visualization, vol. 24(5), pp. 35–40 (1990)
Correa, C.D., Hero, R., Ma, K.-L.: A comparison of gradient estimation for volume rendering on unstructured meshes. IEEE Trans. Vis. Comput. Graph. (2009)
Mitchell, C.R.: Improved reconstruction schemes for the Navier-Stokes equations on unstructured meshes. In 32nd AIAA Aerospace Sciences Meeting and Exhibit, AIAA-94-0642 (1994)
Mammen, A.: Transparency and antialiasing algorithms implemented with the virtual pixel maps technique. IEEE Comput. Graph. Appl. 9(4), 43–55 (1989)
Rottger, S., Kraus, M., Ertl, T.: Hardware-accelerated volume and isosurface rendering based on cell-projection. In: Proceedings of IEEE Visualization 2000, pp. 109–116
Bunyk, P., Kaufman, A., Silva, C.T.: Simple, fast, and robust ray casting of irregular grids. In: Proceedings of IEEE Visualization 1997, pp. 30–36
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Ma, Q., Xu, H., Zeng, L. et al. Direct raycasting of unstructured cell-centered data by discontinuity Roe-average computation. Vis Comput 26, 1049–1059 (2010). https://doi.org/10.1007/s00371-010-0447-9
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00371-010-0447-9