Your First Unity Surface Cache GI Preview Evening - URP Keep Hold 2026

If you are searching unity surface cache gi, you do not need another “Unity finally has Lumen” rumor thread. You need a Monday path: open a preview-capable Unity 6.x URP project, enable Surface Cache GI (SCGI) per Unity’s Getting Started guidance, light one small dynamic scene, write honest notes on diffuse-only limits and temporal stability, then decide keep (watch/preview) / hold (ship bake) / rewrite (wrong pipeline) before anyone deletes lightmaps on a production branch.

Surface Cache GI is Unity’s new URP realtime indirect diffuse lighting path. Unity’s lighting team invited public preview testing on Discussions ahead of a 6.7 LTS expectation (not a guarantee). GameFromScratch summarizes the design: patches in position+direction space, hardware ray tracing when available, otherwise compute software RT. Unite Seoul’s Unity 7 roadmap also calls out realtime GI via Surface Cache GI as a graphics pillar—roadmap marketing is not the same as “ship tonight on alpha.”

Who this is for: creators evaluating whether to leave baked GI; TDs comparing SCGI to Lumen / Godot SDFGI honesty; leads who need diligence language for preview vs production lighting.
Time: about 60–90 minutes for first enable + smoke + receipt.
Honest limit: preview/alpha maturity; diffuse-only today (pair reflection probes/SSR for specular); temporal flicker reported by community; not a drop-in “delete all lightmaps and ship Steam tomorrow” button.

Non-repetition: This is not the Unity 7 roadmap keep/hold (engine pillars / MCP / CLI). It is not Fast Enter Play Mode 6.6 (Play mode statics). It is not Unity CLI first session. It is not Programming Fest. Same Unity family—URP Surface Cache GI first preview evening.

Why this matters now

1. Unity publicly invited SCGI testing. The Surface Cache GI Preview thread is the feedback lane before a hoped-for 6.7 readiness—exactly when indies should learn limits, not invent marketing claims.
2. Unity 7 marketing raised the GI stakes. Unite Seoul lists Surface Cache GI under breakthrough graphics.Unity News Roadmap ≠ preview maturity—keep them separate in partner decks.
3. URP finally has a first-class realtime diffuse GI story. That closes a long SERP gap vs Unreal Lumen and Godot SDFGI—but only if you respect diffuse-only and stability tradeoffs.GameFromScratch
4. SERP is forum + announce heavy. Indies still need a first-evening enable path, keep/hold table, bake fallback, and receipt—not another “patches are 5D” restatement alone.

Parent Unity search demand stays enormous. The preview thread’s large reply volume shows real community pressure for honest enablement guides.

What Surface Cache GI is (and is not)

Unity frames SCGI for dynamic lights/geometry, procedural content, time-of-day, and avoiding long bake waits—while still asking for community bug reports before release.Preview thread

Keep / hold / rewrite — SCGI preview

Print the table. Circle one cell.

Beginner path - one evening SCGI smoke

Prerequisites

• Unity 6.x build that includes Surface Cache GI preview bits (confirm live Getting Started / package notes—versions move).
• A URP project you can break (not your Steam ship branch).
• GPU notes: does this machine have hardware RT?
• 60–90 minutes.

Step 1 - Branch and snapshot

1. Create git branch preview/scgi-smoke (or duplicate the project).
2. Screenshot current lighting setup (lightmaps on/off, APV, probes).
3. Write baseline_fps on a known camera path if you have a simple HUD timer—optional but diligence-friendly.

Step 2 - Enable Surface Cache GI (follow live docs)

Unity’s Getting Started (linked from the preview thread) is authoritative. Typical pattern reported by coverage:

1. Add the SURFACE_CACHE (or live-documented) scripting define in Player/Project Settings.
2. Add the Surface Cache Global Illumination renderer feature to your Universal Renderer Data.
3. Configure volume / radius / quality knobs per Getting Started—start conservative.
4. Restart Editor if defines require it.

If menus differ, stop and quote the live doc—do not invent menu paths from memory.

Step 3 - Build a tiny dynamic light scene

Minimum scene:

1. Closed room with a few colored walls.
2. One movable point light or day/night directional change.
3. One dynamic prop you can move at runtime (or a simple transform script).
4. A camera fly that shows indirect bounce on walls.

Observe:

• Does indirect light update when the light moves?
• Flicker / ghosting when the camera moves?
• Cost spike when turning SCGI off vs on?

Step 4 - Honesty checks (diffuse + stability)

Community reports often praise performance while flagging temporal stability / flicker—treat that as a gate, not a surprise.Discussions

Step 5 - Keep / hold decision sentence

Examples:

• Keep (preview): “SCGI enabled on preview branch; bake remains ship lighting until 6.7 + stability green.”
• Hold: “Flicker/cost fails targets; revisit after next preview drop.”
• Rewrite: “HDRP/custom pipeline—wrong article path; evaluate differently.”

