A Beginners Guide to SPEOS Simulation – Super Bowl Party Edition

As we ease out of winter and move into spring, there is a lot to look forward to. Flowers blooming, warmer days, and America’s favorite pseudo-holiday: The Super Bowl. What’s not to like? It’s a day filled with food, fun, and ample beer. But there’s always one guy who takes things a little too far. Let’s call him Chad. You’ve probably seen Chad in action before… after having a few too many drinks, he’s all riled up at his team’s latest bad play and won’t stop screaming two feet in front of the TV screen. 

I know how this feels far too well. The good news is, I’m here to help. With this simulation, we’ll model exactly where to position yourself to still catch the game, even with Chad trying his best to cause a disruption. To do this, I will walk you through a beginner’s guide on how to set up a Super Bowl party in Ansys SPEOS with a display source, ambient light source, and human eye sensors in an inverse simulation.  

To begin I will lay out some keywords or areas in Ansys SPEOS that I will be mentioning in the guide.

• Structure Tree: This is where all your objects, components, and origins will sit.
• Simulation Panel: This is where anything you add to the optics side of SPEOS will be.
• Definition Panel: This is where all the optical parameters can be specified.

Figure 1. Structure Tree, Simulation Panel, Definition Panel

CAD Layout

Set up your structures. It is all done within Ansys Space Claim (as SPEOS lives in it). To set up this simulation we can add a TV, couches, and people. When duplicating the people or objects, it is important to make sure that they are all independent from the original structure. To make things simpler it is recommended to rename all the objects in the structure tree for smooth sailing down the line. Once the CAD is set up, we can start adding optical properties.

Material

The first step is to make sure every object in your structure tree has an optical material defined. You will have errors and problems simulating if this is not done correctly. Adding materials is very simple using the SPEOS optical library.

The SPEOS optical library is available for download in the Ansys customer download center under “add-on packages”.

Figure 2. Downloads site from Ansys -- download optical libraries in the add on section

To add material to an object by following the steps below -- in the image we are adding material to the human objects.

1. Light simulation tab -> materials
2. Follow the prompt on the screen
3. Click the object/objects to apply the material (to apply to multiple objects at the same time hold ctrl and select all objects for the same material)
4. In the definitions panel -> Volume -> Opaque
   • Definitions panel -> Surface properties -> Library -> Browse -> Select Material
   • Selections for each object
     • People – Human skin – file: skin_sample_scan.brdf
     • TV- LCD screen - file: LCDBlackSemiMatt.brdf
     • Floor – file: Fabric Velvet Orange.brdf
     • Couches- file: Leather grey matt.brdf
5. You can see the materials in the Simulation panel

Figure 3. Adding Materials

Sources

For any source and sensor you want to use -- we need to set up an origin for it to reference. In the image, I am setting up the origin for the TV.

Setting up an Origin

1. Design Tab -> Create -> Origin
2. The origin will float on your mouse -> select the surface of the origin to attach to
3. If the origin axis is not in the correct direction -> click the “Move” button in the design tab
4. You can either by double-clicking on the axis arrow to move it 90 degrees (or you can pull on the angle adjusters)

Figure 4. Adding an Origin point to the TV

Display Source – TV

To set up the display source on the TV we must start with an origin like we see in figure 4.

1. Create an origin in the center of the TV
2. Z-axis should point to where the light is going like toward the sensors (i.e., toward the people)
3. Pull the Z-axis off the surface by 1 mm to avoid issues in the simulation.
4. Light Simulation Tab -> Sources -> Display Source
5. Select the origin for the prompt -> X axis / Y axis -> to follow the origin X / Y axis’
6. Definitions Panel -> File -> Upload picture
   • Definitions Panel -> X / Y range -> TV measurements

Figure 5. Adding the display source to the TV

Ambient Room Light

Setting up the ambient room light is very similar to the TV source.

1. Light Simulation Tab -> Sources -> Ambient -> Uniform
2. Using the original origin for the room – stick the ambient room light to this origin
3. Z axis -> pointing up in the “y direction” of the origin
4. Definitions Panel -> Type -> Blackbody -> 5000 K (light temp)

Figure 6. Adding the ambient room light source.

Sensors

Each of the “people” in this simulation will have their own human eye sensor. To begin we will need to add an origin to each of their faces with the Z-axis pointing in the direction that the light is coming in. So, the Z-axis will be pointing into their faces. Because we need to do this for so many people it is important to keep track of all the origins by renaming them. Once each face has an origin, we will start creating the sensors.

1. Light Simulation -> Sensors -> Human eye sensor
2. Click point of origin -> eye point
   • Click the trajectory of the sensor (TV origin) -> Target point
3. Definitions Panel -> General -> Colorimetric
   • Definitions Panel -> Horizontal Field of View -> Mirrored extent -> True
   • Definitions Panel -> Horizontal Field of View -> End -> 40 degrees
   • Definitions Panel -> Vertical Field of View -> Mirrored extent -> True
   • Definitions Panel -> Vertical Field of View -> End -> 20 degrees
   • If you want better resolution at end of the simulation -> increase the sampling
4. Repeat steps 1-4 for all of the people

Figure 7. Adding the human eye sensor.

Simulation

Now that we have the TV display source, ambient room light source, and separate human eye sensors for each of the people -- we can start simulating how the people will see the TV with their friend Chad in front of it.

1. Light Simulation -> Simulation -> Inverse Sensor
2. Click object prompt -> select all objects in the structure tree
   • Sources prompt -> select both TV and ambient sources (hold control and click both)
   • Sensor prompt -> select only 1 sensor for the person you are trying to see their view (this means there is 1 simulation per sensor)
3. Hit compute
4. Click the .xmp file to see the view.
5. Repeat steps 1-4 for all the sensors you wish to see.

Figure 9. Creating the Inverse simulation.

Conclusion

Through this simulation, we learned how to inverse simulate a Super Bowl party with the display light source, ambient light source, and human eye sensor. And after simulating all the people sitting around the TV, the best place to watch the game and avoid Chad is Person A! Close to the TV -- but not too close -- and at the right angle to see the whole screen.

Figure 10. Best place to sit to avoid Chad at the Super Bowl party.

Connect with the experts at Rand Simulation today to get started on purchasing Ansys SPEOS or to work on an engineering consulting project.

About the Author

In Yaelle’s role as Optical Application Engineer in the Optics Business Unit (OBU) of Rand SIM, Yaelle completes analyses of clients’ designs, helps new customers find the right software for their needs, and provides support to existing customers. Yaelle has a background in spectroscopy and lens design, has many years of experience in Ansys Zemax, and is branching into Lumerical and SPEOS. Yaelle can leverage optics and photonics simulations to meet customer needs in an ever-changing landscape.

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