Converting image files

On this page

Overview
How to

Overview ¶

Houdini can handle most image formats, but in general you should use Houdini’s image format (.pic or .rat) or OpenEXR format for textures. Those formats have additional features such as tiled loading that can save time and/or memory.

How to ¶

To... Do this

To...	Do this
Convert an image using MPlay	Choose Render ▸ MPlay ▸ Load disk files and pick the file you want to convert. In Mplay, choose File ▸ Save frame as. Save the image with a filename ending with the file extension of the new format.
Convert an image from the command line	In a Houdini shell, use the iconvert command-line utility to convert images between formats. For example: iconvert butterfly.pic butterfly.rat You can type `iconvert` alone on the command line to see the list of supported formats. The iinfo command will print information about image files.
Convert an image using a compositing network	Choose File ▸ Import ▸ Image and pick the image you want to convert. This will create a new compositing network with a File compositing node that loads the image. If you want to convert the file procedurally (so you can run the conversion as part of a render network), choose Render ▸ Create render node ▸ Other output nodes ▸ Composite and set it to render the output of the compositing network. If you just want to convert the file once, right-click the File compositing node and choose Save image. Save the image with a filename ending with the file extension of the new format.

Convert an image using MPlay

Choose Render ▸ MPlay ▸ Load disk files and pick the file you want to convert.
In Mplay, choose File ▸ Save frame as. Save the image with a filename ending with the file extension of the new format.

Convert an image from the command line

In a Houdini shell, use the iconvert command-line utility to convert images between formats. For example:

iconvert butterfly.pic butterfly.rat

You can type iconvert alone on the command line to see the list of supported formats. The iinfo command will print information about image files.

Convert an image using a compositing network

Choose File ▸ Import ▸ Image and pick the image you want to convert.

This will create a new compositing network with a File compositing node that loads the image.

If you want to convert the file procedurally (so you can run the conversion as part of a render network), choose Render ▸ Create render node ▸ Other output nodes ▸ Composite and set it to render the output of the compositing network.
If you just want to convert the file once, right-click the File compositing node and choose Save image. Save the image with a filename ending with the file extension of the new format.

Mantra materials

Using materials ¶

Using materials

How to assign assign materials and use the library of built-in materials.
Material palette

Lets you assign materials to objects and primitives interactively.
Overriding material parameters and properties

How to change material parameters on individual objects or pieces of geometry.
OpenGL Shaders

How to customize how materials appear in the OpenGL viewport.
Material code caching

You can pre-compile a material as a digital asset to speed up shader compilation at render time.

Textures and UVs ¶

Creating materials ¶

Building materials

The basics of how to create, combine, and modify materials in Houdini.
Layering shaders

How to mix and layer two or more materials together to create a combined material.
Material parameters

How to build a parameter/input interface for your custom material.
Working with VOPs

Tips for working with shaders in the VOP network.

Guru level ¶

Material exports

How to export extra information from the shader and save it as part of the rendered image.
Absorption and nested dielectrics

Automatically scoop out geometry with one shader from inside overlapping geometry with another shader, allowing different shading properties inside.
Material stylesheets

Material stylesheets are a highly technical solution for assigning materials and overriding material parameters on packed geometry.
Loops and conditionals in VOPs

How to create looping and conditional blocks of nodes in VOP networks.
Writing a custom viewport shader in GLSL

Other renderers ¶