Performance Optimization Guide for FVS Models

Application Scenario

This document, adapted for FVS, introduces how to optimize models.

The model processing methods in the modelling software introduced in the document differ from those used in other 3D visualization tools.

Model optimization includes model processing and texture processing.

Notes

Sections with titles marked by an asterisk (*) are key points of focus in the modelling software.

Currently, only models of the GLB (GLTF 2.0) are supported in FVS. You can convert existing models to this format or directly export models to this format from modelling software.

The following lists common methods for converting models of various formats to GLB.

• Online converter for 3D models

• 3D file converter

• Exporting GLB files from 3ds Max via Babylon.js Exporter

• Exporting GLB files from SolidWorks via the third-party plugin: SolidWorks Export Plugin.zip

• Exporting GLB files from Blender

• Exporting GLB files from Maya

• Exporting GLB files from Cinema 4D

• Exporting GLB files from SketchUp

• Exporting FBX/OBJ/DAE/STL files to GLB files in Blender

Mesh/Object Merging *

1. Mesh count definition

• The mesh count is a key factor influencing the performance of GLB models in FVS.

• The mesh count is the total number of meshes in a GLB file. Since each mesh can only have one material, if a single object in 3D software is assigned multiple materials, the mesh count for the object equals the number of materials assigned to it.

• The mesh count differs from the object count in 3D software. While an object can be assigned multiple materials, a mesh can only have one material. When the mesh count is calculated, an object with multiple materials is counted as multiple meshes. In other words, the object is split into separate meshes based on the number of used materials.

Note: 

In a GLB file, each mesh can have only one material. Therefore, when a model is exported to the GLB file, objects assigned multiple materials are split into multiple meshes, causing the mesh count to exceed the object count in 3D software.

2. Mesh count checking

You can open Babylon.js Sandbox with Chrome or Microsoft Edge, upload the GLB file, and the mesh count is displayed under Statistics > Count on the right panel.

3. Recommended mesh count

You are advised to keep the total mesh count of all objects in a 3D scene below 3,000. Exceeding this limit may result in performance issues, such as preview lag and low frame rates.

4. Method

In 3D software, if a scene contains many objects, you can reduce the object count by merging objects that are not required for interaction or specific business purposes, thereby reducing the mesh count after the model export.

In Blender, you can select the desired objects and press Ctrl + J to merge them into the last selected object.

If the mesh count is high because objects are assigned an excessive number of materials, you can reduce the number of textures and thus materials to lower the mesh count. (For details about how to reduce the texture count, see the "Material/Texture Count Reduction" section.

5. You can also use a model optimization tool to merge the meshes. For details about how to use GLB-Optimizer, a model optimization tool, see Custom 3D Model Check.

Linked Duplicate *

1. The effect of linked duplicates

Linked duplicates allow multiple objects to share the data with the original object, reducing file size and improving viewport performance (FPS).

The optimization method applies to scenes containing many identical objects, such as machines, warehouse shelves, or goods.

Depending on the modelling stage, you can optimize models either during or after the modelling process.

2. Method

• During the modelling process:

In Blender, select the object you want to duplicate, and press ALT + D to create a linked duplicate. After duplication, the number of linked duplicates will be displayed on the right Data panel.

For example, in the following figure, 3 is the number of linked duplicates.

• After the modelling process:

If all objects are completed and linked duplicates were not created during modelling, you can link the existing object data: Select identical objects, and press Ctrl + L to link object data.

Pressing Ctrl + L will open the Link/Transfer Data menu. Click Link Object Data, as shown in the following figure. Similarly, the number of linked objects will be displayed on the right Data panel, for example, 14 shown in the following figure.

Note:

Excessive linked objects can increase the total object (mesh) count in a scene. To optimize models effectively, you can merge objects that are not required for interaction or specific business purposes, and create linked duplicates or link data for objects that require interaction or are essential for business use.

Face Count Reduction

1. Object face count checking

In Blender, click the dropdown arrow on the upper-right corner to open the Viewport Overlays panel, and tick Statistics. The face count of an object is displayed in Faces, as shown in the following figure.

2. Recommended face count

You are advised to keep the total face count of a GLB model under 10 million. Exceeding this limit may result in issues such as large file size and slow loading.

3. Method

Three methods are available for reducing the face count: using low-poly assets, performing manual retopology, and using built-in mesh simplification functions of modelling software.

• Using low-poly assets

In a scene, priority should be given to objects required for business purposes. For other background or decorative objects, such as sculptures, vegetation, decorations, vehicles, and billboards, you are advised to use low-poly assets.

