Volume Rendering

Volume Rendering provides a new visualization technique within EnSight.  This new method does not create polygons like clip planes or isosurfaces, instead it creates pixel-accurate fog or mist-like rendering of the model or part based on a “transfer function”.


Editing the Transfer function is reached through the “Palette” button on the Color Dialog.

The “transfer function” is the yellow line whose profile is controlled by the “knots” or black points.

This “transfer function” would produce an image like this in the Cube demo model.  Notice only a single area of emphasis, the blue haze or fog which corresponds to the single area under the yellow curve in the transfer function above.  The Cube Volume example model has a default flat transfer function and the resulting image looks hazy and not very useful.

Let’s adjust the transfer function now to one which has one peak under the knots.  To give a single opaque-ish area. And lets remove the blue fog or haze.

This “transfer function” would produce an image like this (above) in the Cube demo model.

Now lets go further and choose multiple areas of interest.

Notice now 4 areas of emphasis, the blue haze or fog , and the two interior regions, one yellow and one green.  Its now clearer which side the flow is coming from and which side is the exit.


So volume rendering is useful for seeing fluid, temperature, and other 3D domains, particularly complex ones.

Instead of creating 4 isosurfaces of a variable at 10%, 20%, 50%, and 80% for example just use volume rendering and place emphasis on areas corresponding to the above 4 places of interest.   You will be able to easily adjust those areas of interest both the specific area, for example 10%, but also adjust the transparency of the 4 places of interest so that you can see them all at the same time or with differing amounts of emphasis.

Is Volume Rendering new in EnSight 10?  No, not entirely.  We introduced Volume Rendering in EnSight 9.

EnSight 9 Volume Rendering was:

  • Slow
  • Precise
  • Consumed vast amounts of memory
  • Unstructured architecture

EnSight 10 Volume Rendering is:

  • Fast
  • Mapped rather than precise
  • Efficient with memory
  • Structured architecture
  • Flexible on precision
EnSight 10 retains the ability to use EnSight 9 volume rendering if you require its unique precision.  In most cases EnSight 10 volume rendering advantages are so great that we think most customers will want to use it.  EnSight 10 Volume Rendering is mapped onto a structured grid and you can choose the resolution you need for that mapping.
If your data is already structured then you don’t need to do anything.  If your data is unstructured then you’ll need to create a new structured volume on which to map your original data and apply the volume rendering.  The volume is very efficient and EnSight can better leverage the computer hardware with a structured volume, so this method is strongly encouraged over using EnSight 9 Volume Rendering which is more precise and saves a step for the user, but is much less memory efficient.
For more information about Volume Rendering in general, see Wikipedia as an example.
Tutorials for Volume Rendering: