Riverology — Normal Maps
Last updated: 2025-12-09
Prerequisites
- Unreal Engine 5.6 or newer.
- Riverology installed and configured (see the Setup page).
- At least one BP_Riverology river placed in your level.
- Basic familiarity with Normal Maps and Materials in Unreal Engine.
Notes
- Normal maps define the surface detail of the water, creating the appearance of small waves, ripples, and surface perturbations without adding geometric complexity. They are essential for realistic water rendering.
- Riverology uses animated normal maps that scroll across the water surface, simulating the constant motion of flowing water. The animation speed and scale can be adjusted to match different river conditions.
- Normal maps affect reflections, refraction, specular highlights, and caustics — making them one of the most impactful visual settings in the system.
Step-by-step
Select your BP_Riverology actor in the Outliner. In the Details panel, expand the Normal Maps section to reveal the wave normal parameters.
| Parameter | Default | Description |
|---|---|---|
| Wave Normals | T_Water_TilingNormal_With_Height_L | The normal map texture used for water surface detail. This texture tiles across the water surface and animates based on flow direction. |
| Fast Wave | 0.35 | Animation speed of the normal map. Higher values create faster-moving surface ripples. |
| Scale Wave | 0.2 | Tiling scale of the normal map texture. Lower values create larger wave patterns, higher values create smaller, more detailed ripples. |
| Normal Flatness | 0.75 | Controls the intensity of the normal map effect. 1.0 = flat water (no surface detail), 0.0 = maximum normal intensity. |
With the normal maps configured, the water surface displays realistic ripples and wave patterns that animate with the river flow.
The normal map affects multiple visual aspects:
- Reflections — Surface normals distort reflected sky and environment.
- Refraction — Underwater objects appear to shimmer and distort.
- Specular highlights — Sun and light reflections break into dynamic patterns.
- Caustics — Light patterns on the riverbed follow surface normal variations.
Adjust Normal Flatness to balance between calm water (higher values) and turbulent rapids (lower values).
Parameter Tuning Guidelines
| Scenario | Recommended Adjustments |
|---|---|
| Calm, slow river | Increase Normal Flatness to 0.85–0.95, decrease Fast Wave to 0.15–0.25 |
| Fast-flowing rapids | Decrease Normal Flatness to 0.5–0.65, increase Fast Wave to 0.5–0.7 |
| Wide river | Decrease Scale Wave to 0.1–0.15 for larger wave patterns |
| Narrow stream | Increase Scale Wave to 0.3–0.5 for smaller, detailed ripples |
| Stylized/cartoon water | Increase Normal Flatness to 0.9–1.0 for flatter appearance |
| Photorealistic water | Set Normal Flatness to 0.6–0.75 with Scale Wave at 0.15–0.25 |
Custom Normal Map Textures
You can replace the default normal map with your own texture. When creating custom normal maps for Riverology:
| Requirement | Specification |
|---|---|
| Format | Tangent-space normal map (RGB) |
| Tiling | Must tile seamlessly in all directions |
| Resolution | 1024×1024 or 2048×2048 recommended |
| Compression | Use TC_Normalmap compression setting |
| Color Space | Ensure texture is imported as Normal Map (not sRGB) |
To assign a custom texture, click the Wave Normals dropdown and select your texture from the asset picker, or drag a texture directly onto the slot.
Troubleshooting Common Issues
| Problem | Likely Cause | Solution |
|---|---|---|
| Water surface appears flat | Normal Flatness too high | Decrease Normal Flatness to 0.6–0.75 |
| Surface too noisy/busy | Scale Wave too high | Decrease Scale Wave to 0.15–0.25 |
| Waves move too fast | Fast Wave too high | Decrease Fast Wave to 0.2–0.35 |
| Waves appear static | Fast Wave too low | Increase Fast Wave to 0.3–0.5 |
| Visible texture tiling | Scale Wave too low | Increase Scale Wave or use higher-resolution normal map |
| Normal map not visible | Texture not assigned | Verify Wave Normals has a valid texture assigned |
| Incorrect normal direction | Wrong texture format | Ensure texture uses TC_Normalmap compression and is not sRGB |
Summary
In this guide, you learned how to:
- Configure wave normal texture — Assign and customize the normal map that defines water surface detail.
- Adjust animation speed — Control how fast surface ripples move with the Fast Wave parameter.
- Control wave scale — Set the tiling density to match your river's character.
- Balance normal intensity — Use Normal Flatness to dial between calm and turbulent water.
Normal maps are fundamental to water realism. Small adjustments to these parameters dramatically change the river's visual character, from mirror-smooth pools to churning whitewater rapids.