Working with large 3D imports on any device

BIM/CAD models can have lots of details that need special attention if you plan to load all geometry on smartphones and mobile VR devices. Here are some tips for importing and working with large models in Arkio

Arkio's large-model tech

To allow the loading of large models on devices like the Meta Quest 3 Arkio dynamically adjusts the level of detail based on your viewpoint and device triangle budget. Things that are further away will render with fewer details and objects that are closer will only show details that the device can handle. 

We substitute further away objects with more simplified versions (called LODs, Levels of Detail). We also remove objects fully obscured by other objects (Occlusion culling). This way, we can render only a small portion of a model's triangles while giving the appearance of rendering it fully. You can read more about this technology on our CTO's blog

Large models on mobile hardware

Devices like the Quest use a mobile processor, Meta recommends not loading more than 250K triangles on a Quest 3 to keep a comfortable framerate. Arkio supports loading much larger models up to 20M triangles on Quest 3 but not all of these triangles will be visible at the same time as we dynamically adjust the number of triangles shown to fit the device's render budget for Arkio.

To prevent mobile devices with limited processing power and RAM from crashing while importing a large file we added a maximum to the file size and triangles that can be imported locally. When this maximum is exceeded the models can not be processed locally. However, you can still process and place these large models on more powerful hardware like a PC/Mac first and then share these large models with less powerful devices using an Arkio meeting. See the extremely large model paragraph for more info.

Variable details per device

Based on what device you are using there are different triangle render budgets (see the above table) this can result in some details in your model never loading fully as there is simply too much geometry for that device. In case you still want to see these details on that device you can consider two solutions.

1) Reduce the imported model to only the geometry you want to see in more detail and remove other unnecessary parts or details that should not be loaded. You can read more about optimizing your geometry here

2) Look at the same model with more powerful hardware like a PC connected to a headset. (eg. your Quest in link mode) so you can render a much higher number of triangles from the same viewpoint with enhanced rendering and ambient shadows that are possible on PC see the below for the comparison.

828K/10.9M on Quest 3	5.4M/10.9M on Quest in PC link mode
636K/10.9M on Quest 3	5.9M/10.9M on Quest in PC link mode
747K/10.9M on Quest 3	5.0M/10.9M on Quest in PC link mode

Loading extremely large files

On a PC you will have a lot more memory and power to process large files into Arkio resources. Once your source files are processed they can be placed in the scene and shared with less powerful devices like a standalone headset or smartphone.

As an example, you might have a 32M triangles Revit office building that you want to load on a Quest. Loading files this size on your device with a USB cable or via the Arkio cloud will be too much for your device to process by itself so it will fail and give you a warning. However, if you first import this Revit model locally on your more powerful Revit PC and then place it in the Arkio scene you can still share this model with your Quest 3 using an Arkio meeting.

Extremely large imported resources will share from your meeting scene to less powerful hardware but will only show fewer details as your device will crash when trying to show more geometry. When loading extremely large files we recommend always doing some tests first to make sure your geometry loads well on the planned device so users will have a good experience. 

We recommend keeping your total number of imported triangles in the scene under 5M triangles so every device can load models without issues. You can check your total triangles after the Exports from the Plugins in the Arkio import panel or when opening the 3D exported file with the Windows 3D viewer.

If you want to view extremely large models on Quest we recommend switching to PC in VR link mode as your PC will be able to show more details and add additional rendering quality with ambient shadows that are too expensive for a Quest headset to render. 

You can also gain a bit more performance on a standalone Quest headset when rendering large models by switching to VR instead of Mixed Reality and disabling your shadows, sections, or X-ray mode in view settings as this will boost performance by simplifying the rendering load on your headset.