In the figure below we show the options available to the user to analyze an individual data set.
Standard visualization techniques such as tetrahedral dart vector glyphs are used to represent vector and scalar fields simultaneously; their direction and length correspond to the direction and magnitude of the vector field at that data point. The color, C, assigned to each vector glyph is determined by interpolating the field value of interest, s, over some range, [m_r,M_r], which can be dynamically selected by the user. That is, C = (M_r - s)/(M_r - m_r). If s=m_r, the color assigned to the vector glyph is blue; if s=M_r, the color assigned to the vector glyph is red. The extrema values, m_r and M_r, can be chosen in a number of different ways: by the individual data set extrema, m_d and M_d; by the global extrema over all the data sets, m_g and M_g, or by user-defined bounds, m_u and M_u. In addition, the user may manipulate the vector field glyphs by culling vectors whose corresponding scalar value falls outside the range [m_u,M_u] or by uniformly magnifying them for easier viewing.
In these figures, we show the use of the vector field glyphs for the three different fuel types under consideration: air, an air/O2 mix, and pure O2 (left to right, respectively) (see the motivating application). The color map is determined by the global range [m_g,M_g] for temperature. Blue indicates the coldest temperature among the three data sets, approximately 273 F in the molten aluminum in the air data set, and red indicates the hottest temperature, approximately 3050 F in the combustion space of the O2 data set. The four areas of high-speed flows are in the vicinity of the furnace burners. This series of images clearly shows that air fuel yields the coldest temperatures in the combustion space, averaging only about 1600 F, and therefore yields the poorest furnace efficiency. The temperatures corresponding to the O2 fuel are the hottest, with the air/O2 mix falling in between.
In addition to the static vector field glyphs, the user may choose to visualize the fluid flow in individual data sets by using animated streamlines, dynamic flow field movies, or interactively defined cutting planes. The streamlines and flow field movies may be colored by the scalar field of choice, but the range is constrained to [m_d,M_d]. The interactively defined cutting planes have the most flexible color maps, and the user may choose the ranges corresponding to any of the bounds defined above, [m_{d,g,u},M_{d,g,u}] or the cutting plane extrema, [m_c,M_c]. In addition, if the range [m_u,M_u] is used, data culling in the cutting plane also occurs; that is, data that falls outside the bounds are not drawn and appear as holes in the cutting plane.