Match move camera line up between Embergen, Blender and Fusion

Typed a long explanatory email for the above images but when I attached the jpgs my email vanished. Here it is:

Hi All

I’ve been diving into Embergen over the hols and am very impressed both with the sensible UI design and the speed and flexibility of the software - great work!

I am running tests to do some smoke and explosion vfx work on a feature. I’m building on Nick’s large scale explosion presets and his brilliant recent smoke and explosions marathon tutorial I’m getting very promising results. I’ve managed to get decent renders out of vdb files from embergen into Blender and render in cycles (noise is an issue but with sufficient tweaking it can be managed) as well as out of the Embergen renderer itself.

So now I’m nailing down the camera and object transfer pipeline between Embergen, Fusion and Blender, which has raised a couple of questions.

I’ve created a 20x20 test grid with the blender Suzanne monkey head in it for scale. The fbx of this transfers between Blender and Fusion perfectly (allowing for the 100th scale difference) and the animation created in Blender plays back as an exact match in Fusion, so I know the file is good.

When I bring it into embergen, however, there is a slight mismatch with the embergen default checkerboard floor. It looks like the floor is slightly below the origin level - see attached closeup. Is there something unusual about the checkerboard that might cause this? If you look at it from the top it lines up exactly so it’s definitely a position issue and as I say I think the fbx is exactly on 0.

Also, when I play back there’s an odd effect in the preview and render windows - it looks like the embergen motion is randomly matching the rendered sequence then not matching by a small amount. This seems to be some sort of playback issue in that the display seems to be showing a position between the frame numbers, even though the UI is showing whole frame numbers (as opposed to numbers with decimal point values indicating it’s displaying a position between the frame numbers).

I checked this by rendering the whole sequence out of embergen and mixing it together with the original backplate sequence - they match up perfectly. The display seems to depend on where it lands when you stop the playback - if it’s on a complete frame you see a match and if it’s between frames it mismatches. This is disconcerting when playing back on the run as it seems to vary between being in sync and out of sync pretty much randomly.

There may be some sort of display setting that will deal with this but I’ve had a good look and couldn’t find anything. I’ve tried running at the native frame rate of 24 fps (set in all three places - import node, simulation node and backplate) and also with all set to 60 fps but the behaviour doesn’t change.

Of course it’s useable given that the actual renders match up but having to render out a lineup test every time you change something is a bit of a drag.

I’ve prepared a little zip file with the ember file, the backplagte pngs and the grid lineup fbx and also a couple of stills showing the issues, but as this is my first post I’m not sure how to upload them. If I get an option to upload when i submit this (“create topic” I assume?) I’ll do so. If not let me know where I can send them. They shouldn’t be very large so I can email or dropbox them if you think they might be useful.

And happy Hogmanay to you all!

PS I can’t upload the fbx, ember or backplate images I find but if you give an email address I can dropbox them. The backplate pngs are a bit bigger than I expected, about 180megs.

PPS and I have also looked at Daniele’s flaming torch tutorial - very useful indeed but he doesn’t seem to have hit the issues I detail above.

Thank you,
Could you send your files to so I can have a look?
So your problems are mismatching animation in the viewport and a mismatching checkerboard plane, right?

Kind regards,

Hi Daniel

Many thanks for the reply.

The mismatch is a display thing - when rendered it matches fine. Embergen appears to be displaying positions between the frame numbers so when the matching bgd plate shows say frame 110 for example the display render might be showing the position for frame 110.5. I thought I’d explained this as clearly as I could in my mail - please see the example screen grabs I posted. It’s not really a problem, more an inconvenience when viewing moving shots. I wanted to know if there was a display setting that would correct this.

And the checkerboard would appear to be positioned slightly lower than I would have expected. I would have thought it would sit with its center at 0,0,0 but it looks slightly lower. This isn’t a problem, just something I wanted to confirm. It’s relatively minor.

I have sent you a download link to a zip file with the fbx, lineup pngs and embergen files.


Hi Paul,
I checked your files.
I can confirm our ground plane seems to be a bit off indeed.
This can be aligned using the Position Offset parameter in the Global Transform tab of the Import node, with 0.04 in the Z-axis in this case. Or use this value in the Ground distance parameter of the Ground node.
Also, the glitchy aligning when displaying can be reproduced.
I’m afraid you didn’t overlook anything and we don’t have a solution to this currently.
I’ll make sure this is picked up by development.
Many thanks for the useful test scene!

Kind regards,

Great, thanks for the confirmation - 0.04 in the Z was what I got as well, just wanted to make sure it wasn’t some misalignment in the fbx set up as I’m doing some stuff that requires accuracy.

For anyone else’s benefit the workflow I’ve settled on is to output vdb files from Embergen after setting up the sim using the default camera, bring them into blender 3.0 to work out the camera move, bake the camera move (and any other moves) in blender - important step!, then render the volume either in Blender cycles (slow) or export the fbx camera from Blender to Emgergen, then render the volume in Embergen (fast) as appropriate, and finally bring it all into Blackmagic fusion for comping. This has the merit of also being able to import the fbx into Fusion so you can use the 3D system in Fusion to render further elements with the same camera move inline to the comp.

Positioning using the global offsets is pretty tricky with only one viewport - are there any plans to add another so you could see the camera view at the same time as the default view?