Practical tutorial 1


Scalar and Vector Visualization with VTK


The goal of the practical part of this tutorial is to visualize a dataset which represents the blood flow in the carotid vessels in the human head. The data

The dataset consists of a file with a structured points dataset in VTK format. The data contains two type of attributes: The first attribute is a scalar value for point in the dataset. This scalar value encodes the speed of the blood flow. The second attribute is a vector for every point in the dataset which encodes the direction AND speed of the blood flow. In this exercise you should use both the scalar and vector attributes.

To get started


You have the following tasks:

  1. Read the data into a VTK program. You can use the class vtkStucturedPoints to read the file.
  2. Generate a rendering of the blood vessels. You can do this by extracting an isosurface of all points where the speed (i.e. the scalar value) of the blood flow is larger than 200. In order to extract an isosurface you can use the class vtkContourFilter.
  3. Visualize the blood flow using glyphs. In this task you will have to draw arrows to represent the orientation and speed of the blood flow. In order to make the visualization less cluttered it makes sense to only draw arrows in regions where the speed of the blood flow is above a threshold. You can use the class vtkThresholdPoints to threshold your dataset. To draw the arrows use the classes vtkArrowSource and vtkGlyph3D.
  4. Visualize the blood flow using streamlines. This task is similar to the previous task except for the fact that you should visualize the vector field using streamlines rather than the glyphs. The necessary VTK classes for this are vtkStreamLine and vtkRungeKutta4. Moreover you will need to specify from where to start the streamline visualization. Using the class vtkPointSource it is possible to generate a point cloud around a certain location. This enables the tracking of multiple streamlines.


Hints:


  • You can download the dataset from here
  • A good starting point for the streamline tracking is (131, 112, 20)
  • Look at the examples in /vol/vtk/vtk-5.0/src/Examples