Trying to speed up your 3D render? Learn how to optimize your CAD model for rendering!

Imagine you work in a 3D visualization team in an engineering company. As part of a new marketing initiative at your company, you have been tasked with creating a high-quality render of the newest design for an oil refinery plant. You are handed a CAD file from the engineering team, and very quickly realize that the size and complexity of the file will create challenges for your visualization pipeline.

Not only is the design file not performant for rendering in engines like V-Ray, opening it in design software like Maya might take anywhere between 20 to 30 minutes! This is where 3D optimization proves to be useful, and for the most part, necessary. For many 3D teams, optimizing a 3D model before pushing it into the next stage in the pipeline is a big time-saver.

Let’s go over some tips on the best ways to optimize your 3D CAD model for rendering.

1. Remove unnecessary geometry

All objects in a scene – regardless of their location, will still be considered in your render engine’s lighting calculations. Which means that even if an object is not going to be in your final visualization, it’s still being processed during the render, pointlessly increasing your render time. Also, pay attention to interior or exterior assets that won’t be in your visualization. If you’re rendering an interior view of a model, simply delete the exterior parts, and vice versa. Removing unnecessary geometry can significantly improve your render time.

Remove all the geometry that isn’t needed for the render, this includes:

  • Geometry that isn’t visible to the camera and therefore won’t be visible in the final render
  • Geometry that is hidden underneath other geometry, or is hidden by other objects (for example, if you’re rendering the outside of the model, all the inside assets can simply be deleted).

2. Instantiate duplicate assets

Repeated assets, or duplicates, can either be intentionally or unintentionally repeated throughout a 3D file. For example, you may have accidentally created overlapping meshes that sit on top of each other, which is commonly caused when you extrude or manipulate mesh. Or, more commonly, your model may have lost its instantiation during conversion and now there are hundreds of duplicate assets throughout your model, like screws, springs, or wires. Repeated assets are a major obstacle to render times, especially when using cloud service and render farms, and optimizing them is a great way to improve your model’s performance for rendering.

Instantiating duplicate assets in your scene or assembly will significantly reduce your file size and RAM usage. This is because instancing will allow 3D software to only store the data of a single mesh in memory and in the file. At this point you may be thinking, this all sounds great but finding and grouping duplicate objects manually can be a tedious process. This is where a 3D CAD optimization software like Meshmatic can help. Meshmatic’s Duplicate Detector will quickly and accurately finds duplicate assets in your scene, and enable you to instantiate duplicates with a click of a button. This will significantly reduce polycount and file size.


Bottom image highlights all the duplicate assets found in the top image.

3. Adjust your LOD’s

Not all assets require the highest level of detail for your visualization project, especially if they’re background assets or not the main attraction in your render! Optimize your assets based on their distance from the camera: the further from the camera, the lower the required LOD (level of detail). For example, if you’re rendering a plant model as part of a scene, the background assets should be optimized with LOD’s to save render costs.


Top image: before LOD generation – Bottom image: after LOD generation

4. Delete your history

Another great tip for optimizing your 3D model for rendering is to make sure you delete your history before importing into the render engine. If you’re working on the final details of your render in Maya, or other 3D software, all the modifications you make add to your file history – and increase your file size. This will in turn increase your render costs which you want to avoid.

5. Fix normals

Make sure your normals are facing the right direction before you begin rendering. If you render and the normals are inconsistent, or incorrect, you’ll have to go back to your design software, fix them, and re-render. This would be a waste of time, especially for large models.

6. Export to a neutral file format

A final tip is to export your design file in a neutral file format. This will make the import process to render engines a lot easier. However, converting from a CAD format – which most engineering and architectural models are written in, to a neutral format – like polygon mesh, can be both time consuming and prone to data damage or data loss.

Meshmatic can easily and accurately convert CAD files to polygon mesh by rewriting 3D files in a structure that is designed to make the file easily digestible by game and render engines. Some of the tasks that Meshmatic does include instancing repeated assets, generating smooth normals, optimizing the outliner, grouping small objects and small planes, that may not be needed in the visualization.


Final render of the oil refinery station

Final thoughts

3D visualization teams spend a lot of time working with large and complex CAD models. These models are usually developed by engineering or architectural design teams and contain many thousands of parts, detailed file structures, and meta data such as supplier information. To render and visualize these models, optimization is essential.

By automating many of the optimization and file preparation tasks, Meshmatic provides a fast and accurate way of converting CAD files into content that is highly performant for rendering and real-time applications.

Sign up today to get the latest information on optimizing CAD models with Meshmatic.