BIM models tend to be heavy and need some special attention before you can load their geometry into Arkio on smartphones and VR devices. Here are some steps to keep your models clean so they can be loaded without problems by anyone in your meetings.
Quest and mobile hardware
Since the Oculus Quest uses a mobile processor Oculus recommends not to load more than 100.000 polygons in a scene to keep the experience run at a comfortable 72 fps. We ran tests with imported models up to 400.000 polygons but we don't recommend this as performance will be low and the experience will be uncomfortable.
To prevent less powerful devices from crashing when heavy 3D models get loaded or shared in a meeting we added a maximum number of polygons and file size. If models exceed the maximum number of polygons the models will only be partially loaded when the maximum file size is exceeded the models will not be loaded at all. We recommend keeping your imports under 250.000 polygons so all devices can load them in a comfortable experience.
|Platform||Max. number of polygons||Max. file size|
|Windows PC||20.000.000||2.000 Mb|
|Oculus Quest||450.000||90 Mb|
If you want to load bigger 3D files in VR we recommend using a powerful PC connected to a wired VR headset. (like your Oculus Quest in link mode with a USB cable) The maximum number of polygons supported by PC hardware is a lot higher and depending on your Memory, CPU and GPU Arkio can import up to >10 Milion polygon models. You can check your polygon count during the Revit export or when opening the OBJ file with the Windows 3D viewer.
Revit model preparation - best practices
- Use a 3D section Box to crop away your model into part of the scene
- For exporting, turn off (sub)categories you don't need and hide elements and worksets that are not required (you don’t need to export furniture and casework if you will only work on the exterior)
- Make use of Revit’s built-in detail visibility settings (Course, Medium, Detailed) to reduce the detail of specific sub-elements in Revit families
- The following categories can be hidden by default: Railings, Planting, Lighting Fixtures, Plumbing Fixtures, Electrical Equipment, and all Mechanical, Electrical and Piping Categories.
- Use Revit families that are simple don't add barely visible corner fillets, non-essential elements like 3D text, screws, and bolts or unessential curved surfaces, these objects not only tend to slow down Revit it also has a huge impact on other software and mesh-based programs like 3D Studio Max
- Avoid loading CAD, Rhino and Sketchup references in your Revit model, not only will they make Revit slow they will also not translate that well to VR
- Avoid thin/overlapping surfaces and objects, as they might result in Z-fighting if plan to work on large scales up to 1:1000, try to use minimum thicknesses of 100mm for solid objects
- Apply correct materials to objects and simplify their count and usage. This will keep your Revit models organized and will make the conversion process to VR faster. A useful workflow for this is making a multi-category Schedule and organizing it by material name and volume so you can easily spot unnecessary and double namings in your project:
Manual mesh optimization - step by step
1) Export a cleaned and prepared Revit 3D section box scene to an FBX format
2) Load the FBX file in 3D Studio using Link FBX
3) Select Autodesk Revit Combine by material and bind the link after import (needed to see number of polygons and optimize the model later on)
4) Delete all the non-mesh elements in the scene (camera, lights, and groups are not supported by OBJ)
5) Your Revit origin point might not make sense for placing/loading the object in Arkio, you can fix this for all meshes by right-clicking on the transform-tool and filling in a better position (or use the transform arrow with less accuracy)
6) click the [+] on your 3DS max viewport and configure the viewport to show the polygon statistics of your view
7) check the number of polygons of the meshes and use ProOptimize to the ones above 62.000 polygons. Try to keep the total number below 240.000 polygons to keep VR performance high.
8) Optimize a high poly mesh using ProOptimize tool. With the object selected Click on Modifier Tab > drop down list, search for “ProOptimizer”. Select the checkbox to keep the textures, click ‘Calculate’ > Reduce the ‘Vertex %’ to desired level and press ‘Enter. The polygon number of the selected object should be significantly reduced. You can check if the resulting geometry is acceptable in the scene.
9) Autodesk uses a different material system that other apps so the materials have to be converted to Standard Materials using a script or the built-in Scene converter. And the following settings:
10) Now we reached the final step of exporting the OBJ using the following settings. (Don’t forget to check the “flip YZ axis” checkbox as Autodesk uses a different coordinate system).
Congratulations! you are now able to prepare 3D files to load into any device using Arkio. Unfortunately, 3D Studio’s OBJ exporting functionality could be a bit broken at times so please make sure to check your resulted OBJ file by opening the file in another application (Rhinoceros, 3DStudio or Unity) before you try to load the files in Arkio using your \Documents\Arkio\Import\Models folder