Helmet glass wrapping reflection tricks?

Hi there, I need to create a glass space helmet window.
So far, I’ve got a reasonable spaceship cockpit hdri, a pretty good 2d helmet track and a sphere tracked to it for which to hopefully receive a 360 reflection, which I’ll them mask and comp downstream. It’s the last part I’m having trouble with. How do I get the reflection to appear on the sphere, with the correct warping of the image around the sphere (or at least something I can cheat?) There’s camera movement (so the hdri is tracked to the background) and the helmet does a move down onto the guy’s head so the sphere needs to reflect the tracked cockpit.
Applying a reflection map to the sphere is not really doing anything, seems to be diffusing only? (as in it’s stuck to the model) I tried this with 3d text and that works as expected, so I’m not sure why a sphere isn’t doing the do?

Many thanks in advance :slight_smile:

Does the sphere have actual rotation on it in 3d space? Like if you diffuse wrap a texture on it, that texture looks as though it is moving in 3d space with the helmet? Can you share a screen shot of the reflection map set up?

Unfortunately I can’t - the sphere doesn’t rotate, it’s just a 2d xy track, but I want the cockpit texture to be locked to the bg, so when the sphere moves around, the cockpit hdr should stay put, intead of move with the sphere, as it currently incorrectly does.

Have you tried Stingray Reflections?

Camera track + object track (or even a halfway decent hand-track, since you can do all the 2d nuance downstream) on a sphere with a physically based shader with roughness at 0 and metallic at 1.0.

Hang your HDR off the tracked camera and it’ll warp the reflection appropriately.

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@andy_dill - I’m just curious now as how this would relate to a lock off. I’m no physicist, but I’m thinking about just a mirror ball for instance with a locked off camera (let’s say on this space helmet shot it’s just the astronaut moving- not camera move). Ok, so it’s reflecting 360 degrees of light- so moving the ball/ helmet/whatever up and down for instance, rotating it on any access, you’re not going to really see much difference in what’s being reflected in it. A little bit if it wraps around the edges and distorts, but not a huge difference, that’s where the matting in of the helmet emphasizes the portion of the 360 degrees of reflecting off the spherical surface. I could be thinking about this wrong? I’m just super curious about this now. Like what’s happening at 3:52 in this video Why visual effects artists love this shiny ball - YouTube

I tried Stingray, but I can’t get the surface to be on the inside of the ‘sky’ sphere… Anything I should do differently?

@andy_dill I’ll give that a go… I think I know what you mean. Camera tracking is not really gonna work on this shot and gasp in all my years of Flame I’ve never done an object track…! (always planar, 3d & 2d)

Yeah, I’ve never pulled an object track in Flame. Hahaha. You mentioned camera tracking in your original post so I was thinking that’s already done. Honestly even a hacky ass one could be of some use, depending on the plate’s camera move.

If the camera is locked off, the reflections won’t move a ton as @BrittCiampa mentioned. It’s easy to look at the effect though: just make a new action with no layers and add an IBL. It’ll preload the “stutgart.exr” one. Hang that off the camera, then add a sphere and chrome it up with 0 roughness and 1.0 metalness. Then just move the ball around in space. Also move the camera around the object to see how the reflections change then.

If the camera is untrackable but still parallaxing, I’d just do a smooth approximation of the move. A couple of keyframes where the object’s scale and movement are reasonably close. Then add any hand-animation (aka “object track”) if the hemet is moving in space space separate from the camera.

Then render out the chrome ball, and a copy of the chrome one that is just a diffuse texture with a bunch of dots for tracking. stabilize the dot ball with a 2d track and then 2d track that onto your plate and once it’s sticky, swap it out for the chrome render.

Because you’re using a 2d track to capture all the jittery stuff, any sloppiness with your hand-tracked camera and object are going to be much less noticeable.

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Wait, do you mean cheat the texture move? I could probably paste the bg track information and invert it, that would actually work… Not very elegant though. :slight_smile:

Well, not to take away from this topic- (I think you should do what @andy_dill is suggesting above) But I’m saying that if the camera isn’t moving very much, the reflection will appear relatively statically locked to the sphere because of the nature in which a sphere reflects light. Check out what he’s doing with the mirror ball in this video at 3:52, moving up and down, rotating back and forth, yet the reflection only changes a little in relation to the ball- and a lot in relation to his fingers. Imagine his palm and fingers are the space helmet- the mirror ball is the helmet visor Why visual effects artists love this shiny ball - YouTube

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You said you had an IBL yeah?

If you plug that IBL into an action, add it as an IBL layer and hang it off the camera, it will apply “light” (aka reflections) to all objects in the action scene.

So you’re not cheating the texture since you’re not using the texture at all, just the IBL as a reflection.

but Britt’s got a very good point on how a ball reflects: if the camera isn’t moving around the ball, the ball’s reflection is basically static, even when translating in-frame. So if your camera isn’t Michael Bay’ing around the helmet, you can just track in a still of the reflection on a sphere.

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I used a combination of IBL, spot lights for specific placement of the spec highlights, and IOR on the geometry.

Also play around with having two spheres… one slightly smaller inside the other to create ‘thickness’ of the glass. Use separate Shader nodes for each sphere and make the roughness slightly different.

Let me know if you want more details!

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@GPK I’d be keen to hear your workflow on using a sky dome as a sphere and pulling a reflection from the inside of the sphere instead of the outside?

Thanks for all your thoughts on this one guys, I’ll be back on the tools shortly :heart:

With the two spheres thing you must’ve comped downstream for that?

Unclextacy –

Two things I don’t see mentioned so far…

Perhaps try projecting the reflection texture onto the sphere? You can use either a Projector node or a Diffuse Map set to Projection mapping.

Second, select the sphere geometry and switch its “Shade Both” pop-up to “Shade Front” so the projection source doesn’t get applied to the back of the sphere.

Yes - separate outputs from action and then screen/overlay both passes.