Learn-by-Example Modelling 04: Multi-layered Normal Maps

[G|I|Sandy]

Introduction

I assume you know how to make basic normal maps with photoshop or gimp. Otherwise here is a good tutorial for complete beginners: How to make a normal texture file. Another method that produces much better results is by sculpting a high-poly model and extracting its normal map: Creating High-Res Normal Maps. However, this method is quite tedious and not all have access to that kind of software. You can see another inspiring example by Rusichi team: The awesome powers of normal mapping. Now in this tutorial I will show how to make a high-quality normal map, similar to those achieved by Rusichi, using the standard NVIDIA Normal Map Filter.

The general procedure:

- Apply the Normal Map Filter with milder settings than usual (i use -3 or -5).
- Duplicate the layer.
- Set the blending mod of the duplicate to "Overlay".
- Use Gaussian Blur filter at 1.0 pixels (depends on your preference).
- After making the first duplicate and blurring it, press Ctrl + J (duplicate) and then Ctrl + F (last filter which is Gaussian Blur), repeat.
- Notice how the normal map becomes deeper and much more realistic. Do not overdo, 5-10 layers are enough.
- Flatten the layers into a single layer.
- Optional: Overlay messes up the heights (appear to bright), so to fix it go to Normal Map Filter and select "Normalize Only", run the filter.

Overall, you should have each following layer to be more blurry and all layers other than the initial one must be set to "Overlay", dont forget to flatten and normalize the image.

Implementation

A very important point: You do not have to use the same texture for the normal map. It is generally better to use stronger contrast for a normal map. In this case (see below), the tunic has a pattern that may not look good on the normal map with this method. I removed the pattern and set the opacity of the shadows/highlights tp 100% (vs 10% in the main texture). Also notice I kept the shadows on the main texture because this is where a shadow from a belt would be (belt is a separate 3d part). Below is the comparison between the standard one-layer normal map and the multi-layered normal map (both made using the "Texture for the Normal Map Filter" on the previous image). In game:

Comments

Overall, this procedure produces deep and nice looking normal maps not just for hand-drawn folded textures. However I would like to point out that this procedure may not be good for very detailed textures like chainmail. In the above screenshots i have used single layer normal maps for chainmail. In the main texture i reduced the opacity of the shadows&highlights so as to allow the engine to generate the effect using normal maps. While very dark areas on a texture may not look good, using higher opacity can provide interesting results. At 30% opacity on a colored texture:

Making a Texture with Folds

You will need two layers, one layer is set to "Multiply" and will contain black color/shadows. The other layer is set to "Overlay" and will contain white color/highlights. The advantage of using multiply and overlay blending mods is that the colors will not be flat white and black, but will adhere to the background and look smooth. For the multiply layer use a black colored brush and paint the parts where you expect a shadow to fall. Use the "smudge tool" to spread the shadows smoothly. Do the same for highlights, but with white color. You may choose to do everything in a single "Normal" blending mod layer. It will not look as good, but it is hard to see any difference in the case of a grey texture. Just a tip for the future. The comparison between using Multiply and Overlay blending mods vs default Normal mode is shown below. The Multiply and Overlay layers are at 30% opacity. The textures with folds can be found attached.

I did not have much time for this tutorial, hence the quality, but i wanted to share this awesome method i discovered a long time ago. Next tutorial will most probably be on texturing.

In pursuit of higher quality modifications,
Sandy

[Lifthrasir]

Thanks for that tuto. Very useful as usual