Free online FBX to BVH converter

A legacy motion-capture application, avatar system, or animation tool may require BVH when the supplied character motion is in FBX. The conversion transfers an evaluated skeleton and its sampled animation; it does not transfer the FBX character model or scene.

What the FBX format is

FBX is Autodesk's proprietary 3D interchange format for scenes, characters, geometry, skeletal rigs, skin weights, materials, cameras, lights, blend shapes, constraints, and animation. Maya, 3ds Max, MotionBuilder, Blender, Unity, Unreal Engine, and motion-capture pipelines commonly import or export it.

An FBX file can contain several armatures, animation takes, actions, controllers, IK systems, nonuniform scale, and facial animation. Its exact contents depend on the exporting application and export settings. These scene and rig features must be reduced to one evaluated bone hierarchy and baked motion before a reliable BVH export.

What the BVH format is

BVH means Biovision Hierarchy. It is a plain-text motion-capture format with a hierarchy section and a motion section. The hierarchy defines joints, fixed offsets, and channel types; the motion section stores the frame count, frame time, and per-frame channel values, normally root translation plus Euler rotations.

BVH contains skeletal motion only. It has no polygon mesh, texture, material, skin weight, camera, light, facial blend shape, IK target, or constraint data. Its readable structure and small files suit legacy mocap software, research tools, animation tests, and virtual-character applications. BVH does not define one universal humanoid skeleton, naming scheme, unit, or axis convention.

Converting with Blender

Blender is a practical free desktop option because it can import FBX, bake evaluated animation, retarget motion with suitable rig tools, and export BVH through its motion-capture extension.

1. Import the source with File → Import → FBX (.fbx). Keep the armature and animated objects; remove unrelated scene content only if it makes selection easier.
2. Identify the armature that carries the required motion. If the FBX contains several actions, takes, NLA strips, or characters, select the action and frame range that should be exported. Play the timeline to confirm that Blender evaluates the intended motion.
3. Set the scene start and end frames to the exact segment required by the receiving application. Exclude calibration poses, unwanted T-pose frames, and trailing still frames when appropriate.
4. Retarget the animation before exporting if the destination requires a different skeleton, joint names, proportions, or hierarchy. BVH export does not automatically convert an arbitrary control rig into a humanoid template.
5. Bake constraints, IK, drivers, animation layers, and procedural controls onto the deform bones. In Pose Mode, use Pose → Animation → Bake Action; enable Visual Keying so Blender records the evaluated pose. Use Clear Constraints only on a duplicate or when the original controls are no longer needed.
6. Select the armature and choose File → Export → Motion Capture (.bvh). If the command is unavailable, enable Blender's BVH or motion-capture extension from Edit → Preferences → Get Extensions or Add-ons, depending on the Blender version.
7. Set the export frame range, sampling or baking options, scale, forward and up axes, and root-translation behavior. Export one armature to a file such as walk_cycle.bvh. Use root translation only when that matches the destination's convention; some workflows keep the root fixed and expect locomotion in the hips.
8. Open the result in the target software and inspect the first and last frames, facing direction, floor height, root movement, frame timing, and limb orientation. Adjust axes, scale, retargeting, or the frame range and export again if needed.

For production motion-capture cleanup and retargeting, Autodesk MotionBuilder can import the FBX, characterize or retarget the actor, plot the final result onto a destination skeleton, and export the baked motion as BVH. For a one-off conversion without installing software, the free converter on 101convert.com can process an FBX file; verify the downloaded BVH in the destination application because automated conversion cannot infer every custom rig mapping.

Compatibility and quality limits

• Only the exported hierarchy and sampled motion survive. Keep the FBX if the mesh, materials, skinning, facial animation, cameras, lights, or original control rig is still required.
• Export one character hierarchy at a time. BVH normally describes one root hierarchy, so scenes containing multiple characters or unrelated skeletons must be separated.
• Rig controls are not deform bones. IK targets, pole controls, constraints, and custom controllers are normally omitted unless their visible result is baked onto the exported joints.
• Axis and unit settings are not universal. A mismatch can produce a sideways, mirrored, inverted, or incorrectly sized character. Check the receiving application's up axis, forward axis, unit scale, root-joint expectation, and frame rate.
• Rotation conversion can alter motion. FBX may use quaternion interpolation or different Euler rotation orders, while BVH stores declared Euler channels such as Zrotation Xrotation Yrotation. Fast rotations can produce angle wrapping, discontinuities, or gimbal artifacts after resampling. Inspect shoulders, wrists, hips, and turns.
• Joint names and hierarchy may require retargeting. A file can load successfully while still needing manual mapping for hips, spine, limbs, hands, and feet. Do not edit joint order or channel columns in the text unless the hierarchy and motion layout are updated together.
• Animation is required for meaningful motion. A static FBX can produce a BVH hierarchy, but it cannot produce useful movement without keyed or baked skeletal animation. Facial blend shapes and other non-skeletal animation require a separate workflow.