Houdini 20.0 Nodes Render nodes

Dem Bones Skinning Converter render node

Converts any non-changing topology deforming mesh sequence into a bone-based animation.

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Since 19.5

Dem Bones - © Electronic Arts 2019

This node is an implementation of Smooth Skinning Decomposition with Rigid Bones, an automated algorithm that extracts the Linear Blend Skinning (LBS) with bone transformations from a set of example meshes.

Skinning decomposition can be used in various tasks:


This node can only handle clean input data. For example, only one piece of connected geometry. If this node takes a really long time to process, then it may have gotten stuck while trying to find a solution. To fix this, set the Min Non-Zero Weights parameter to 1.


Save to Disk

Starts the skinning decomposition and exports the result to disk.

Output File

The path to which to save the FBX output.

Create Intermediate Directories

Create the directories in the FBX output path if they do not exist.

Conversion Settings

Input Animated Cache

Specifies the path to the Alembic geometry cache containing the animated mesh sequence to be converted to a bone-based animation.

Input Bindpose FBX

Specifies the path to the FBX file that contains the geometry’s rest pose.

Create Root

When on, updates the bind pose to regroup joints under one root.


Max Number of Bones

Specifies the maximum number of bones that can be generated.


Due to the possibility that more efficient solutions may be found during conversion, the actual output may be lower than the number specified by this parameter.

Solver Iterations

Global Iterations

Specifies the number of global iterations to be processed during the conversion. Functions as a scalar for the number of optimizations that have to be calculated. For more complex scenes, increase Global Iterations.

Error Tolerance

The algorithm keeps track of the decreasing errors during iterations, and will increment a counter if the reduction is less than the threshold specified by this parameter. This allows the algorithm to stop optimizing early if no improvement has been found after the number of iterations specified by the Patience parameter.


Specifies the number of iterations to wait before stopping early when no improvement has been found that is incrementally better than the threshold specified by the Error Tolerance parameter.

Splitting Iterations

Specifies the number of clustering update iterations that are applied on initalization.

Transform Iterations

Specifies the number of bone transformation update iterations per global iteration. DemBones performs multiple bone transform updates after each weights update.

Soft Constraints

Translations Affinity

Activates a soft constraint that forces bone translation that follows the centroid of the patch supported by that bone. Values greater than 0 turn on the soft constraint, whereas values less than 0 disable the soft constraint.

For many use cases, a value of 0 (no constraint) may be required. Whether or not to use higher values should depend on numerical stability and whether optimization can converge or not.


Specifies the the power used to compute the centroid of the patch. Higher values will move the centroid of the bones closer to the vertices with max weights (soft-max).


Weights Interations

Specifies how many weight updates to perform after each bone update. 1-5 iterations usually produce good results. These iterations are very expensive. As such, it is better to increase the Global Iteration than to increase the number of Weights Interations.


Controls the weights smoothness for the generated soft constraint.

Step Size

Specifies the step size of the Implicit Laplacian smoothing on the weights for the soft constraint.

Min Non-Zero Weights

Specifies the number of non-zero weights per vertex required for the conversion to succeed.


Bone-based animation data exported as an FBX file.

See also

Render nodes

  • Agent

    This output operator is used to write agent definition files.

  • Alembic

    Exports the scene to an Alembic archive. Alembic is a common exchange format for moving geometry and animation between different 3D software packages.

  • Archive Generator

    Generates disk-based archives which can be used by either mantra or RIB renderers.

  • Bake Animation

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  • Bake Texture

    Generates a texture map from one or more objects' rendered appearance.

  • Batch

    Renders the input ROP in a single batch job.

  • Channel

    The Channel output operator generates clip files from a particular CHOP.

  • Composite

    Renders images from a compositing network.

  • DSM Merge

    Merges two or more deep shadow/camera map files.

  • Dem Bones Skinning Converter

    Converts any non-changing topology deforming mesh sequence into a bone-based animation.

  • Dynamics

    Saves the state of a DOP network simulation into files.

  • Fetch

    Makes a dependency link to a ROP in a different network.

  • Filmbox FBX

    Exports entire scenes to FBX files.

  • Filmbox FBX Animation

    Export animation from geometry-based skeleton to an FBX file.

  • Filmbox FBX Character

    Export a skinned character with geometry-based skeleton to an FBX file.

  • Frame Container

    Prevents frame dependency changes in the contained nodes from affecting its inputs.

  • Frame Depedency

    Allows an output frame to depend on one or more input frames.

  • GLTF Character

  • Geometry

    Generates geometry files from a SOP or DOP network.

  • Geometry Raw

    Generates raw binary files from a SOP or DOP network.

  • HQueue Render

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  • HQueue Simulation

    HQueue, or Houdini Queue, is a distributed job scheduling system.

  • Hair Card Texture

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  • Karma

    Renders non-USD scenes using Houdini’s Karma renderer.

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  • Labs Flipbook Textures

    Renders, composites, and exports flipbook textures.

  • Labs JSON Exporter

    Export geometry attibutes to a JSON file.

  • Labs Marmoset Export

    The Marmoset Export ROP allows you to quickly generate an mview inside Houdini

  • Labs Niagara ROP

    Export point caches to be used with Unreal’s Niagara particle system.

  • Labs Sketchfab

    Uploads geometry to Sketchfab

  • Labs Vertex Animation Textures

    The Vertex Animation Textures ROP will export a mesh and a set of textures to be used with a shader for complex real-time effects, such as: soft-body deformation, rigid-body dynamics, dynamically remeshed geometries, and particle sprites.

  • MDD Point Cache

    This output operator is used to write an MDD animation file.

  • Mantra

    Renders the scene using Houdini’s standard mantra renderer and generates IFD files.

  • Mantra Archive

    Generates disk-based archives which can be used by mantra.

  • Merge

    Merges several render dependencies into one.

  • Net Barrier

    Blocks the ROP network until synchronization occurs.

  • Null

    Does nothing.

  • OpenGL

    Render an image using the hardware-accelerated 3D viewport renderer.

  • Pre Post

    Renders ROPs before and after a main job.

  • Shell

    Runs an external command.

  • Subnetwork

    The SubNetwork output operator provides an easy way to manage large number of output operators.

  • Switch

    Renders one of several inputs.

  • Tractor

    Tractor is a program shipped out with Pixar’s distribution of RenderMan.

  • USD

    Renders a LOP network out to one or more USD files. This node is available as render node or as a LOP.

  • USD Render

    Renders an output image from the stage generated by a LOP network.

  • USD Stitch

    Merges USD files representing individual frames by composing them.

  • USD Stitch Clips

    Merges multiple value clips representing individual frames.

  • USD Zip

    Assembles USDZ archive files from existing USD files.

  • Wedge

    Re-renders the same ROP multiple times with different settings

  • Wren

    This output operator is used to drive the Wren rendering program.

  • glTF