Shape3D not blocking light from spotlight

Hi all

I'm floundering around in Fusion trying to set up a 3D environment, with the objective of getting realistic-ish looking lighting and shadows cast behind footage of three actors.

I am working in Resolve Studio 16.2.2.012 on macOS 10.14.6.

I have things half working. I have a Camera3D, three ImagePlanes (actors, wall, floor), a Spotlight, multiple Merge3D nodes, and a Renderer. I have achieved the basic task of having a spotlight cast light onto my scene, which projects shadows onto the back wall and floor. I can adjust this light by moving the spotlight and altering its intensity/cone/penumbra/etc. When the spotlight is off, the scene is 100% black.

The problem I have now is that ideally I'd like it to appear as if the light is coming through a grate / bars. The actors are meant to be in a 17th century prison cell / dungeon, underground, with the only light coming from a grate up high in the wall.

I thought this would be quite easy: I'd make some 3D cylinder shapes, and put them between the spotlight and the scene.

But no matter what I do, I can't get a 3D cylinder to block the light! That is, unless I make one stupidly big, and even then it doesn't always block anything.

Here's how my scene looks in the Perspective 3D viewer:


You can see I'm testing with a huge 3D Cylinder - big enough to impress the monkeys on 2001 A Space Odyssey - and it's between the spotlight and the scene. Here's another view, from the perspective of the spotlight, that confirms this:


No matter how I resize or move this cylinder, the light in the scene doesn't change at all. Except on a few occasions, when I've made the the cylinder enormous, I have managed to get it to suddenly block all or most of the light. But I can't work out how to replicate this, and make it actually useful - ie blocking just a bit of light, and casting a suitable shadow, with a small cylinder.

Here are the settings for the cylinder and spotlight:


I'm obviously doing something wrong or misunderstanding something basic, so I'd be most grateful if anyone could point me in the right direction.

It's hard to tell from your screenshot, but it looks as though you might not have Shadows turned on in the viewer.

Unfortunately, I find the icons for Lights and Lights + Shadows almost indistinguishable without putting my nose on my monitor.

I would suggest moving your spotlight back from the scene more and if you still want to see the circle of the light, reduce your cone angle. In the top screenshot below, I had the spotlight further away then in the bottom screenshot, not by much but enough to affect the shadows.

Multiple Merge3D you say? Careful, unless you set .PassThroughLights to be 1, they won't pass through lights. And even then, lights only associate downstream, not upstream.

It's important (not just helpful) to remember that each 3D tool can represent a valid scene graph. It's not just the final tool that collects the scene. Make sure your lights are included with the geometry they are meant to collect/affect.

Thanks very much for all the replies!

Chad: Thanks for the tip. I did have Pass Through Lights enabled, but I've now simplified to using just a single Merge3D node for now.

Bryan: Indeed I didn't have shadows enabled in the 3D viewer, and that does help to see what's going on - thanks for that, I'd not even noticed that was an option. Previously I was only looking for shadows through the Renderer or Main Out node.

xunile: Thanks, this seemed to do the trick. Greatly increasing the distance between spotlight and 3D shapes enabled me to get the shapes to cast a shadow.

I still don't quite understand this - if I can clearly see the shapes in the view from the spotlight (which I confirmed by choosing Camera -> Other -> Spotlight, I don't get why it wouldn't cast a clear shadow. But then I barely know what I'm doing in 3D!

Thanks again, all.

OK I'm confused again

As soon as I managed to get some shadows from my cylinders, I realised I could no longer see the shadows I had previously had cast by my actor video, which is on an ImagePlane.

I'm now in a position where I can clearly see shadows cast by my actor ImagePlane in the 3D Viewer - however, it doesn't correctly use the alpha channel, so it just shows up as a huge black square. That may be fine, perhaps just a limitation of the 3D Viewer. (EDIT: I just noticed that there's a separate Transparency setting in the 3D Viewer, which appears to be mutually exclusive with shadows, so I guess that's fine? 3DViewer can either show alpha, or shadows, but not both at once?)

Regardless of the 3DViewer, in the main Renderer node I can see no shadows cast at all by my actor ImagePlane.

I had this working hours ago! And I don't know what's changed.

Here's my nodes (click for larger):


Here's the 3D Viewer (looking at my single Merge3D node, to which everything 3D is connected), with all 3D options enabled (lighting, shadows, etc) - the actor ImagePlane at the front is clearly casting a big black shadow on the wall behind, which doesn't take into account the alpha channel:


And here's my second viewer, looking at the Renderer3D node. It shows the ImagePlanes, it shows the spotlight, but there is not a shadow to be seen. This is the same regardless of where I position the spotlight - left, right, up, down, near, far, right off to the side at an oblique angle, etc:


(The lighting currently shown is just a random position and setting, trying to get some shadows. Note ignore the small shadow behind the male actor's head, that's come with the green screen key and I will try to remove it later when I do the final key.)

I noticed that if I changed the Renderer to OpenGL renderer, then the shadow square immediately appeared, looking like it does in the 3DViewer, ie one huge black square of shadow. The alpha channel is not used. In fact I haven't ever managed to get the OpenGL renderer to use the alpha channel for my actor ImagePlane, so I've not been able to use it at all (shame, it seems to be faster than Software).

In Software renderer, I've definitely seen shadows before, both from 3D objects, and cast by my actor ImagePlane. But at least for the actor plane they're gone now and I can't get them back.

Renderer is set to Enable Lighting and Shadows. Shadows are enabled in Spotlight, all ImagePlanes (caster, receiver, and 'affected by lights'). I've even tried quitting and re-opening Resolve, because that's definitely solved weird problems for me in the past

Thanks in advance for any more advice.

I realised the 3D Viewer screenshot I showed above might not be the best example, as the spotlight was flat-on to the image planes. I think there probably should still be some shadow visible, but it wouldn't have been super obvious perhaps.

Here's a better example where the camera is far off to one side, and the 'big block' shadow is clearly slanted. This should surely cause a visible shadow to cast across the Renderer from left to right. But as before, no shadows are visible in the Renderer.

3DViewer:


Renderer - lighting, ImagePlanes, no shadows:

I'm not sure where you are going wrong now. In the images below, I have a clip with a TV with a greenscreen center keyed out. I connected it to an ImagePlane3D node and added a cylinder and a shape3D plane as a background. I added a camera and a Spotlight. Finally, I added a Renderer3D node and set it to Software Renderer with Lighting and Shadows enabled. I am able to see both the shadow of the cylinder and the ImagePlane with the light shining through the center of the TV which was keyed out.

What happens if you put the spotlight right above and behind the camera?

Thanks very much for the reply again.

I found the problem - it was a stupid issue and user error, of course!

Somewhere along the line of my testing, I think when I was trying to get the cylinders to cast shadows and couldn't work out why they weren't, I changed the actor ImagePlane's Transmittance colour. Its 'attenuation' colour was white, so I guess it was casting white shadows

I finally figured it out by dragging in a new media clip of the actors and connecting it to a new ImagePlane, which suddenly worked. Should have done that a lot sooner.

Thanks again for the responses.