Importing large 3D models

BIM/CAD models can contain a large amount of geometry that requires attention if you plan to load them to mobile devices, such as standalone VR headsets. Here are some tips for importing and working with large models in Arkio

Arkio's large-model tech

Arkio dynamically adjusts the level of detail based on your viewpoint and the device's triangle budget. Objects that are further away will render with fewer details, while objects that are closer will display details that your device can still handle.

Arkio automatically prepares and substitutes further away objects with simplified versions (called LODs). We also use occlusion culling to skip parts of the model that are obscured by other objects. This allows your device to load much larger files than would usually be possible, as only a portion of your model's triangles is rendered. You can read more about this tech in our CTO's blog.

Mobile hardware triangle budgets

Devices like the Quest use a mobile processor. Arkio supports loading large models on mobile devices; however, not all triangles will be visible from every viewpoint, as Arkio dynamically adjusts the number of triangles shown to fit the device's capabilities.

To prevent mobile devices with limited power and RAM from crashing, there is a maximum file size limit for local imports per device. When you first process larger models on more powerful hardware, such as a PC or Mac, you can still share them with other devices using an Arkio meeting or by linking your devices to the same Arkio Cloud.

Loading extremely large models

A desktop PC/Mac has more power and memory to process large imported files to Arkio resources. Once your source files are processed in Arkio, you can place them in the scene to share them with less-powerful devices via an Arkio meeting. You can also connect to the same Arkio Cloud group and synchronize new imports across all your devices to get access to these large files on your mobile devices.

For example, you might have a 35M triangle Revit building that you want to load onto a Quest. Loading files of this size via a USB cable or direct downloads via the Arkio cloud will exceed your Quest's processing capacity, so it will fail and display a warning. However, if you first import this Revit model into Arkio on a more powerful PC/Mac, you can still share this large model with your Quest via a meeting or via the Arkio Cloud that syncs the import across your other connected devices.

Large imports shared via the Arkio meeting will only show the triangles that your devices can handle. When loading extremely large files, we recommend running tests to ensure your geometry renders and performs well on your planned device, ensuring a seamless collaborative experience with your clients.

We recommend keeping the total number of imported triangles in the scene under 5 million triangles so that less powerful devices can load these models without issues. You can check your import triangles in the Arkio import panel and see the active triangles for your entire scene in the View Settings tab of the review panel.

Render settings & performance

You can gain additional performance and see more details on a standalone headset by switching to VR instead of Mixed Reality and disabling shadows, sections, and X-ray mode in view settings. These settings all affect your device's performance, and disabling them will boost the number of triangles you can see. We automatically disable shadows on mobile devices when a scene with many triangles is loaded. And you can control this setting in the View Settings tab of the review panel.

If you want to view extremely large models in VR, we recommend switching to a PC in VR (air) link mode, as your PC can display more details with better rendering quality than a standalone headset.

Variable details per device

Based on your device's triangle render budget (see the above table), some details in your model might not be loaded because the device cannot handle all the geometry. If you still want to render more details on that device, consider the following optimizations.

1) Only export the parts of the design you want to view in high detail, eg, using a Section box in Revit

2) Reduce the imported model by hiding/removing unnecessary parts of the design not needed for your review. (Hiding layers in Arkio also helps) (seeOptimizing imported geometry)

3) Look at the same scene with more powerful hardware (eg, your Quest connected to a PC in Air Link mode). Your PC can render more triangles from the same viewpoint and also features improved shadow and lighting rendering.

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

Dynamic Occlusion

Arkio simplifies geometry based on your view distance using dynamic occlusion, reducing details for parts of the model that are occluded by other geometry. This way, details closer to the user can be maintained, while objects that are obstructed or farther away have reduced detail.

When working with devices with limited triangle budgets or models with dense triangles, this can result in artifacts. Especially when your model has complex overlaps, parts of it can appear less detailed from certain viewpoints.

To prevent these low-detail areas from showing, you can reduce the density of the triangle geometry in your exports, freeing up more render budget for the important details in your design.

If you regularly experience artifacts, please contact us at support@arkio.is. We'd love to learn more about your geometry so we can improve Arkio's HLOD and Dynamic Occlusion systems for your models.