Grading, 3D and mixed up z-depth

Hi,

I am having a problem with grade layers changing the z-depth of particles and text.

I have 2 layers:

  • 1. Text
  • 2. Particle Simulator

Both are 3D, and the text is behind the particles in 3D space, using a default camera. Now I add a grade layer to blur my particles

  • 1. Text
  • 2. Grade Layer
  • 3. Particle Simulator

As soon as I add the grade layer, the text appears in front of the particles. This happens whether the grade layer is 2D or 3D.

What am I doing wrong?

 

Comments

  • Grade layers are 2D, and so they break up the 3D space. Try adding a Blur effect directly to the Particle Simulator? Unless you've set it to 3D Unrolled, this should work.

  • It's easy: The grade layer separates the 3D layers. When a grade layer is rendered, everything below is rendered. So layer 3 is now rendered due to the grade layer and appears as 2D layer which is behind layer 1.

    Every 2D layer is separating layers above and below. The engine renders 3D space as soon as it hits a 2D layer. A grade layer bakes everything below together, it's treated as a 2D layer in this case.  So you are working with two 3D areas - I hope you can understand it, English is not my mother language.

  • Thanks Javert, Juda, I just learned something new, and it has prompted another question.

     The first thing I learned - how 2D layers bake the layers

    The second thing I learned - 3D has the effects node, but 3D unrolled does not.

    I already answered my next question by researching the difference between 3D and 3D unrolled. Now I need to familiarise myself when it is best to use each one, and their limitations.

  • Triem23Triem23 Moderator

    3D should be used on plane, photo and video layers. 

    3D Unrolled is used for particle systems, 3D models and embedded Composite Shots that contain 3D layers. Directly using 3D mode on a 3D model or particle sim will probably yield undesired results. 

    It gets a little trickier because filters like 3D Extrusion fake 3D by drawing the extruded image to a 2D layer... Using a 3D compositing mode on a 3D extruded layer can yield undesired results. 

    Ok, (Grade Layers aside) picture a 2D layer like a flat sheet of paper always aligned to the camera. So, 3D extruded layers, models and particle sims are "drawn" on this flat sheet. 3D mode is like moving that flat paper in 3D space. For models, sims and Extrusion this means the drawn image ends at the edge of the paper.

    Now, effects are added after a layer is "drawn." A 2D model/particle layer can have effects.

    With 3D Unrolled the layers are calculated, but not drawn until a 2D photo/video/grade layer is encountered or the top of the layer stack. This allows (say) a particle cloud to truly wrap around a model, but you can't add effects directly to a layer. 

    In Pro 2017 and up there is a feature called "Depth Layer" that can be set in a Layer's Properties. Let's say I have that particle cloud around a model but want glow on the particles. Setting the Depth Layer for particles to the model and vice versa lets these layers stay 2D with correct occlusion AND being able to add effects.

    To add one more complication, lights are effected by layer order for 3D layers/models/particles. Basically don't stick a grade layer between a model and it's light or the grade layer separates the model and light. 

  • "In Pro 2017 and up there is a feature called "Depth Layer" that can be set in a Layer's Properties. Let's say I have that particle cloud around a model but want glow on the particles. Setting the Depth Layer for particles to the model and vice versa lets these layers stay 2D with correct occlusion AND being able to add effects."

    Thanks for the explanation. This part is currently hurting my sense of reality, but I'll give it a shot!

     

  • Triem23Triem23 Moderator

    @Batvink you're not alone. There also aren't any tutorials for that feature to date. I'd done a super fast 2-minute breakdown at one point, but my idiot self seems to have deleted it from the YouTube Channel. 

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