How do you add effects to 3D model layer?

In HFPro 2017 (for Mac), I found that the only way to add effects to a 3D model layer was to make the layer a "3D plane". But, when rendering the shot, the model disappears from the render about halfway through.

I saw in a previous Hitfilm tutorial video ("How to realistically composite 3D models "), it was easy to add effects to the model layer without Simon changing the type of layer. 

How do I add effects to a 3D model in HFPro 2017?


  • Well--I get to copy/paste something else I wrote today!


    Hitfilm has three "Compositing Modes," 2D, 3D and 3D unrolled. They operate in slightly different ways depending on the media type, and have different applications.

    2D mode for a video or picture layer simply places a 2D image plane on screen. For particles and 3D models, 2D mode immediately renders the model/particle sim to a 2D layer and passes that layer on to the effects chain. However, in 2D mode, the layers are composited in layer order--a ship layer above a particle layer always renders the ship on top, even if the ship is supposed to be passing through or behind particles.

    3D mode converts whatever it's on to a 3D plane--for photos and videos this allows placement in 3D space and also activates basic materials options  so these planes can react to lights and shadows. 3D mode is pretty useless for models and particles--it renders the model/sim to a 2D plane, then moves that flat 2D plane in 3D space. Now, in Hitfilm 3 and 4 this could be used to get proper occlusion while still keeping effects on a layer, but you had to play some tricks--in Hitfilm 3 this was manually animating the plane to always face the camera, and in Hitfilm 4 plus re-rigging a camera to float around the model/particle sim without it's distance changing... Just a pain!

    3D Unrolled is pretty powerful--let's say you've created a Composite Shot with several 3D planes on it and want to embed this in another comp. Embedding this Composite and making it 3D unrolled keeps the individual placement of the 3D elements in 3D space. One of the several "Heads Up" tutorials on the Hitfilm Youtube channel discusses this in more detail. When using 3D unrolled mode with an embedded comp, you can still place effects on the embedded comp layer.

    But, for 3D models and particle sims, activating 3D unrolled also meant you lost the ability to place effects directly on a model/sim's layer--because in 3D unrolled mode the models and particles are calculated, but are not rendered to screen until either a 2D layer is encountered or the top of the layer stack is reached. This means that one can't put effects on a 3D unrolled model/particle layer because effects happen AFTER the layer is rendered, and, by the time the Unrolled layers are summed together for render Hitfilm is past those layers effects chains.

    There's a workaround for Hitfilm 3 and 4 Pro--duplicate the 3D model and alter it's material settings to be all black or all white. Duplicate the composite shot with the model/particle animation and replace the original models with the all black/white version and put everything in 3D unrolled. For particles, you'd adjust everything to be all black or all white. For example, let's use an all white spaceship and all black particle asteroids! An all white ship and all black particle asteroids gives me a white "mask" of the ship that has black cutouts from the asteroids. Then I can bring this comp into the main comp in 2D mode and use it as a set matte source for a 2D ship layer! Basically using a 3D unrolled subcomp to create a travelling matte. This has it's own disadvantages--changing camera or model animation or particle settings desynchs the matte comp from the main comp (so you have to copy updated animation data over), but it was a great way to take advantage of 3D unrolled while still using 2D layers.

    So that's how 3D unrolled has worked since Hitfilm 3 Pro.

    Hitfilm Pro 2017 has the new Depth Layer feature, which lets a 2D model/particle sim layer look at one one 2D model/particle sim layer as a mask. This lets you still add effects to the 2D layer without pissing around with a matte composite. It's got it's limitations--since Layer A can only use layer B as a depth matte, layer C might not occlude properly, unless layer C is using layer A as it's depth mask... so you have to think about how to chain the pointers--but it's still easier than a matte composite."

  • Well, I changed the model layer back to 2D, and applied effects. So, I'm guessing that 3D models themselves don't have to have their layers changed to 3D plane or 3D unrolled. Is that accurate to assume?

  • Correct. Short version. 2D compositing of 3D model lets you add effects. 3D Unrolled model occludes other 3D planes/3D Unrolled models/particle sims, but you can't add effects. 3D plane for a model is pretty silly to do. 

  • Thanks, Triem23. :)

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