Why Does it Matter for Building Design and Construction?

People have a very hard time visualizing architectural concepts. It’s nearly impossible for most people to fully understand what an architectural space will be like by viewing 2D floor plans, illustrations, animations or scale models. These are all ultimately abstract and distorted ways of visualizing a design, and not at all representative of how we experience architecture in the real world.

With virtual reality, we can gain a very holistic understanding of what the building will feel like before investing the massive amount of resources it takes to make it a reality. It’s a lot easier to change a pixel than it is to move a brick wall after it’s built. VR helps people understand architecture in a way nothing else comes close to, which we believe will ultimately lead to the creation of better, more efficient built environment. _

BIM -> VR

For architectural visualization applications, the simulated environment is most often created with a real-time engine like Unity3D, where a 3D model – often exported from Revit, SketchUp, or other BIM applications, is used as a basis for creating the virtual reality application. Materials and lighting are then introduced, and the virtual reality application is published as a file that anyone with the appropriate VR hardware can access and experience. _

The Importance of Framerate

Before we get too far ahead, I first want to make an important note about framerate, and why it’s vital to quality architectural visualization in virtual reality. In VR, framerate is defined as the number of times per second a ‘frame’ or rendered image is displayed on the screen, most often expressed in frames per second (FPS). If the framerate is low, or a number of other factors aren’t performing adequately, the viewer can experience ‘lag’ or ‘judder,’ where the simulated 3D environment they’re viewing isn’t properly mirroring their physical movement and rotation. This is one of the most significant and avoidable causes of motion sickness, or what is sometimes called ‘simulator sickness.’ _

_

One of the biggest contributors to low framerate, is when complex 3D models or very large graphics are being displayed, but the hardware system being used doesn’t have the capability of displaying the same at an adequate framerate. This can most often happen with hardware like Google Cardboard and Gear VR, as we’ll describe in greater detail below. Architectural models exported from software like Revit, ArchiCAD or SketchUp are notoriously complex when compared to ‘game ready’ models that have been prepared specifically around achieving high framerate. Professional VR developers employ numerous tricks to alleviate this issue, such as occlusion culling, baked lighting, remeshing complex geometry and more. _

If you are attempting to provide architectural visualization in virtual reality in any capacity, you absolutely must be sure to achieve a lag and judder-free experience. If you don’t, you will invariably cause motion sickness for many people who are trying VR for the first time, a perception that cannot be easily undone. _

Spectrum of VR Hardware Choices

Not all virtual reality hardware is created equal. They range from low cost / low quality, all the way to high cost / high quality. Each of these technologies has a place in architectural visualization. On the lower cost / high convenience / lower overall quality end of the spectrum, you’ll use your own cell phone as the display and depend on the phone’s internal rotational tracking sensors. On the higher cost / lower portability end you’ll need a dedicated, higher end PC to use it, and depend on the full capabilities of a dedicated GPU. This end of the spectrum also includes projection rooms, or CAVE systems. This post will not include an evaluation of projection-based systems, and will instead focus on the current generation of head-mounted display (HMD) options that will soon be available to consumer markets. _