Part 7: REFLECTIONS

Before diving into reflections, let's create materials to see them clearly:

BP_LHT_RefReflections Blueprint: Create a new Blueprint with reference spheres:

1. Chrome — M = 1.0, R = 0.0, Base Color = white (pure mirror)
2. Rough Metal — M = 1.0, R = 0.5, Base Color = white
3. Glossy Plastic — M = 0.0, R = 0.1, Base Color = mid grey
4. Rough Plastic — M = 0.0, R = 0.8, Base Color = mid grey

🖼️Image placeholder: Reflections Comparison - Different Materials

Reflections show the environment on shiny surfaces. Two components determine reflections:

1. Metallic — Metal surfaces reflect 100% of their color as reflections
2. Roughness — How blurry/sharp the reflection appears

In Unreal, reflections can come from multiple sources:

1. Sky Light Cubemap

• The HDRI/captured environment provides reflection data
• This is why HDRI Size matters — too small = black reflections
• Lowest quality but always available

2. Reflection Captures (Baked)

• Sphere or Box Reflection Capture actors
• Captures environment at that point
• Static — must be rebuilt when scene changes
• Good for interiors with stable lighting

3. Screen Space Reflections (SSR)

• Reflects what's visible on screen
• Fast but limited — can't reflect off-screen objects
• Causes artifacts at screen edges

4. Lumen Reflections

• Ray traced reflections using Lumen's scene representation
• Dynamic, handles off-screen content
• More expensive but higher quality

5. Hardware Ray Traced Reflections

• True ray traced reflections
• Highest quality, most expensive
• Requires RT-capable GPU

Project Settings > Engine > Rendering > Reflections:
    Reflection Method: [None / Lumen / Screen Space]

Remember from Section 1: We set this to None initially so we could see the difference. Now enable it to see what reflections add.

In Post Process Volume:

Lumen Reflections:
    ☑ Enabled
    Quality: 0.5 - 1.0 (higher = better but slower)
    Ray Lighting Mode: Surface Cache (default) or Hit Lighting

Ray Lighting Mode:

• Surface Cache — Uses Lumen's cached surface data (faster)
• Hit Lighting — Evaluates lighting at ray hit point (more accurate, slower)

For highest quality reflections:

Project Settings > Engine > Rendering:
    ☑ Support Hardware Ray Tracing

Post Process Volume > Reflections:
    ☑ Ray Traced Reflections

When to use RT Reflections:

• Automotive visualization
• Architectural renders
• Product shots with chrome/glass
• When Lumen reflections aren't accurate enough