Rendering animation with camera move and backdrop

Mosk the Scribe

Planning an animation with a camera move - was thinking about using an image in background so it properly captures the camera's moves - but also possible I'd want to use a different background.  

Rendering a png sequence (with background added as Multi-Pass file), if I check 'Render Alpha Chanel' the Background image does NOT show up.

And if I check Use Premultiplied alpha instead, I don't get an Alpha channel, though i do get the background image.

Able to work around this in After Effects with track mattes based on luma values, but is this expected behavior?

Could also render twice with different alpha settings, but thought there'd be a simple way to render the main images and background seperately given that Carrara does support multipass for Background as well as alpha channel.

 

Additionally - in terms of size for background image, looks like I have to set it to tile roughly 6 times so as to get just one full copy in my camera view.  Any tricks to this?  Is the regular camera view's angle giving you about 60 degrees view, hence need to tile 6 times horizontally to make 360 degree circle?  

Thanks

DUDU

Mosk the Scribe said:

Able to work around this in After Effects with track mattes based on luma values, but is this expected behavior?

The track mattes based on luma or chroma values are never a good solutions, the alpha channel is the way to go.

If you don't want to move your background in AE, you can use an HDRI  image for the background in Carrara, another solution is to use a half globe with an image or film as texture.

3DAGE

Hi Mosk

if you're using an image editor to composite,. then you don't need, or want, to render the figures onto a background

render with alpha, then add the background in the editor.

if you're rendering with alpha,. then anything that's not in the scene,. such as a bakground image,. or Sky,,.  will be transparent,.

In the render passes you should have a Background pass

You can use the background image on a layer in after effects,. you'll have much more control over the image position/motion/scale/tone/ or any other effects.

 

in terms of size for background image, looks like I have to set it to tile roughly 6 times so as to get just one full copy in my camera view.  Any tricks to this?

 

In Carrrara,. use the scene "Backdrop" .. which will place the image into your Camera production frame. ....make sure your image/film matches your frame size.

Great for composing 3D objects into video or a background plate.

if you have after effects it's just as easy to add the background there.

 

If the "background" is an HDRI ,. it should be 2/1 EG:( 4000x2000 px) and ideally it should be a seamless spherical image (panorama)

you can make images larger (carrara will handle 16000x8000) if you need a more detailed background. eg 8/4,. or smaller if you only need the light info, and you'll be adding the background in post.

Camera movement in a spherical environment is tricky,. since the image is fixed to a huge sphere,. track and dolly type motions don't work as expected with a physical scene.

 

You can create a Spherical camera in Carrara,. then render out a 360 environment map,.

the camera in carrara can be changed from Wide to Telephoto,. or anything between 6 and 500,. using zoom, and the slider

Hope that makes sense :)

Mosk the Scribe

I do composite inside of After Effects - and am happy to do whatever makes the most sense.

The reason I thought about putting the background inside of Carrara was so that the camera moves would automatically be taken  into account.  

After Effects does have a camera tracker, which I think is supposed to be pretty good, but I haven't used it enough to do it well - and my last effort with it didn't get great results.

If it's a very simple camera movement, not too bad to replicate manually.  But if you're using bezier curves to swoop in on scene/characters, that will be harder.

Were you suggesting/assuming I should use the camera tracker (that's probably something I need to get under my belt, so not opposed to it) - or did you have something else in mind for compositing?

Have dabbled with environment maps - and have Genetica which lets you make them as well, and some Trapcode Effects inside of After Effects can utilize them - so that's another thing I need to learn.  Another few years and I'll be ready to go :)  

But for current project have to focus mostly on getting things done.  Thanks for any sugggestions

DUDU

The last realizes of AE have an excellent and easy to use tracker, there are a few tutos on YT.

The other solution is to buy "Element 3Dv2" from VideoCopilot.