CashFlow, A Visualization Framework for 3D Flow - Studierstube ...

Results5.7. Polygonal Surfaces & Textured SurfacesFigure 5.22 shows an example of a 2d histogram sharing the data with the heightfield on the right. Histograms are able to analyze scalar data from DataAccess node’s.Figure 5.22: CashFlow 2D Histogram5.7 Polygonal Surfaces & Textured SurfacesFigure 5.23 shows polygonal rendering of curvilinear grids. The left image containsthe rocket booster in yellow with an overlayed point rendering of grid points in the nextlayer. Right behind it the external Tank ins rendered in blue using flat–shading. Thegreen band visualizes the deformation of the curvilinear grid in axial direction enclosingthe space shuttle. The space shuttle is rendered twice, on one hand using Gouraud–shading[Gou71] in combination with a point rendering of the other half of the spaceshuttle. Unfortunately OpenGL still does not support Phong–shading[Pho73][BW86]although the necessary vertex normals are available. This limitation of OpenGL isbypassed using shaders in general.On the other hand using flat–shading on top of the first rendered shuttle. The rightimage in figure 5.23 shows the same scene from another viewing angle with differentrendering parameters. From top to bottom the first shuttle (top) is textured with adominant green PLIC texture. The middle rendering shows Gouraud–shading and agrid visualization for the right side of the shuttle. The grid visualization consists ofaxial lines rendered in blue and radial lines rendered in yellow. The illustration at thebottom is similar to the left image, except for the shading style used for the space shuttlein yellow. In the right image the space shuttle at the bottom is flat–shaded while in theleft image the lower space shuttle is rendered with Gouraud–shading. Figure 5.24 andfigure 5.25 show curvilinear grid visualizations enhancing the shape of the grids.117