Farthest Point Seeding for Placement of Streamlines


This package contains a running on windows implementation demo of the algorithm described in [MAD2005] (published in VISUALIZATION 2005), and a data set. It will be available as CGAL Package in the next release.
 
snapshot
Download here .
 

Input format (2D Vector field *.vec)

 

The input files are in ASCII format and contains the following fields :

  • Number of columns in the grid (unsigned integer).
  • Number of rows in the grid (unsigned integer).
  • The values of the vector field line by line (2 float values).
 
Example : 
70 70
-0.997971 -0.0636665
-0.999978 -0.00668849
-0.998783 0.0493141
-0.994606 0.103726

...

 

Description
 

Here is a brief description of the main functionalities of the demo :
  • Load a vector field in the specified format using File->open menu.
  • Adjust the parameters of the algorithm using  Streamlines->options :
    • Separating distance :
 specify the separating distance (a ratio of the image width).
    • Saturation ratio :
 the integration step is stopped when the domain contains no empy circle with radius (Separating distance*Saturation ratio)
    • Sampling step
 this parameter defines how much points are inserted in the triangulation.
    • Integration step
 the integration step used to generate the streamlines.
    • Vector frame size
 the size of the visualization grid.
  • Generate a placement of streamlines using Streamlines->Place. 
 

Step by step generation

 

To visualize the different algorithm steps, you can process as follows:

    • Streamlines->First Streamline

To generate the first streamline.

    • Streamlines->One Streamline
To generate the next streamline.
    • Streamlines->N Streamlines
To generate the next ten streamlines.
    • Streamlines->Resume
 Te resume the whole placement.
 

More options

 
    • Streamlines->clear

Clear all. The user has to load a new field.

    • Streamlines->Save placement ->Save as stl
Save the placement in an ASCII.
    • Streamlines->Save placement->Save as eps (without tapering)
 Save the placement in an eps file.
    • Streamlines->Save placement->Save as eps (with tapering)
Save the placement in an eps file using the tapering effect.