• Performing manual retopology

If an existing model has excessive geometric detail or a high face count due to differences in modeling methods, software, or model conversion, you are advised to recreate a model with cleaner topology to replace the original one.

The following figures show the face count difference of a cylinder. The original cylinder with more than 1,300 faces is replaced with a simplified one with only about 100 faces.

• Using built-in mesh simplification functions to simplify models

You can use the built-in functions of modelling software to simplify models. In Blender, you can modify parameters in Collapse, Un-Subdivide, and Planar of the Decimate modifier to simplify objects with excessive faces.

The following figures show the face count reduction implemented with the Decimate modifier.

Note: 

You need to apply the modifier for the simplification to take effect.

4. You can also use a model optimization tool to reduce the face count. For details about how to use GLB-Optimizer, a model optimization tool, see Custom 3D Model Check.

Draco Compression *

In the export settings of Blender, you should tick Compression (default compression settings recommended) before the export.

Draco compression can significantly reduce the size of mesh data in the file while exerting minimal impact on visual quality. In some cases, however, compression may cause mesh artifacts in certain models. If this occurs, triangulate the mesh before the export to resolve the issue.

1. Method

In the export settings of Blender, tick Compression to apply Draco compression.

2. You can also use a model optimization tool to implement Draco compression. For details about how to use GLB-Optimizer, a model optimization tool, see Custom 3D Model Check.

Model Detail Balance

1. Appropriate detail reduction

When a model is intended primarily for macro-level visualization, excessive geometric detail is often unnecessary due to the long viewing distance. In such cases, small components or non-essential parts can be removed to reduce negative performance impacts. Alternatively, you can use simplified geometric shapes to represent complex structures.

For example, the details of small objects are often barely visible from a distance in such a large workshop, as shown in the following figure. (If close-up viewing is required, you are advised to retain the primary structural components while removing small parts, such as screws.)

2. Appropriate detail retention

When the view is zoomed in on a production line or an individual piece of equipment, due to the shorter viewing distance, you are advised to retain more geometric details.

Unused Data Cleanup

You can clean up unused materials, meshes, brushes, and other residual data in modelling software to reduce the file size.

Method

In Blender, switch to Unused Data in Display Mode on the upper-right corner, and click Purge and Delete. In this way, all unused data that is no longer referenced by objects will be automatically removed, as shown in the following figure. 

Texture Map Usage *

You can use texture maps to represent model details instead of creating complex geometry.

1. Method

A model that appears highly detailed is actually created by applying a texture map to a simple base mesh, as shown in the following figures. This method can reduce the effort required to model detailed elements such as doors and windows, while also lowering the total face count.

Note: 

This method requires the modeler to be familiar with UV mapping.

Texture Size Reduction

1. You can extract the texture images used by a model and compress them with image compression tools to reduce the image size.

Texture image should be compressed to less than 2 MB, and non-essential ones should be reduced to less than 500 KB.

Many commonly used texture images are relatively large, and using them without compression can result in an

relatively large GLB file.

2. You can also use a model optimization tool to reduce the size of texture images. For details about how to use GLB-Optimizer, a model optimization tool, see Custom 3D Model Check. 

Texture Format Optimization

Preferably, texture images should be square and tileable.

Also, you are advised to convert texture images to the JPG format at 2K resolution.

The resolution of texture images should follow a power-of-two format, for example, 256, 512, and 1024. In most cases, the resolution of commonly used texture images should be kept below 2K. For large scenes, higher-resolution textures can be used to maintain visual clarity.

Note: 

In modelling software, the resolution of texture images is automatically optimized based on their positions in the scene to improve the rendering efficiency. Therefore, texture resolutions should follow a power-of-two format, so that texture details can be processed efficiently.

For textures requiring transparency, you are advised to convert the images to the PNG format with an 8-bit color depth at 2K resolution.

Material/Texture Count Reduction

1. Texture atlasing

For textures that do not require tiling, you can combine multiple texture images into a single texture atlas and assign it to a material. This allows textures originally used across multiple materials to be combined into a single material and applied to different objects via UV mapping, as shown in the following figure. (The technique is commonly used for objects such as advertising images, display pictures, doors, and windows.)

2. Texture baking

Texture baking allows you to bake the texture details of multiple objects into a single texture map. This reduces the number of textures and materials, thereby decreasing the overall file size.

You are advised to use the SimpleBake plugin in Blender to perform texture baking.

3. You can also use a model optimization tool to simplify textures. For details about how to use GLB-Optimizer, a model optimization tool, see Custom 3D Model Check.