Import Fbx animation in Houdini Apprentice

There's A Node For That
Feb 1, 2021
3 min read

For a .fbx file to work properly while importing, it needs to be exported properly first from any said software.

In this article, we will see how to properly export .fbx from Maya and import in Houdini.

Open your Maya scene that needs to be converted to fbx.

Make sure you are in the Animation Tab. Select the geometry in your viewport that you want to export and go to Cache > Geometry Cache > Click the option box (tiny square) of Create Geometry Cache

In the window, the only thing you have to change is Store points as: to Double.

By default, it is set to Float.

Geometry Caches store the geometry's vertices' "location" only and no data about the actual geometry's position is stored. Vertex location here means the (x,y,z) coordinates. And the reason why we changed it from Float to Double is that double is just more accurate.

If you want to have in-depth knowledge about this, read here

Give the Cache name and directory and your desired time range and hit Create. Wait for the Cache to finish.

After the cache is done: (attention needed here)

Select the geometry in the viewport which you've just made a cache of.

Duplicate the selected geometry and delete the original geometry.

Let me make it simpler:

When you duplicate the geometry, there will, now, be two of your geometry.

Now, the original one is the one with keys and animation on it.

The duplicated geometry won't have any keys, any animation, or even any edit history on it. And that is the main reason why we duplicated it. Because, when we duplicate the geometry, we get a clean geometry without any edit history on it.

This is a good practice while exporting animations and it won't create any problems when you use it in other software.

After deleting the original geometry, select the duplicated geometry in the viewport and import the cache you made earlier onto this. Go to Cache, (Still in the Animation Tab) Geometry Cache > Import Cache.

Check the animation by playing it. If it doesn't play, repeat the process and be meticulous this time.

Now your animation is ready to be exported. Select your geo in the viewport, Go to File > Export Selection. In the Export Selection option under General options, the File Type needs to be: FBX export. The rest of the settings are default.

If you still want to make sure the settings are at default hit edit in the same window and click reset. Don't forget to change the file type after that. Hit Export Selection.

A new window pops up with the file directory on one side and options on the other side.

Now, more attention needed here :

You'll have to change the settings in 3 places-

1. Under the options, general options find the Geometry tab and uncheck smoothing Groups

2. Below the Geometry tab you will find the Animation tab check the Animation box

3. Scroll down and find the Geometry Cache File(s) tab and check the box Geometry Cache File(s).

You will find a tab named "Set" Click on the tiny down arrow and select "History SwitchSet"

If you have several of them just select the first one

This last step will make sure that your Geometry Cache that contains the animation gets exported. History Switchset is nothing but the Cache. To know more about it. Check out the Autodesk Documentation

So, now all the formalities are done, you just need to give a file name for your fbx and choose a place to save and hit that Export Selection button, and Viola! You can see the timeline running and you will find something like this on the Status bar

Result: directory/folder/filename.fbx

Let's Jump to Houdini: Importing fbx in Houdini

Pretty straight forward here.

Go to File > Import > Filmbox FBX

In the FBX Import options:

1. Click that tiny File button with an arrow and select the .fbx file that you exported

2. Under Filter Options make sure only Geometry, Animation is checked.

Rest should be unchecked. You are only exporting the Geo with Animation. No Cameras, Lights, Materials, even Joints, and Skinning (yes because we have our cache data now)

3. Scroll down to General Options and Check

a. Unlock Geometry File SOPs

b. Unlock Deformation File CHOPs

c. Import directly into /obj network