This Stream Flow Visualization Tool supports drawing of arrow plots and streamlines out of Stream Flow Data.

The techniques used by this program, to draw evenly spaced streamlines is described in an article by Bruno Jobard and Wilfrid Lefer called 'Creating Evenly-Spaced Streamlines of Arbitary Density' and can be found at http://www-lil.univ-littoral.fr/~jobard/Research/Publications/EGW-ViSC97/ViSC97.abstract.html.

The algorithms and mechanisms for drawing arrow plots and 'normal' streamlines are taken from the script of the lecture "Visualisation" at The Institute of Computer Graphics - Vienna University of Technology held by Helwig Hauser.

Fileformat of the StreamVisio:

The file format of this Stream Flow Visualization Tool is a simple one. The format stores the geometry in a file with a .gri extention and each timestep of the set in file with the same basename but with an extention consisting of the number of the timestep and a .dat extention. The gridfile consists of a 40 byte ascii header and the (binairy) position data. 

The header holds the dimensions of the set, the additional number of sets, the number of time steps and the timestep between two timesteps.

This version of StreamVisio only supports one timestep, so additional timesteps will be ignored during load time.

The geometry is organized as a 3D array of positions each consisting of 3 floats (=4 bytes): (px,py,pz).

The data files are organized equally with the exception that the number of floats depends on the number of additional datasets.

Note: a data set from a small-endigian machine is expected.
 

Configuration of the StreamVisio:

The - StreamVisio - Stream Flow Visualization Tool is highly configurable.

The user can chose, either to draw an arrow plot or to draw streamlines of the loaded data.

• Arrow Plot:

The arrows will be plotted at the specified grid size and with the selected color. Normally the length of the arrows indicate the strength of the flow stream, but the length of all the arrows can be normalized by checking the 'Normalized Vector' - button.

Additional arrows can be inserted in the plot by clicking on the image. The arrow will be calculated by using the current settings and will be drawn at the choosen position.
 

• Streamlines:

The Streamlines will be generated either using the Euler- or the Runge-Kutta (2nd order) integration algorithm. The step size for the integration mechanism can be configured by the 'Delta-T' input field. This input field accepts values from 1 to 20, where 1 is a small and 20 a large step size.

By checking the 'Evenly Spaced' - button evenly spaced streamlines will be generated. For this calculations the 'd_sep' and 'd_test' input field are used. These fields represent the same named characteristic variables in the article 'Creating Evenly-Spaced Streamlines of Arbitary Density' by Bruno Jobard and Wilfrid Lefer.
 

By checking the 'Background' - button the drawn background can be modified. Either the strength of the flow, the pressure or the perpendicular vorticity can be drawn. If the 'Background' - button is not checked, a black background will be drawn. The legend under the image shows the color palette used when drawing the background.

The color, which is used to draw the arrows or the streamlines, can be changed by clicking on the colored rectangle beside the 'Color' - label.

The grid size is used when drawing an arrow plot or the normal streamlines (not evenly spaced). The grid size can be configured from 8 to 128 - the spin buttons beside, change the grid size by 2^n.

• First and Final Version of DVR is 1.0 and can be downloaded here.
• If you you want to look at the Source Code, please contact me!!

• This Version of a "Stream Flow Visualization" Tool - StreamVisio - was developed by G. Matzka as part of the Course "Visualisation" at The Institute of Computer Graphics - Vienna University of Technology