How do you balance quality and performance when using normal maps in real-time rendering?

1 What are normal maps?

Normal maps are a type of texture map that store the direction of the surface normals for each pixel of a 3D model. Surface normals are vectors that point perpendicular to the surface and affect how light reflects and bounces off the model. By using normal maps, you can simulate the appearance of bumps, dents, wrinkles, and other details on a flat or low-poly surface.

2 How to create normal maps?

There are different ways to create normal maps, depending on your needs and preferences. One common method is to bake them from a high-poly model to a low-poly model. This means that you create a detailed version of your model with more polygons and sculpt the details you want, then project them onto a simpler version with fewer polygons and a UV map. The UV map is a 2D representation of how the 3D model is unwrapped and mapped to a texture. You can use software tools such as Blender, Maya, or ZBrush to bake normal maps.

3 How to apply normal maps?

Once you have your normal map, you need to apply it to your low-poly model in your rendering engine or software. You can do this by assigning the normal map to the normal or bump slot of your material or shader. The normal map will then modify the surface normals of your model according to the color values of the texture. You can also adjust the intensity or strength of the normal map to control how much it affects the model.

4 How to optimize normal maps?

Normal maps can significantly improve the visual quality of your models, however, they come with a cost in terms of memory usage and rendering time. To balance quality and performance, you need to optimize your normal maps. Use the correct resolution and format for your normal maps; the resolution should match the size and detail of your model and the format should support compression and mipmapping. Additionally, make sure to use the correct color space and channel, tangent space and orientation, as well as lighting and shading for your normal maps. For example, you can use PNG or TGA for lossless compression or DDS or BC5 for lossy compression and mipmapping. Furthermore, the color space should be linear instead of sRGB to avoid gamma correction and distortion, while the channel should be RGB instead of alpha to avoid transparency issues and artifacts. Finally, when it comes to lighting and shading, you need to use appropriate models and techniques such as PBR or HDR to achieve realistic results.

5 How to test normal maps?

The final step of using normal maps is to test them in your target platform and environment. You need to check how they look and perform in different scenarios and conditions, such as different resolutions, screen sizes, devices, lighting settings, camera angles, and distances. You also need to check for any errors or issues, such as seams, stretching, flipping, or aliasing. You can use tools such as Marmoset Toolbag, Substance Painter, or Unreal Engine to preview and test your normal maps.