Houdini 20.0

Marker visualizer

Visualizes attributes using various markers and labels.

See visualizers for more information.



Determines the style of visualization.


Shows attribute values as a label next to each element.

Element index

Shows each element’s index number as a label next to the element.

Point trail

Draws a line from the element’s location to the point contained in an attribute value. For example, visualizing the contents of a rest attribute would draw lines from the current point positions to their rest positions.

Vector trail

Draws a line from the point based on a vector attribute value’s direction and length.


Same as “vector trail” but draws the line gradient in the opposite direction.


Draws a small set of axes at each element to visualize a matrix or quaternion attribute.

The attribute must have either:

  • Nine (or more) components, in which case components 0-2, 3-5, and 6-8 are treated as the first, second, and third vector.

  • Four components, in which case it is treated as a quaternion.


Whether to visualize a point, primitive, vertex, or detail attribute.

Common parameters


When Visibility is “Near pointer”, Houdini projects a ray under the mouse pointer to the closest point, then displays markers on elements within this world space distance of that point.


The geometry to visualize on. This can be a group name or a space separated list of group names and/or component numbers. You can use expressions such as 10-30:3 to specify every third component from 10-30. See groups for more information.


Name of the attribute to visualize.


When the attribute is drawn in the viewport for each element.

Always Visible

Draw the marker on every element. If the geometry has a large number of densely-packed elements, you may want to use one of the other options to reduce clutter.

Only on Selection

Only draw the markers on the selected elements.

Near Pointer

Only draw markers on elements within a certain (world space) distance of the point under the mouse pointer. It projects a ray under the cursor onto the closest geometry, finds the (X,Y,Z) world space point of that intersection, then shows markers whose anchors are within that distance in 3D space. It should give you a small circular window effect.

Under Pointer

Only draw marker on the single element the mouse pointer is on.


Only draw makers on elements of a group given by a group expression.

Text/Element index

Text Color

The color of the labels.

Font Size

The size of the labels. “Guide font size” uses the size set on the Guides tab of the viewport display options window.

Point trail

Marker Color

Color of the points drawn at the attribute positions.

Trail Color

Color of the lines from the current position to the attribute positions. You can use the color’s alpha channel to make the lines semi-transparent.

Point Size

Radius of the point markers.

Vector/Vector trail

Length Scale

Allows you to scale the lines length up or down. This lets you make long lines shorter to reduce clutter, or make short lines longer to be more visible.

Normalize vectors

Normalize the values to the 0-1 range for display.

Show Arrow Tips

Draw a small barb at the end of each line.


Fixed color

Color all quills using the same color.

Vector values

Color the quills according to the vector values.

Other attribute

Color the quills using the value of another attribute.

Fixed color

Marker Color

Color of the lines drawn from the element based on the attribute vector.

Vector values/vector directions

Color mapping

How to display scalar data as colors. Choose a preset color ramp, or choose “Custom” to get a ramp control.


To map attribute values onto the ramp, Houdini needs to know the full range of possible values so it can scale that range onto the range of the ramp.


Looks at the actual values of the attribute in the visualized geometry and picks the minimum and maximum.

Min and Max

Allows you to manually specify min and max values. This can be useful when there’s a “natural” range of values larger than what’s currently in the geometry. You can also use a narrower range than what’s currently in the geometry as a way of highlighting values outside the range (see the Out of range values paramter).

Center and Width

Like Min and Max, except you specify a center value and the width of the range around that value.

Out of Range Values

How to color values outside the given range, when Range is “Min and Max” or “Center and Width”.

Roll Cyclically

Color the value as if the ramp repeated endlessly forward and backward.

Black Out

Color out of range values black.

Clamp to Edge Values

Use the first color in the ramp for values less than the range, and the last color in the ramp for values greater than the range.

Treat As Scalar

Convert vector attribute types (with more than one component) to a single value. This enables a menu for choosing how to convert the values.


How to convert multi-component values to a single number, when Treat as scalar is on.


Pick one of the components.

Component Abs.

Pick one of the components, and use its absolute value.

Component Sum

Sum up the component values.

Component Abs. Sum

Sum up the absolute values of the components.


Use the length of the vector.

Length Squared

Use the square of the length of the vector.

Dot Product

Use the dot product of the vector with a given vector. This may be useful for measuring deviance from a certain direction.

Other attribute


Name of the attribute to visualize.

See above for the other settings.

Axes Style

X Color

Color of the first vector.

Y Color

Color of the second vector.

Z Color

Color of the third vector.

Show Arrow Tips

Draw a small barb at the end of each axis line.

Houdini 20.0

Getting started

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.

  • Executing tasks with PDG/TOPs

    How to define dependencies and schedule tasks using TOP networks.

  • 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

    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.

  • 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


  • 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.

  • COP2 - Compositing nodes

    Composite nodes create, filter, and manipulate image data.

  • 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

Lighting, rendering, and compositing

  • Solaris

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

  • Rendering

    How to render images and animation from the 3D scene.

  • HQueue

    HQueue is Houdini’s free distributed job scheduling system.

  • Materials

    How to assign materials and create custom materials for shading.

  • Compositing

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


  • 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.

  • Houdini Engine

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

  • hwebserver

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