Analytical Ray Casting

I had an interesting request come through last week regarding analyzing the maximum value along a particular direction. The user desired this information as a form of comparison against experimental information gathered. In this instance, the user really wanted to define a plane as a start point, then move along a direction from this plane, and register what the maximum value was… and plot that back on the surface as some type of filled contour. The user also wanted to limit the length of this survey, so that they could determine the maximum within X units from the originating plane.

EnSight’s built in “Radiograph_mesh” and “Radiograph_grid” were first looked at, as they return an integral along a ray cast from a surface. This was useful, however they needed the maximum value (rather than integral), and wanted to control the length of the ray (rather than infinite), as they needed to compare to experimental data.

So, we already had a “Streamline Analysis” tool which analyzed streamlines, and returned various analytical information about the streamlines (scalar max being one of them). This tool analyzes each streamline in turn, and creates new scalar fields like distance traveled, time traveled, normalized scalar, maximum scalar. If you then combine this tool with a “Fixed” vector field, rather than a spatial varying velocity vector field, you can in effect cast “rays” along a particular direction and then analyze the values along each streamline.

Here is an example of that output, using a simplified exhaust manifold model.

Example of Ray Casting and Analysis of Max value along ray.

Example of Ray Casting and Analysis of Max value along ray.


The image on the left indicates the maximum value of temperature experienced a direction specified (this case normal to the clip), for a distance of 0.2 units.
You can find more information by watching a short video/audio tutorial here :



2 thoughts on “Analytical Ray Casting

  1. An alternative to this tool (if the user doesn’t need to control the ray length) uses an environmental variable that you can set in 10.1 to find the max and the min along a radiograph rather than just the integral.

    set the environmental variable ENSIGHT_RADIOGRAPH_OPTION
    set to 0 to integrate the ray (this is the default if no environmental variable)
    set to 1 finds min along ray
    set to 2 finds max along ray

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