Importing large 3D models on any device

BIM/CAD models can contain numerous details that require special attention if you plan to load this geometry onto smartphones and mobile VR devices. Here are some tips for importing and working with large models in Arkio

Arkio's large-model tech

To enable the loading of large models on mobile devices, 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 the 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 larger files than typically possible, as only a small portion of a model's visible triangles is rendered at a time. You can read more about this tech in our CTO's blog

Large models on mobile hardware

Devices like the Quest use a mobile processor. Arkio supports the loading of large models, but not all the triangles will be visible from every angle, as we dynamically adjust the number of triangles shown to fit the device's render budget.

To prevent mobile devices with limited power and RAM from crashing, there is a maximum file size limit for imports per device. When this maximum is exceeded, this model can not be processed. However, you can first process and place larger models on more powerful hardware, such as a PC or Mac, and then share these models with your less powerful devices using an Arkio meeting.

Loading extremely large files

A desktop PC/Mac has more memory and power to process large imported files to the Arkio resources. Once your source files are processed in Arkio, you can place them in the scene and share them with less powerful devices using an Arkio meeting.

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 the Arkio cloud will be too large for your device to handle, so it will fail and display a warning. However, if you first import this Revit model in Arkio on a powerful PC/Mac and then place it in the Arkio scene, you can share this large model with your Quest.

Large imports shared via the Arkio meeting will only show the triangles that your devices can still handle. When loading extremely large files, we recommend conducting tests to ensure your geometry looks and performs well on the device you plan to use for a seamless collaborative experience.

We recommend keeping the total number of imported triangles in the scene under 5 million triangles so all devices can load these models without issues. You can check your total triangles in the Arkio import panel or the View Settings section of Arkio's review panel.

You can gain additional performance and see more details on a standalone headset by switching to VR instead of Mixed Reality and disabling shadows, ambient occlusion, sections, or X-ray mode in view settings, as this will boost performance by simplifying the rendering process.

If you want to view extremely large models in VR, we also recommend switching to a PC in VR (air) link mode, as your PC will be able to display more details and enhance render quality compared to a standalone headset.

Variable details per device

Based on your device's triangle render budgets (see the table above), some details in your model cannot be loaded because there is too much geometry for that device to handle. If you still wish to see more details about that device, consider the following options.

1) Reduce the imported model to only include the geometry you want to experience in higher detail and remove unnecessary parts that are not needed. You can read more about optimizing your geometry here

2) Look at the same scene with more powerful hardware (eg. your Quest connected to a PC in Air link mode) Your PC can render a higher number of triangles from the same viewpoint and also has improved rendering using ambient occlusion and better shadows and lighting see below comparison between Quest and PC VR from the same viewpoint.

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

Dynamic Occlusion

Arkio simplifies the geometry based on your view distance using a technique called dynamic occlusion, which reduces 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 and further away have reduced details.

When working with devices that have low rendering budgets and dense triangle models, this can result in artifacts for certain viewpoints. Especially when your model has complex overlaps, it can result in parts of the model looking less detailed and showing artifacts.

To prevent these low details from showing, you can reduce the dense triangle geometry in your exports, allowing more render budget to remain available for the most important details in your design.

If you regularly experience these artifacts, we'd love to learn more about your models so we can improve Arkio's HLOD system and Dynamic Occlusion for that type of geometry.