HTB - Houdini to Blender Exporter

BEFORE ANYTHING ELSE!! -> You need a Houdini license to use this product, aprrentice license is not enough.

Also this addon is tested for blender 4.0.2 or higher.

This tool allows you to import in an easy, quick and efficient way attributes from Houdini to Blender Geometry Nodes. Works with regular geometry, point clouds... no volumes tho!

POINT ATTRIBUTES THAT CAN BE EXPORTED: integrer, float, vector, color and quaternions.

Check this quick YT video for a quick walkthrough:

Also here I breakdown a whole project in which I used this addon.

DOCUMENTATION:

1. INSTALLATION
   • Install HDA in Hodini
   • Install HTB add-opn in Blender
2. EXPORT FROM HOUDINI
   • Connect your geometry to the HTB hda.
   • Set export settings
   • If you have attributes that don't change over time (and your point number is constant) consider saving those attributes as one frame (not frame range) and the time dependant attributes as frame range. This will save memory
   • Let it cook!
3. IMPORT TO BLENDER
   • The HTB will have exported a folder with an alembic, an attributes folder and a cache folder (you can forget about this last one)
   • Import the alembic
   • In the N panel you'll see the HTB addon. Click on your imported alembic, set the folder as the attributes folder, click Import Attributes and... that's all. Now you should have your attributes in your spredsheet.
4. WARNING ABOUT EXPORTING VECTORS FROM HOUDINI TO BLENDER:
   • So as you already probably know, the coordinate systems in Houdini and Blender are different. So, when you export a velocity or a normal vector (for example) , a change on its components is neccesary, in particular (x,y,z) -> (x,-z,y).The HTB addon takes care of that, but, if you export a 3 dimensional scale attribute, you might need to tweak the attribute (just make all its components positive).Anyway, 98% of the times you will just export regular vector, so no worries about it.
   • Quaternions will be converted to Euler rotations (with Blender axis orientation)

HOW THIS TOOL WORKS:

I based the workflow in the vertex animation textures that are used for FX in real time graphics (like Unreal). Basically attributes are saved in an EXR image, so each pixel contains the data (attribut values) of a certain (or several) points. Check the breakdown project for a more in depth explanation.

This is how a vector attribute of a 10 million point mesh would look. Being the image resolution around 1000 x 1000 pixels! And for a float attribute even less!! Around 500x500 pixels. Not so much :)

FUTURE IMPROVEMENTS:

• Option for baking attributes in Blender
• Frame offset option

And more!!!!

Please let me know if you like it, if something can be improved..... love feedback :)

Thanks!

Artichoke