Materials & surfaces

10:00 · Brief Surfaces tell the truth, light tells the time

A material isn't a color — it's a claim about physics. PBR (physically based rendering) means the renderer treats your surface parameters as measurements: how rough, how metallic, how the microsurface scatters light. Get the physics honest and the same material works at noon and midnight. Paint the lighting into the texture, and it works exactly once.

The PBR inputs that do the work

• Base color — the surface's actual albedo, with no lighting or shadows baked in. Real-world albedos are duller than beginners expect.
• Roughness — the single most expressive channel. Variation in roughness (fingerprints, wear, damp) is what makes a surface feel touched.
• Metallic — nearly binary: a thing is a metal or it isn't. In-between values are almost always a mistake.
• Normal — surface detail without geometry. Your scanned Fab assets carry excellent ones; your job is not to fight them.

UE 5.8's Substrate is the engine's newer material authoring model — built for layered, physically complex surfaces like car paint or frosted glass. We'll touch it where it helps, but the master-material-plus-instances discipline below is the workhorse either way: one parent graph, many instances, parameters instead of copies.

10:45 · Guided lab Dress and light the blockout

You work on your own Project 1 blockout today. By 4:00 it should have honest surfaces and one deliberate lighting scenario — built by hand, so you can judge what the agent proposes afterward.

1. Build one master material

   In your project's Content/Materials folder, create a material M_Master_Surface. In the material editor, wire texture parameters for base color and normal, and scalar parameters for roughness and a color tint. Parameters — not constants — are the whole point.

2. Derive instances

   Right-click the master → Create Material Instance. Make MI_ instances for your room's three or four dominant surfaces — floor, walls, one accent — using textures from your Fab assets or Fab's surface library. Tune each instance in its editor; note that nothing recompiles.

3. Apply and judge at eye height

   Assign the instances to your blockout geometry, then judge them in PIE at eye height, not from the editor's god view. Tiling scale reads completely differently at 170 cm.

12:00 · Workbench Practice, unhurried

No new material. You work on your own file while I circulate — this is the hour where the technique from the guided lab stops being something you watched and becomes something you can do.

1. Finish the lab on your own work

   The guided lab was built on the class example. Now do it on the piece you are actually submitting. That second pass is where it sticks.

2. If you fell behind, catch up here

   This is what the hour is for. Say so and I will come to you — do not spend it quietly stuck.

3. If you are ahead, go deeper

   Take the optional extensions from the lab, or push the piece further than the brief asks. Nothing graded depends on them.

4. Ask the AI TA anything

   The tutor on the course site is open all term for questions about how and why. It explains; you build. No agents in the work until Week 9.

1:15 · Crit / share One view, one hour

Everyone shows a single view of their room in the chosen lighting scenario and names the hour of day it claims to be. The room votes on whether it's telling the truth. Two weeks to Project 1 crit — from here on, everything is refinement.

Homework — due before Week 5

Resources

• UE 5.8 release notes — the Megalights and Lumen Lite sections are this week's primary reading.
• Epic Developer Community — Learning — the materials and lighting guided courses; both feed the Week 7 exam.
• Claude Code documentation — worth revisiting now that your prompts are getting art-directional.