What do we Need to Consider When We Create 3D Models for Unreal Engine with Houdini?

When we are building 3D models for Unreal Engine we need to optimize our geometry. Optimizing our geometry can mean several things.

Level Of Detail Models

Unreal Engine understands Level of Detail models, referred to as L.O.D.s.  These are 3D models that are of the same model, but with varying polygon counts. This is one thing that we can automate in Houdini. Houdini’s Polygon Reduction tool can create 3D models with different polygon counts. We can name our groups so that Unreal Engine understands that these are L.O.D.s.

Lightmaps

We have real-time lighting and global illumination in Unreal with Lumen. This might not work for applications like Virtual or Augmented Reality. In these cases, there could be the need to do Light Baking. Light baking is the process of rendering our lighting onto our geometry. We do this with the use of special texture maps. These texture maps are called Lightmaps. In Unreal Engine, they exist on a separate UV layer, UV1. Unreal will create Lightmaps when we import new geometry.  We can also provide our own UV Channel that Unreal will recognize. This can improve the efficiency of our Lightmaps. In Houdini, we can use a node like UV Layout. UV Layout uses a special algorithm to pack our Lightmaps as tight as possible.

To learn more about UV Mapping in Houdini read How to Master UV Mapping in Houdini

Packed Primitives

Packed Primitives are a way of archiving our geometry that can improve efficiency. This does involve some slight technical oversight. We want to make sure that we have a correct Name Attribute. Then we would use either an Assemble Sop or a Pack Sop.

You can read about Packed Primitives on the Side Effects Website

Terrains in Unreal Engine

Creating terrain in Unreal Engine is through a heightfield. A heightfield is a special type of volume that is only two-dimensional. You can create terrains in Unreal Engine. Unreal has several brushes for manipulating terrain. Houdini has a large set of heightfield tools. In Houdini, we can create a Houdini Digital Asset and bring that into Unreal. This workflow has several advantages.

• We can define our own terrain layers that useful in a Landscape Material
• We can create layers to Instance Procedural Foliage with Grass Maps
• We can perform erosion simulations in Houdini
• We can create custom masks based on landscape features. We can use slope, height, direction, and others.

Learn More about How to Start Learning 3D Modeling

3D Models for Unreal Engine with Houdini

Check out the Asset Bash 3D Models and Modules made with Houdini