Houdini 21.0 What’s new What’s new in Houdini 21

What’s new Muscles & Character Effects

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New Otis Solver

Note

These new Muscle tools use the Otis solver, the FEM-like muscle and tissue solver in SOPs. Please note that though this solver is a SOP node, it is not available in Houdini Core,

New Muscle Transfer workflow

  • New Deflate SOP to control how fatty regions influence muscle transfer.

Improved Muscle Activation workflow

  • New Muscle Auto Tension Lines SOP which procedurally generates one tension line per muscle.

  • New Muscle Tension Lines Activate SOP with a simpler and more powerful interface for controlling muscle activation. This node allows you to set multiple tension lines simultaneously and automatically applies the same settings to mirrored line. It also allows more control over the activation lengths.

  • Muscle Flex SOP improvements:

    • New parameter Match Tensions Lines by Name. If tension lines names match muscle_id they will be matched automatically. You don’t need to configure it in the parameter interface. A custom Muscle ID attribute can also be specified.

    • Now takes the muscletension activation attribute from the third input, created by the Muscle Tensions Lines Activate SOP, instead of manually setting activation ratios for each tension line on this node.

    • New Blend parameter which is useful for keying in activations gradually at the start of a simulation.

    • No longer defaults to outputting deformed muscles which increases performance and simulation times. New parameter to toggle on Deform Muscles which is necessary only when muscle ends are constrained to input animation.

CFX production-ready biped geometry and recipes

  • The new Test Geometry: Otto SOP is a realistic male character complete with a biped rig and anatomically-correct muscle and skeletal bone geometry. You can transfer his muscles and bones to your own human-like bipeds.

  • New Test Geometry: Otto Muscle Transfer recipe quickly transfers Otto’s fully modeled muscles to a biped character with matching topology. Also serves as a starting template to transfer custom muscle setups between similar characters. Designed to plug directly into the Test Geometry: Otto Muscle and Tissue Simulation recipe.

  • New Otis Muscle and Tissue Simulation recipe provides a generic simulation setup template for any character with custom muscle geometry. It’s ideal as a starting point for non-humanoid or stylized characters where the Otto’s muscle geometry cannot be transferred.

  • New Test Geometry: Otto Muscle and Tissue Simulation recipe is a complete muscle and tissue simulation setup configured specifically for Otto’s muscle geometry or Otto’s muscles transferred to another biped character.

Muscle geometry preparation nodes

  • New Muscle Adjust Volume SOP inflates or deflates static muscles with collisions. You can enforce a minimum thickness, constrain to skin geometry, or grow unconstrained.

  • New Muscle Deintersect SOP ensures that there are no intersections among muscles or between muscles and bones. This improves quality and performance of muscle simulations.

CFX Deformers

  • New Muscle Deform SOP deforms muscles using bone geometry. This includes options to solve muscles quasi-statically. The result produces volume-preserving muscle motion, without the need for a simulation.

  • New Skin Deform SOP deforms animated skin using simulated tissue, or animated muscles & bones. Easily control which regions to keep the incoming animation, such as face and hands, with a mask. Includes an option to compute procedural skin sliding, which in most cases removes the need for a skin simulation pass.

  • New Armature Capture SOP and Armature Deform SOP allow you to deform organic tissue repeatedly with skeleton poses using a quasistatic simulation. You can use these nodes to generate training data for an ML deformer and for other applications outside of ML.

  • Surface Deform SOP has faster piece handling.

Quality of life and performance improvements

General character effects and finalling

  • New Shot Sculpt SOP allows you to do finalling on animated or simulated characters using the toolset from the Sculpt SOP.

  • Attribute Paint SOP has the ability to rename painted masks.

  • New Separate Pieces SOP offsets individual pieces of geometry identified by a unique string or integer attribute so they no longer spatially overlap. This is useful for transferring attributes and performing other spatially dependent operations without the need for a for-each loop.

Grooming

  • The Guide Clump Center SOP creates a single representative curve for each clump in a groom. These center curves are typically used for visualization, simulation, or as control guides.

  • The Guide Find Strays SOP identifies guide curves that are isolated from others, which may need special treatment in certain hair and fur workflows.

  • The Guide Volume SOP constructs volumes from guide curves, producing outputs such as cross sections, shell surfaces, remeshed surfaces, or tetrahedral volumes.

  • The Guide Surface SOP positions points of a triangulated mesh along guide or fur curves. Note that the mesh itself is not generated by this node, but is expected on the second input. You typically create the mesh with the Guide Interpolation Mesh SOP.

  • The Guide Fill SOP enhances a mesh created by the Guide Interpolation Mesh SOP by generating additional guides at points without existing guide curves. This results in more complete guide coverage, simplifying subsequent grooming workflows and processing steps.

What’s new in Houdini 21