VR is different than traditional architectural rendering in that it has limitations for performance. Previously, architectural renderings took a few hours to multiple days. With VR experiences, we must render a new image 60 to 90 times per second! This is quite a drastic change.
Bad VR performance can lead to judder and VR nausea. We must therefore optimize models to use the least amount of triangles and textures possible. While a lot of the optimization is done on our servers, we can only do so much if the model is very complex.
One of the most basic ways of calculating a model's complexity is through it's triangle count. We will go through some tricks, tools and strategies to reduce triangle counts in your Revit architectural models.
- Set specific 3D views for your VR exports depending on what you are looking to demonstrate. Will you be going into the plenum and looking at in-wall plumbing? Are you going to check fire exit stairs? If not, hide these objects for the VR view.
- If you use Spaces or Rooms, you can create a schedule that contains all your model elements and their Rooms or Spaces. You can then select all the elements in a certain room (such as the plenum) and hide them. This is probably the fastest way to hide multiple objects with certainty.
- You can add a custom parameter to all objects, such as "VR-Visible" and then select all of the items that do not have this property in a schedule and hide the item in your view.
- Detail levels should be set to Medium. Coarse will remove the structural columns and Fine will add rounded edges to the columns, adding way too much geometry. I would consider doing this especially for furniture and other assets that you will be re-using in the future. It may be worth contacting the furniture manufacturers about the need for geometric detail levels in their BIM families.
- You can use detail levels in Revit's family systems. Just make sure the Medium detail level will give you enough detail for VR and your other purposes.
- You can create Subcategories and control these with the Visibility Settings.
- You can create a custom View Visibility/Graphic override, great for turning off things like rebar.
- You can turn off Worksets.
- You can manually hide things.
- You can use selection sets to hide objects.
- You can make preset 3D plenum views to easily select plenum objects that are hidden and add them to your "hidden" selection sets.