Geometry

How Houdini represents geometry and how to create and edit it.

Subtopics ¶

Understanding ¶

Working with objects
Primitives
Points and vertices
Geometry attributes

Describes how Houdini represents geometry using details, primitives, points, vertices, and attributes.
Groups
Volumes

Modeling ¶

Create geometry
Edit geometry
Edit components
Reselect geometry

In Houdini you can not only edit the parameters of a surface node, you can reselect the geometry the operation applies to.
Box up modeling
Curve up modeling
Mirror geometry across a symmetry plane
Repair polygonal models
Snapping, construction plane, and alignment
Trim NURBS surfaces

Terrain ¶

Building terrain with height fields

How to use Houdini’s height field tools to generate realistic terrain.
Realistic terrain with heightfields

A heuristic workflow using the heightfield tools, based on experience generating realistic-looking terrain.

Fracturing ¶

Destruction

How to break different types of materials.

Clouds ¶

Create a sky

How to create 2D and 3D cloud patterns using the Sky Field node.
Model hero clouds
Cloud rendering with volume ambient occlusion

Next steps ¶

Import geometry from other objects
Create, edit, and use Null objects
Geometry appearance editor

The appearance editor mode of the data tree pane lets you edit various controls for object viewport/rendered appearance in one place.
Locking geometry nodes

Guru level ¶

Packed primitives
Looping in geometry networks
Compiled blocks

You can mark a chain of compilable SOPs as a compiled block which can execute much faster in parallel.
Programmatic geometry with verbs

Many geometry (SOP) nodes allow you to use them in Python scripts to generate geometry programmatically.
Primitive Parametric Spaces (Implicit UVs)
Speed vs. reproducibility in Math Kernel Library

Some nodes use a library that gives a speed boost for floating-point operations but can make the output vary between different computers. You can control how much the library tries to guarantee reproducible results.

See also

Houdini 20.5

Getting started ¶

What’s new in Houdini 20.5

New features and changes in Houdini 20.5
Installation And Licensing

Installation and Licensing guide.
Basics

The basics of working with Houdini’s user interface.
Shelf tools

How to use and customize the icons on the shelf at the top of the main window.
Networks and parameters

How to use the network and parameter editors to work in Houdini.
Examples

Example files showing how different nodes work.
How to use the help

How to use the online help and document your own tools.

Using Houdini ¶

Geometry

How Houdini represents geometry and how to create and edit it.
Copying and instancing

How to use copies (real geometry) and instances (loaded or created at render time).
Animation

How to create and keyframe animation in Houdini.
Digital assets

Digital assets let you create reusable nodes and tools from existing networks.
Import and export

How to get scene, object, and other data in and out of Houdini.
MPlay viewer

Using Houdini’s stand-alone image viewer.

Character FX ¶

Character

How to rig and animate characters in Houdini.
Crowd simulations

How to create and simulate crowds of characters in Houdini.
Muscles and tissue

How to create and simulate muscles, tissue, and skin in Houdini.
Hair and fur

How to create, style, and add dynamics to hair and fur.
Feathers

How to create highly realistic and detailed feathers for your characters.

Dynamics ¶

Dynamics

How to use Houdini’s dynamics networks to create simulations.
Vellum

Vellum uses a Position Based Dynamics approach to cloth, hair, grains, fluids, and softbody objects.
Pyro

How to simulate smoke, fire, and explosions.
Fluids

How to set up fluid and ocean simulations.
Oceans and water surfaces

How to set up ocean and water surface simulations.
MPM

How to simulate different types of solid materials (such as snow, soil, mud, concrete, metal, jello, rubber, water, honey, and sand).
Destruction

How to break different types of materials.
Grains

How to simulate grainy materials (such as sand).
Particles

How to create particle simulations.
Finite elements

How to create and simulate deformable objects

Pipeline ¶

Executing tasks with PDG/TOPs

How to define dependencies and schedule tasks using TOP networks.
HQueue

HQueue is Houdini’s free distributed job scheduling system.
Houdini Engine

Documents the Houdini Engine C, Python APIs, and Houdini Engine plugins
Machine Learning

Houdini provides a platform for machine learning which supports synthetic data generation, preprocessing, training models, exporting trained models, and deploying trained models

Nodes ¶

OBJ - Object nodes

Object nodes represent objects in the scene, such as character parts, geometry objects, lights, cameras, and so on.
SOP - Geometry nodes

Geometry nodes live inside Geo objects and generate geometry.
DOP - Dynamics nodes

Dynamics nodes set up the conditions and rules for dynamics simulations.
VOP - Shader nodes

VOP nodes let you define a program (such as a shader) by connecting nodes together. Houdini then compiles the node network into executable VEX code.
LOP - USD nodes

LOP nodes generate USD describing characters, props, lighting, and rendering.
ROP - Render nodes

Render nodes either render the scene or set up render dependency networks.
CHOP - Channel nodes

Channel nodes create, filter, and manipulate channel data.
COP - Copernicus nodes

COP nodes provide real-time image manipulation within a 3D space.
TOP - Task nodes

TOP nodes define a workflow where data is fed into the network, turned into work items and manipulated by different nodes. Many nodes represent external processes that can be run on the local machine or a server farm.
APEX - APEX nodes

APEX nodes provide operations for building up the functionality of APEX graphs, which are used in KineFX to create character rigs and perform other geometry manipulation.

Scene building, Karma rendering, Image processing ¶

Solaris and Karma

Solaris is the umbrella name for Houdini’s scene building, look development, and Karma rendering tools based on the Universal Scene Description (USD) framework.
Copernicus

Houdini’s 2D and 3D GPU image processing framework.
Compositing

Houdini’s compositing networks let you create and manipulate images such as renders.

Mantra rendering and shading ¶

Mantra rendering

How to render images and animation with the Mantra engine.
Mantra materials

How to assign materials and create custom materials for shading.

Reference ¶

Menus

Explains each of the items in the main menus.
Viewers

Viewer pane types.
Panes

Documents the options in various panes.
Windows

Documents the options in various user interface windows.
Stand-alone utilities

Houdini includes a large number of useful command-line utility programs.
APIs

Lists all the reference documentation for the ways you can program Houdini.
Python scripting

How to script Houdini using Python and the Houdini Object Model.
Expression functions

Expression functions let you compute the value of parameters.
HScript commands

HScript is Houdini’s legacy scripting language.
VEX

VEX is a high-performance expression language used in many places in Houdini, such as writing shaders.
Properties

Properties let you set up flexible and powerful hierarchies of rendering, shading, lighting, and camera parameters.
Galleries

Pre-made materials included with Houdini.
Houdini packages

How to write and combine multiple environment variable definition files for different plug-ins, tools, and add-ons.
hwebserver

Functions and classes for running a web server inside a graphical or non-graphical Houdini session.

Licenses

Credits