Common beginner mistakes

• Enabling SCGI on the release branch first.
• Deleting lightmaps after one pretty screenshot.
• Comparing URP SCGI to Lumen specular quality without probes.
• Ignoring software RT cost on Deck/iGPU.
• Quoting Unity 7 marketing as if preview is LTS.
• Skipping a receipt (“it worked on my machine”).

Developer path - gates, comparisons, receipt

P1–P6 keep/hold gates

Latch scgi_preview_ok only when P1–P6 pass.

Sample receipt JSON

{
  "schema": "unity_surface_cache_gi_preview_receipt_v1",
  "date": "2026-07-25",
  "unity_version": "6000.x.y-preview-or-alpha",
  "pipeline": "URP",
  "branch": "preview/scgi-smoke",
  "sources": [
    "https://discussions.unity.com/t/surface-cache-gi-preview/1720494",
    "https://unity.com/news/unity-7-roadmap-revealed-at-unite-seoul"
  ],
  "define_enabled": true,
  "renderer_feature_added": true,
  "hw_ray_tracing": true,
  "dynamic_light_smoke": true,
  "temporal_stability": "acceptable_preview|fail",
  "diffuse_only_acknowledged": true,
  "specular_plan": "reflection_probes",
  "ship_lighting_owner": "baked_lightmaps",
  "decision": "keep_preview_hold_ship",
  "gates": {
    "P1_sources": true,
    "P2_enable": true,
    "P3_smoke": true,
    "P4_limits": true,
    "P5_fallback": true,
    "P6_receipt": true
  },
  "scgi_preview_ok": true,
  "operator": "session-owner-handle"
}

Comparison table - SCGI vs cousins

Workflow - when to keep bake as ship lighting

Keep bake/APV as the release path when any are true:

1. You need specular GI as a marketing hero without a probes/SSR plan.
2. Temporal stability fails your camera language (cutscenes, slow pans).
3. Target devices lack HW RT and swRT cost breaks frame budget.
4. Certification/partner builds forbid preview packages.
5. Art leads cannot tolerate patch cascade artifacts.

SCGI can still be a preview R&D win on a side branch.

Workflow - Unity 7 vs 6.7 expectation hygiene

Unite Seoul markets Surface Cache GI under Unity 7 graphics.Unity News Discussions aim SCGI readiness around 6.7 expectations without hard guarantees.Dynamic GI roadmap

Partner language:

We are evaluating Surface Cache GI on a preview branch. Ship lighting remains baked until version X and stability gates pass. Unity 7 roadmap GI is tracked separately from this preview.

Pair with your Unity 7 roadmap playbook for MCP/CLI pillars—not lighting smoke.

Workflow - performance notes

Community feedback often calls SCGI surprisingly cheap on capable GPUs while complaining about stability more than raw ms.Preview thread Your job:

1. Measure your scenes, not Twitter ms quotes.
2. Test with HW RT on and off if possible.
3. Log Deck/mobile separately—or mark N/A.
4. Do not ship “1.5ms everywhere” claims from someone else’s APU test.

Company / diligence language (paste-ready)

Q: Are we shipping Surface Cache GI?
A: Preview decision: keep_preview_hold_ship / hold / rewrite. Unity version: . Branch: . Receipt attached.

Q: Is this the same as Lumen?
A: No. SCGI is Unity URP realtime diffuse GI with different design goals (reach/performance). Specular needs probes/SSR or later Unity work.

Q: Does Unity 7 announcement mean we can delete lightmaps?
A: No. Roadmap messaging ≠ preview maturity. Bake remains ship default until gates pass.

Q: What is the risk?
A: Alpha/preview bugs, temporal instability, diffuse-only look, device cost variance. Mitigated by throwaway branch + bake fallback.

Sample evening timeline (strict)

Troubleshooting matrix (night-one)

Studio ownership checklist

1. Preview branch owner: ___
2. Lighting TD: ___
3. Ship bake owner: ___
4. Device matrix owner (PC/Deck/mobile): ___
5. Receipt path: receipts/unity_surface_cache_gi_preview_receipt_v1.json

Quality knobs - what to turn first (preview)

Unity exposes quality/performance tradeoffs (patch size, cascades, sample counts—confirm live Getting Started names). Night-one rule:

1. Start medium/default knobs—do not max everything on first enable.
2. If flicker dominates, reduce aggressiveness before declaring SCGI “broken.”
3. If cost dominates, lower far cascades / radius before blaming URP itself.
4. Log every knob change in the receipt—otherwise next week’s “it regressed” is unfalsifiable.

Do not publish a Steam trailer claiming “fully dynamic GI” until your art lead signs the stills.

Art lead checklist (paste)

1. Hero still with SCGI on: ___
2. Same camera with bake: ___
3. Specular plan (probes/SSR): ___
4. Acceptable flicker on slow pan: yes/no
5. Color grading still matches brand bible: yes/no
6. Decision: keep_preview / hold_ship / rewrite

Any “no” on ship-critical rows → bake stays king.

