Compositing Multiple Render Layers Causing Final Render Alignment Issues

Hello Everyone.

I have a compositing issue (I think) that has me completely stumped. Here is my problem.

Currently I am making a moving animated scene.

I have multiple scenes set up so I can composite volumetric light into a cycles render. Volumetric Light in one layer, the solids in another layer (rendered in cycles) , I then composite the two together.

With the cycles/solid layer selected, I use the nodes to composite the volumetric light layer underneath.

It more or less works as expected. It looks fairly nice.


When the volumetric lighting scene renders, the image seems to have been enlarged. It is as if the camera has been zoomed in ever so slightly. Obviously when I composite the image with the solid layer, they do not line up. All the shadows are out of alignment.

Now I select the blender volumetric lighting layer, and try and render the solids into the scene. Now all the shadows/ objects line up correctly. However, I do get some weird flickering going on as Blender tries to composite the two scenes together.

Most confusingly, sometimes the layers line up, sometimes they do not.

I have had no luck solving the issue. The camera location, rotation and scale are identical in both scenes. As are the objects location, rotation and scale. The Animation keyframes for the objects are also identical.

I have double checked the camera settings, alpha settings, render settings and everything seems normal and identical.

I have also looked at the data blocks and I think they are okay but in honesty I’m not quite sure what I am looking at. Furthermore I have tried using a single camera for all of the scenes but this has not fixed the issue.

I don’t know what it is, maybe the pipeline is out of sync, but I highly doubt it. I think it is more likely to be a bug.

I might try rendering of the layers separately and composite them in a different program.

If anyone has any suggestions I will be truly grateful for your help!

I will try and get a picture up to better illustrate what is happening.

Merry Christmas.

If anyone has any suggestions I will be truly grateful for your help!

I will try and get a picture up to better illustrate what is happening.
Why not include the screenshots and a link to an example blend file with your original post. If you were given just a wall of text would you know exactly how the scene and render settings were constructed. If not, why expect other people to know

Here is an image of the kind of results I am getting.

Agreed. How would I know where to start if you claim to have done everything? A stripped down blend file would be easiest to solve. Also you could send the scenes as strips to the vse and mix them together to check animation alignment.

I did actually post a screenshot yesterday but it appears that the moderator has not approved it. Not my fault. I don’t expect anyone to to know anything.

I’m not putting a link up because I don’t trust the internet.

I will try again.

Here are the results I have been getting.

Here are my render settings.

If any more screenshots are required I will be more than happy to upload them.

And here is a picture of my timeline.

Is this a zoom or dolly shot? It seems that the right hand side is pretty much right but the left gets progressively worse as you go across the image.

I have the camera damp tracking the cannon ball with a set influence. The cannon ball is clamped on a path. The camera follows the cannon ball as it travels across the scene.

I have split the animation into two halves to keep the file size down. This explains why there are keyframes outside of the render frame range.

I did make a bit of progress last night. Unfortunately it also made me think what I am encountering is a bug.

If I am in the UI editor, scrub through the timeline and render a frame off, the layers will not be aligned when the render is complete. However, if I go into 3D view, scrub through the timeline, and then render, everything matches up.

I may just cut my losses and start again. I have a back up file and it won’t take me too long to set up another volumetric lighting layer.