Software lab 3-23-98

March 23, 1998 Design News

SOFTWARE LAB Reviews on tools of the trade

Tecplot eases graphing

Paris C. Altidis, Staff Engineer Borg Warner Automotive Inc.

The Windows version of Tecplot features a new user interface and a slew of features. Suitable for applications involving huge amounts of data, Tecplot can easily sort and plot with one of its 2- and 3-D graphics tools.

Because Tecplot has no way to generate raw data that need to be plotted, it is a graphing tool for users with advanced needs. Tecplot is being used in disciplines where the amount of data is more than you can generate on-the-fly. The data file needs to be of a specific format before it is imported into Tecplot. Tecplot can read standard ASCII, binary in 32- or 64-bit floating point, long and short integers, bytes, and bit data files. Tecplot does not support Hierarchical Data Format type for importing data with embedded text annotation and color images.

The data files have a distinct notation as to how the data are described. You can have up to three orders of data, with each order designating the number of parameters you have available. For a 2-D plot, your data can be of IJ order (Tecplot's Dimension designation) and for volumetric data your file will contain IJK ordered data. With the new tools, turning a volumetric representation into an XY plot is just a mouse click away.

Despite Tecplot's inability to create the data, it can manipulate it in a plethora of ways. You can change or create new data either explicitly or by using mathematical functions. Apart from the built-in intrinsic functions, you can mirror, scale, rotate, clip, or extract subsets of data. The list also includes special operators for finite differences, derivatives, or gradients. The data manipulation can be done for one zone or all of them simultaneously. You can also access your data-generating application from within Tecplot for further pre-plot data manipulation.

Tecplot can plot your data with any saved style sheet or use it for other datasets. Often, you may have to show multiple windows from the same dataset or multiple datasets. The plots can also be annotated with different variations of text in any angle and style, and geometric objects. These objects can also help you create word charts and 3-D geometries.

In essence, stylesheet and layout files are considered macro files. But Tecplot uses macros in a more subtle way, as it allows you to use nested loop sequence, IF THEN structures, or even logic statements that allow you to loop within the macro.

As soon as the mesh (the object of what you try to visualize your data on) is defined, your data can be displayed as contours, vectors, stream traces, or symbols. For more complicated cases, you can have your structure defined as part of your graph and superimpose the data on top of it. Support of DXF or IGES would have made the structure definition faster, but it is not included.

Tecplot can represent the core of volumetric datasets in several ways, such as slicing the volume by adding cutting planes in a parallel or intersection fashion at various zones. The data variables are then interpolated for each slice. Since you can define intersecting zones, you can define a block and remove it (or blank it) so that portions of the volumetric core become visible. New in this version is the addition of blanking using cylindrical coordinate systems.

Enhancements in Tecplot's macro language help you create output sequences of data plotting varying, for example, with respect to time. These sequences can then be played back with a supplied utility or using your VCR. Although the speed of animation is strictly a function of hardware, you still have the animation control to stop, play one frame at a time, or move forward or backward one frame.

The new enhancements make Tecplot a better solution for visualizing large sets of data and being productive within hours of use. It has myriad tools for technical data presentation, but a lack of OLE functionality prevents its use from within other Windows applications.