HDRP and custom pipelines

This evening is URP Surface Cache GI. If your project is HDRP or a custom SRP:

1. Do not force URP conversion tonight for FOMO.
2. File decision: rewrite with pipeline name.
3. Track Unity’s live docs for whether SCGI expands—do not invent HDRP parity.

Sample Discord brief (paste, then edit)

We enabled Surface Cache GI on branch preview/scgi-smoke only. It is Unity URP realtime diffuse GI in preview—not Lumen, not a lightmap deletion party. Ship lighting stays baked until stability + version gates pass. Owner: ___. Receipt filed.

Device matrix worksheet

Blank cells that matter for your SKU → hold ship claims.

After tonight - what keep unlocks next sprint

1. Weekly re-test on newest preview drop.
2. One hero scene comparison: bake vs SCGI stills for art lead.
3. Optional feedback post on Unity Discussions with repro steps.
4. Keep Unity 7 / FEPM / CLI workstreams separate in the roadmap.

Feedback hygiene - how to report upstream without drama

Unity asked for preview feedback. Useful reports include:

1. Exact Unity version string and URP package versions.
2. HW RT on/off.
3. Minimal repro scene (strip art).
4. Video of flicker or incorrect bounce.
5. What you expected vs what happened in one sentence.

Useless reports: “looks bad,” “not Lumen,” “fix my ship build.” Preview bandwidth is finite—spend it on falsifiable bugs.

When SCGI is the wrong evening entirely

Sit this playbook out (decision rewrite or schedule later) if:

1. You ship HDRP-only and cannot spare a URP spike.
2. Your art bible requires specular GI as the hero without a probes plan.
3. You are mid-cert with a frozen editor—no preview packages allowed.
4. The team cannot staff a second lighting owner for bake fallback.

Wrong evenings create fake “we tried realtime GI” myths. Better to wait for a green version gate.

Key takeaways

• unity surface cache gi is Unity URP’s realtime indirect diffuse GI preview—not automatic Lumen parity.
• Public testing is invited on Unity Discussions ahead of a 6.7-class expectation.
• Unity 7 roadmap GI callouts are separate from tonight’s alpha contract.
• Enable on a throwaway branch; keep bake as ship lighting until gates pass.
• Plan specular via probes/SSR; SCGI is diffuse-first today.
• Treat temporal stability as a hard gate.
• Measure cost on your targets—especially without HW RT.
• Use P1–P6 and a dated receipt.
• Do not delete production lightmaps after one pretty screenshot.
• File bugs upstream with repros—preview exists for that.

FAQ

What is Unity Surface Cache GI?

A URP feature that computes realtime indirect diffuse lighting using a world-space surface cache of patches, with hardware or software ray tracing backends, aimed at dynamic lighting/geometry without traditional bake waits.Preview GameFromScratch

Is Surface Cache GI ready to ship?

Treat it as preview/alpha until your Unity version and stability gates say otherwise. Unity discusses a 6.7 readiness expectation without hard guarantees.

Does it replace lightmaps tonight?

For production: usually no. Use SCGI on a preview branch; keep bake/APV as the ship path until you pass P1–P6.

How is this different from Lumen?

Different engine and design goals. Unity emphasizes reach/performance and currently focuses on diffuse GI; Lumen is a different Unreal stack with different cost/quality tradeoffs.

How does this relate to the Unity 7 roadmap?

Unity 7 marketing highlights Surface Cache GI as a graphics direction. That does not make today’s preview LTS-ready. See the Unity 7 roadmap playbook for pillar decisions.

What about specular reflections?

Plan reflection probes and/or screen-space techniques. Do not expect full specular GI from SCGI alone today.

What scripting define should I add?

Follow the live Getting Started doc linked from Unity’s preview thread. Community write-ups often mention a SURFACE_CACHE define, but menu names and defines can change between preview drops—quote your doc version in the receipt.

Can I use SCGI with procedurally drawn meshes?

Unity’s preview materials discuss limitations (including some procedurally drawn / indirect draw cases). Verify against current docs before promising SCGI on GPU-driven foliage systems.

Related reading

• Unity 7 Roadmap - What Indies Should Decide After Unite Seoul 2026 — pillar roadmap; GI is one graphics line
• Unity Fast Enter Play Mode in 6.6 - CoreCLR Prep Playbook for Indies 2026
• Unity 6.6 LTS Upgrade Safety Sprint - Step-by-Step Migration Playbook for Small Teams 2026
• How to Use Unity CLI - First Agent Safe Editor Session 2026
• Unity MCP with Cursor - First Safe Editor Bridge Session 2026
• Unreal Engine 6 Roadmap - What Changed for Indie Devs in 2026
• Steam Programming Fest 2026 - Themed Sale Discount Playbook for Indies — different domain

Official and useful sources

• Unity Discussions - Surface Cache GI Preview
• Unity News - Unity 7 Roadmap at Unite Seoul
• GameFromScratch - Unity Getting Real-Time Global Illumination
• Unity Discussions - Dynamic GI Roadmap feedback