Retargeting: bone maps, rest poses and motion checks

What shared animation requires

Identical bone names do not make two skeletons compatible. Hierarchy, reference pose, axis orientation, proportions and animation-track paths can differ. Retargeting coordinates these data; renaming alone does not fix everything else.

Bone Rest is a bone's reference transform. In Skeleton3D, local Bone Pose includes its position relative to the parent bone: it is not an extra offset automatically multiplied by Rest again. ResetBonePose() restores the local pose from Rest. Do not transfer formulas for a relative Rest offset without checking.

Prepare the source and target skeletons

Import each character separately and verify its own animations first. A skinning/export failure before retargeting is not fixed by a name map.
Open advanced model-import settings and select Skeleton3D. Assign a BoneMap in Retarget.
Assign a profile. For a standard humanoid use SkeletonProfileHumanoid; other structures need an appropriate SkeletonProfile.
Check every important mapping: profile bone → source skeleton bone. For example, Hips → Pelvis. Editor name suggestions require review, especially left/right sides, spine and parent relationships.
Configure a consistent target naming scheme and skeleton paths for models sharing one AnimationLibrary. Check track paths and the skeleton's unique name if used.

A BoneMap resource by itself neither renames nor reposes bones in a live Skeleton3D. Assigning Profile in C# does not automatically inspect an arbitrary skeleton. Duplicate assignments to one source bone are possible—correct them before judging motion.

Choose reference-pose handling

The current importer provides retarget/rest_fixer/retarget_method:

Method	Purpose and check
None	Do not perform the selected Rest conversion through this method; check other enabled import operations separately
Overwrite Axis	Align reference axes with the profile. Compare deformation and orientation after reimport
Use Retarget Modifier	Use the built-in modifier/original-skeleton workflow. It requires consistent bone names; enable renaming and inspect warnings

These are built-in importer options. Selecting a modifier does not guarantee correct results for every rig. Retain the source model and settings; compare methods on the same animation, changing one parameter at a time.

Settings that affect the result

Setting	What matters
Apply Node Transforms	Applies tree transforms during skeleton preparation. Check scale, rotation and neighboring objects, not just the character at rest
Normalize Position Tracks	Normalizes position tracks against reference height; MotionScale participates in movement scaling. Does not guarantee elimination of foot sliding
Remove Tracks → Except Bone Transform	Can remove accessory animation and other required tracks; inspect clip contents before enabling
Remove Tracks → Unimportant Positions	Removes some position tracks while retaining those important to the profile. Assess proportions and motion transfer
Remove Tracks → Unmapped Bones	None, Remove and Separate Library options, rather than a simple flag. Check tails, hair and additional bones
Fix Silhouette	Adjusts toward the profile pose. Inspect shoulders, elbows, knees and feet; large silhouette differences can require source edits

The internal apply_node_transforms key and some labels use Node; this is an importer setting name, not a separate gameplay object model. Labels and values can be localized in the interface.

Verify after reimport

Play the same clip on the source and target characters. Check rest, walking, turns and extreme limb poses. Separately inspect hip height, root movement, foot contacts, accessories and tracks outside the skeleton.

Symptom	Check
Clip does not move the character	Skeleton3D/bone track paths, AnimationLibrary, naming scheme and renaming
Bones bend in the wrong direction	Body sides, parents, Rest and profile axes
Proportions changed	Position tracks, normalization, tree transforms and scale
Accessories or their motion disappear	Track removal and unmapped bones
Modifier breaks motion	Bone renaming, import warnings and track paths

See advanced model settings for general import actions. A correct name map is necessary; deformation and motion quality must be checked on the actual character.