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Tips For Production Use

Workingreference~6 min readreviewed 2026-07-05

Simplygon does exactly what you tell it, which is both the point and the trap. Bad inputs and vague targets get processed just as obediently as good ones. These are the rules I wish someone had handed me before the first "why does LOD2 look like melted cheese" bug report.

01Choose The Process By Bottleneck

Start with the cost you need to remove. A mesh with too many triangles, a kitbash prop with too many materials, and a city block with too many hidden interior faces are three different problems.

Problem Try First Check Before Shipping
Too many triangles on a normal propTriangle reductionSilhouette, hard edges, normals, UV seams.
Close-up editable or deforming topologyQuad reductionTopology flow, deformation, smoothing.
Messy scan or proxy/HLOD assetRemeshingBaked material fidelity, holes, silhouette.
Too many separate objectsAggregationPivot needs, collision, occlusion, naming.
Too many material slotsMaterial mergingAtlas resolution, channel mapping, shader features.
Hidden geometry inside clustersVisibility cullingCamera coverage and occluder setup.
Very distant vegetation or propsBillboard or impostorView-angle popping, opacity, lighting response.
Far skeletal LOD is expensiveBone reductionAnimation deformation, attachments, ragdoll constraints.
good default

Setting this up fresh? Start with just two presets - one gentle reduction, one material merge - and resist the urge to ship all eight methods at once. Add remeshing, visibility culling, and impostors once you can actually measure whether they're helping. Two presets people trust beat eight presets people fear.

02Set Targets Artists Can Understand

You get to enjoy the raw SDK settings - artists shouldn't have to. A good tool speaks intent ("Far LOD", "merge this prop"), and quietly maps that to whichever target type actually fits. Nobody painting a character wants to learn what "max deviation" means, and they shouldn't need to. For reference, the four target types and where each earns its keep:

  • Triangle ratio: good for predictable test passes and simple batch processing.
  • Triangle count: good when a platform budget gives you hard numbers.
  • On-screen size: good for LOD chains because the target relates to perceived screen coverage.
  • Max deviation: good when silhouette error matters more than a fixed triangle count.

Build presets around the review language your team uses:

Preset Likely Settings Review Question
Close LODMild reduction, preserve normals/materials.Can a player notice the switch?
Mid LODScreen-size reduction, maybe material simplification.Does the silhouette read correctly?
Far LODAggressive reduction or remesh.Does it hold up in motion?
ProxyRemeshing plus material casting.Does the baked proxy match the cluster from gameplay distance?
Draw-call mergeAggregation plus material merge.Did draw calls drop without losing shader-critical features?

03Treat Materials As First-Class Data

A lot of disappointing Simplygon results are material problems, not triangle problems. A reduction can look great in gray shaded mode and still fail because roughness, normals, opacity, vertex colors, or custom shader data got lost.

  • List required channels per asset type before creating casters.
  • Use consistent channel names across exporters, DCCs, and engine importers.
  • Test tangent-space normal baking on assets with hard edges and mirrored UVs.
  • Keep hero materials separate when shader features can't be baked safely.
  • Use multiple output materials if one atlas would become too large or too blurry.
  • Compare material count, texture memory, and shader complexity before and after processing.
caster checklist
REQUIRED_CASTERS = {
 "static_prop": ["Diffuse", "Normals", "Roughness", "Metalness"],
 "foliage": ["Diffuse", "Normals", "Opacity"],
 "emissive_prop": ["Diffuse", "Normals", "Emissive"],
 "vertex_color_asset": ["Diffuse", "Normals", "VertexColors"],
}

04Visibility Settings Need Real Cameras

Visibility culling and visibility-weighted reduction are only as good as the view data you give them. A pretty screenshot camera is not gameplay coverage.

  • Use gameplay camera paths, not marketing cameras, for visibility decisions.
  • Keep occluder selection sets explicit and reviewable.
  • Don't cull geometry destructively until you know all traversal paths and cinematic cameras.
  • For open-world assets, build separate presets for player-height, aerial, cinematic, and map-view cameras if needed.

05Characters Need Animation Review

Character LODs are not done just because the bind pose looks fine. Skinning, blend shapes, modular seams, attachments, cloth, and extreme poses all need review.

  • Test reductions on idle, locomotion, attack, emote, facial, and extreme-pose clips.
  • Preserve important seams between modular parts, especially heads, hands, armor, and clothing.
  • Use bone reduction carefully. Far LODs can use fewer bones, but socketed props and gameplay attachments may depend on specific joints.
  • Check normal and tangent changes on skin under animation, not only in a static viewport.
  • Keep a per-character visual regression set: close camera, mid camera, far camera, and silhouette-only view.

06Batch Safely

Batch processing is where Simplygon becomes pipeline infrastructure, and where tiny assumptions can turn into hundreds of broken assets. Build the batch runner like something people will depend on.

Feature Why It Matters
Per-asset loggingYou need to diagnose one failed source without rerunning the whole library.
Stable output pathsDownstream importers, diffs, and build systems need predictable locations.
Nonfatal failuresOne bad mesh shouldn't block every unrelated asset in a library pass.
Pipeline versioningResults must be traceable to a specific preset and SDK version.
Summary reportsBefore/after triangles, materials, textures, warnings, and processing time reveal whether the batch helped.
Review samplingRandomly inspect outputs from every batch, plus all assets with warnings.

07Review With Before-And-After Numbers

Visual inspection matters, but it's not enough. Every processed asset should carry a small report.

  • Original and processed triangle count.
  • Original and processed material count.
  • Output texture count, dimensions, and estimated memory.
  • Processing preset and SDK version.
  • Warnings and errors from the Simplygon log.
  • Image or viewport captures from standard review angles.
senior ta habit

Keep the first version of every preset conservative. Push harder only after you have review captures and runtime numbers that justify it.

08Troubleshooting Bad Results

Symptom Likely Cause Try
Silhouette collapsesTarget is too aggressive or wrong stop condition.Use max deviation or larger on-screen size; preserve border edges.
Normals look brokenBad source normals, hard edges, tangent-space mismatch.Validate normals, bake normal channel, check engine tangent basis.
Textures are blurryAtlas resolution too low or too many materials merged into one map.Increase texture size or split into multiple output materials.
Opacity foliage failsOpacity channel was not baked or alpha testing differs in engine.Add opacity caster and test the engine material path.
Remesh has holesSource mesh has open surfaces or hole-filling is not configured.Clean source, adjust hole filling, inspect remesh settings.
Character seams openModular parts were reduced independently or seam locks were missing.Process modules together or add seam preservation rules.
LOD pops badlyTargets too far apart or materials change too much between LODs.Add intermediate LOD, reduce material changes, review transition distance.
Batch output is inconsistentMixed source scale, transforms, or material conventions.Normalize inputs and validate before processing.