Digital assets are stored in .otl files. These files must be installed into Houdini in order to be used inside a hip file. There are 3 primary ways to go about installing digital assets.

The most straightforward way to install a digital asset is by manually installing it through the File menu from inside Houdini. By clicking File -> Install Digital Asset Library you can select the asset you want to install into your scene and it will be made available. The advantage of this method is that it is the easiest to use and requires no environment setup at all. The downside is that you must do this for every asset in every file and becomes troublesome very quickly.

You can also place .otl files inside a directory named otls that is located somewhere in the HOUDINI_PATH. When Houdini launches it will automatically pick up any files located in folders named otls in the path and install them into the session. The advantage of this is that you can place many related .otl files for specific scene or a general collection together and have them picked up automatically when you start or load a session. The downside is this method is not sufficient when you want to have more control about where to store assets and limit them to specific shots or sequences.

The last method is to define the HOUDINI_OTLSCAN_PATH that points to any locations you would like to search for .otl files in. The advantage of this is that it allows you the maximum amount of control and flexibility. The downside is that it requires the most work. Once you start with defining this specific search path you now need to ensure that all the default Houdini locations are in this path as well. If this path is defined then Houdini will no longer know to look for .otl files in the HOUDINI_PATH and will not be able to find assets that ship with Houdini.

Houdini can utilize 2 types of scripts: Python (.py) and Hscript (.cmd). These files must be located somewhere that Houdini will search in order to be made available within the session.

Installing Hscript files is the simplist. The .cmd files can be place in the current directory or in a folder named scripts located in the HOUDINI_PATH.

Python is more complex and offers more choices where to place your scripts. The .py files can be placed in a Python specific folder inside the scripts folder (scripts/python) in the HOUDINI_PATH. This is the most generic method and will work with any version of Houdini that supports Python. As of version 11.0, Houdini supports Python 2.5 and 2.6. To specify a script as only being available in a specific version you can place the script in a folder called python2.xlibs located somewhere in the HOUDINI_PATH where x is the minor version number. Currently Houdini does not support Python greater than 2.6. When Houdini searches for python modules it will check the python2.xlibs folder before scripts/python so if you have multiple copies the one in the libs directory will be used. On Linux, .py files can also be placed in the system's Python script path.

Scripts my also be specified by using the HOUDINI_SCRIPT_PATH variable. Like digital assets, Houdini can use a specific path to search for scripts. In the case of the script path, Houdini will be looking in directories for .cmd files, or for folders named python that contain .py files. Using the script path also removes the ability to have Houdini automatically use the correct version of Python libraries based on your version as well. The python libs directories still work with the script path but you must specifically point to one of the directories if you wish to use scripts located in there. Similar to assets, if you are defining the search path you must be sure to include the default Houdini script locations in your custom path. In the case of $HH/python2.xlibs you will have to add the directory for the version you will be using to the path. This can be made easier making use of HOUDINI_PYTHON_VERSION.

Houdini tools are stored in .shelf XML files. These files must be located in a folder called toolbar in a directory that Houdini will search in order for them to be installed and usable in your session. The methods for installing tools are nearly identical to those of digital assets.

The most straightforward method is to place .shelf files inside a directory named toolbar that is located somewhere in the HOUDINI_PATH. When Houdini launches it will automatically pick up any files located in folders named toolbar in the path and install them into the session. Like assets the advantage is the ability to store related tool files in a general location for ease of use.

The tool specific path is the HOUDINI_TOOLBAR_PATH and functions just like the otl and script paths. As with assets and scripts you also must ensure the path is pointing to the default Houdini toolbar locations to get everything that ships with Houdini.

When you install a .shelf tool file it will automatically appear in the Tab menu as intended. However, there is currently no way to add a tool to a shelf. This must be done manually if you want it to appear on a shelf. Certain tools are "intended" to be on the shelf because they may not necessarily have a proper Tab menu entry. To see if a tool should be put on a shelf, and if so which shelf to add it to, you can look at the Help section of the tool. Many tools have a "Using ..." help entry that indicates how to use it and from which shelf the tool is intended to be used from.

To add a tool to the shelf you need to do the following:

1. RMB on the desired shelf and choose Edit Shelf
2. Once the Edit shelf dialog appears select the Tools tab
3. Scroll through the list to find the tool using its label. Click on the tool name to highlight it
4. Hit Accept or Apply to save the changes and the tool will now be on the shelf.

Houdini supports the use of custom icons for digital assets and tools inside the application and help server. The main types of icons that can used include .svg, .png and .jpg. Files of these types can be place in a directory Houdini searches for icons in and will usually be picked up.

The recommended method is to place the icon file in your $HOME/houdiniX.Y/config/Icons folder. This is were Houdini will have the most luck picking up your icons and can persist through different builds. The downside is that the icon will not be displayed inside the help browser when viewing a custom help card that requires the icon.

You can also place the icon file in your $HH/help/icons/*/PREFIX/ folder, where PREFIX is the first all capital letter part of the file name which symbolizes the category of the icon. In the case of icons located on this site, if it has a prefix you will have to remove the prefix before putting it in the folder. The advantage of this method is that the icon will be displayed inside the help browser when viewing a custom help card. The downside is that amount of work required to install it and the fact that you will have to repeat each time you install a new Houdini build and wish to have access to it in that new build.