From the course: Unreal Engine: ArchViz Design Techniques

Lightmap analysis

From the course: Unreal Engine: ArchViz Design Techniques

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Lightmap analysis

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- [Instructor] Building lighting takes time, so when we're working, we want to make sure to make the most of each bake, so we can spend more time polishing our scene and fixing lighting errors. Before we can fix anything, though, let's look at how we can leverage Unreal Engine's powerful built-in tools for visualizing lighting to analyze the scene and correct issues before and after the bake. The three most common errors are light map overlap, padding issues, and light map resolution density. After every successful lighting build, Unreal's message log will warn you about each mesh with overlapping UV's, so you can work your way through the list. Simply double-click on this link to automatically highlight the asset in question in the Content Browser. Padding and light map density on the other hand, require a more discerning eye. Padding refers to the space between surfaces on a light map UV. If there isn't enough, light and dark will appear to bleed through at the seams and edges of meshes in the scene, and is probably one of the most frequent frustrations for ArchViz experts and beginners alike. Here's an example of light bleed from lack of padding in action. Light map density on the other hand, refers to the resolution of the light map, relative to the overall size of the asset in the scene. For example, a floor will need more texture resolution than a keyboard, since there's more area on which to cast light and shadow. To visualize this, hit alt zero, or head up to the view mode here, go down to Optimization Viewmodes, and select light map density. A good rule of thumb is that blue is too low, but red is too high. While something like green to orange is considered the Goldilocks Zone. Practically speaking, blue means that your shadows will be jagged and low resolution, and red assets mean that your light bake will take a bit longer. If I turn on the _decor_office, you can see a lot more green and red. All the red assets in the scene here are small enough that they're using a tiny light map, and it's still considered too dense. So we won't worry too much about them unless the light bake reveals something unusual. Now that we have a couple lenses to see our lighting through, we're ready to start fixing these issues and setting our scene up for success.

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