Jump to content
Sign in to follow this  
javin

Invisible floor, but still have shadows

Recommended Posts

I'm sure this has been asked a lot, but I've tried so many different searches and can't find the right thing.

 

I want to composite some Mograph falling balls into some live footage.

I'm going to get a still frame of the footage shot to correctly composite the elements in Cinema 4D by putting the still as a background.

Of course, I will not want a plane to show up in the live footage, but I do want the shadows of the balls to show up.

 

I was planning to export out of Cinema as a mov. with an alpha, and then bring that into After Effects.

 

How should I go about keeping my shadows?

 

Thanks.

Edited by javin

Share this post


Link to post
Share on other sites

Mark the background as Not Seen By Rendered and render out a shadow pass. Composite the shadow pass with the rest of your render in AE.

 

Ahh, I see.

 

Will the shadow pass be a part of the Quicktime mov.? Or does it render as an AE project?

 

Edit: But what about my floor? If I make the floor not seen by rendered, then it won't see the shadows that would have been cast upon it, right?

Edited by javin

Share this post


Link to post
Share on other sites

Ahh, I see.

 

Will the shadow pass be a part of the Quicktime mov.? Or does it render as an AE project?

 

Edit: But what about my floor? If I make the floor not seen by rendered, then it won't see the shadows that would have been cast upon it, right?

 

Put a white plane down as a shadow catcher. Sorry forgot to add that part.

 

When you render, use a multipass render. You then select your different channels: rgb, shadow, specular, etc. Then, when you render, it will output multiple movs (or whatever is your format). This method is really good for controlling your composite because you can adjust different parts of your render.

 

What I usually do in this case is:

 

1. Put an external compositing tag on the objects and mark them for an Object Buffer.

2. In the multipass window, select RGB, Specular, Shadows and whatever Object Buffers you selected. Don't even worry about alpha channels in your RGB pass, you can just use the Object Buffers to cut out the RGB to isolate elements. More control and planning can save you a lot of headache in the end.

3. Save your Multi-Pass Image. I prefer unchecking the multi-layered file box.

4. Render.

Edited by J Montreuil

Share this post


Link to post
Share on other sites

Put a white plane down as a shadow catcher. Sorry forgot to add that part.

 

When you render, use a multipass render. You then select your different channels: rgb, shadow, specular, etc. Then, when you render, it will output multiple movs (or whatever is your format). This method is really good for controlling your composite because you can adjust different parts of your render.

 

What I usually do in this case is:

 

1. Put an external compositing tag on the objects and mark them for an Object Buffer.

2. In the multipass window, select RGB, Specular, Shadows and whatever Object Buffers you selected. Don't even worry about alpha channels in your RGB pass, you can just use the Object Buffers to cut out the RGB to isolate elements. More control and planning can save you a lot of headache in the end.

3. Save your Multi-Pass Image. I prefer unchecking the multi-layered file box.

4. Render.

 

Dude, you're great!

 

Last question: When you say "white plane", do you mean just a regular plain plane? And do I still make it to not been seen by renderer?

Or will the plane / shadows be in separate .movs?

 

P.S I also have Global Illumination set to sky in my project. How will this come into play with all these multi-passes? Will this be able to work exporting as a mov?

Edited by javin

Share this post


Link to post
Share on other sites

Dude, you're great!

 

Last question: When you say "white plane", do you mean just a regular plain plane? And do I still make it to not been seen by renderer?

Or will the plane / shadows be in separate .movs?

 

P.S I also have Global Illumination set to sky in my project. How will this come into play with all these multi-passes? Will this be able to work exporting as a mov?

 

When I say white plane I do mean a plain plane. :P

 

Render it out with the rest of the objects in your scene and use the object buffer to cut it out of your RGB pass. Then, you will have your RGB with just your objects and a seperate shadow pass that will include the "floor" with the shadows on it. You can use the objects in different ways to cut out shadows and what not. For example: use the OB from the objects in your scene as a Inverse Track Matte on your shadow pass. This will leave you with just the shadows on the floor instead of double shadows on your objects (shadow pass + render pass).

 

Or (sorry, I just keep going here)

 

Render out diffuse, specular, reflection, shadow passes and then comp those together. There is a couple different ways of doing this.

 

I don't think the GI will matter.

 

You can export any format you want. I suggest using Object buffers so you don't have to Quicktimes with alpha channels. (I hate alpha channels)

Share this post


Link to post
Share on other sites

Good luck. Let me/us know if you need anything else.

 

 

 

Still extremely confused. I'm trying to render out two things. One, just a video of the balls, no shadows. And then, just a video of the shadows.

 

Here are some pics and explanations:

 

picture1culh.png

Here is my scene. For the render of just the balls I will have all the objects except the balls turned to not visible in render, or not visible by camera.

The floor has an object buffer on it.

 

picture2scq.png

 

I have a feeling I am making this so over-complicated. For a thing that really should be super easy.

Edited by javin

Share this post


Link to post
Share on other sites

It would be much easier if you submit the scene file,

 

what you can try, on your render page, Regular Image checked and save...do one more render where Regular Image is unchecked, and multipass is active(this should be tga)

 

you should get 2QT`s, one for alpha and one for shadow, (assuming that the setup on your scene is ok)

Share this post


Link to post
Share on other sites

It would be much easier if you submit the scene file,

 

what you can try, on your render page, Regular Image checked and save...do one more render where Regular Image is unchecked, and multipass is active(this should be tga)

 

you should get 2QT`s, one for alpha and one for shadow, (assuming that the setup on your scene is ok)

 

This is exactly what I tried, but the shadow video is just white.

Here is my scene file. (1.4mb zipped file) Someone please take a look at it.

 

http://javinladish.c...edballz.c4d.zip

 

 

Edit: Also, am I supposed to mess with the luma mats in After Effects for the "Shadows" Comp? The shadow images seem all white, but I was just watching Nick's tutorial on camera mapping and what not, and he does stuff with the luma mats in AE. This would possibly turn the shadows to be visible? Maybe? Rawr?!

Edited by javin

Share this post


Link to post
Share on other sites

so you want something like this? ( of course you dont have shadows if you dont have lights to cast them, or AO enabled)

 

14241431.jpg

 

add a bg , load your image on the luminance channel,

on your floor add the same material, only load this on the color channel

select your floor material and tell him you want camera mapping projection drag your camera and hit calculate

on the same material you can enable AO

on your GI, change it to IR+QMC animation

Add AO from render menu, and increase the contrast to 60/80

Edited by stoiqa

Share this post


Link to post
Share on other sites

Stoiga, I will be using an HDRI image on my sky, and my GI will already be set to that.

I don't want to render out my background at all; it will just be a still frame from the live video that I will be using for compositing my 3D elements.

 

But on a lighter note, I found two good tutorials on the subject and should be fine after I actually shoot the footage!<br><br><br>Edit: Got it to work, sorta.<br><br>I guess making any shadow catcher doesn't like working with GI.  So I just ditched the GI.<br>

Edited by javin

Share this post


Link to post
Share on other sites

To get a shadow pass out of a GI render , with no lights,

you use the Diffuse pass.

Have your floor and background white and with a CompositingTag,

"Compositing Background" checked.

 

I personally don't recommend Object Buffers as you don't get

a proper Straight Alpha.

Do a separate render of your objects check "Straight Alpha".

(Hide the floor and background planes for this)

 

Cheers

Lennart

Edited by tcastudios

Share this post


Link to post
Share on other sites

To get a shadow pass out of a GI render , with no lights,

you use the Diffuse pass.

Have your floor and background white and with a CompositingTag,

"Compositing Background" checked.

 

I personally don't recommend Object Buffers as you don't get

a proper Straight Alpha.

Do a separate render of your objects check "Straight Alpha".

(Hide the floor and background planes for this)

 

Cheers

Lennart

 

Thanks. I'll give this a try. Even if I can't get this to work, I'll be fine doing the other method that works with the set up lights.

 

This forum is full of geniuses!

Share this post


Link to post
Share on other sites

After messing about a lot last year I also use the 2 render method. Multi-pass but use one render for your objects with compositing tags on your floor and BG then a quick second render (you can switch most settings off to run it super quick) with compositing tags on everything except the floor so you just get a clean shadow pass. Good luck

Share this post


Link to post
Share on other sites

After messing about a lot last year I also use the 2 render method. Multi-pass but use one render for your objects with compositing tags on your floor and BG then a quick second render (you can switch most settings off to run it super quick) with compositing tags on everything except the floor so you just get a clean shadow pass. Good luck

 

What format do you usually render in?

I'm such a big fan of .movs, but it seems that a lot of people on here aren't.

Share this post


Link to post
Share on other sites

i think most render out to tiff or exr image sequences...easy to stop/start a render from a certain frame....don't lose alot of work in an outage...easy to rerender a select set of frames.

I think .movs are great for tests and quick comps...but thats it

Share this post


Link to post
Share on other sites

What format do you usually render in?

I'm such a big fan of .movs, but it seems that a lot of people on here aren't.

 

Yeah you gotta get into image sequences. Think there's a thread talking about it in the last week or so. I generally use .psd sequences 16 or 32 bit, sometimes exr or hdr

Share this post


Link to post
Share on other sites

I'd like to bump this because I seriously could not get this to work. What I did so far is create a plane set it to composition in background. Enabled multi pass for shadow. I want to keep the shadows but the floor isn't being removed for the main render. I might also be doing things wrong in after effects. could someone help me layout the basic layers and this whole inverse luma matte thing?

 

My project file : http://www.sendspace.com/file/2u59tz

Share this post


Link to post
Share on other sites

I'd like to bump this because I seriously could not get this to work. What I did so far is create a plane set it to composition in background. Enabled multi pass for shadow. I want to keep the shadows but the floor isn't being removed for the main render. I might also be doing things wrong in after effects. could someone help me layout the basic layers and this whole inverse luma matte thing?

 

My project file : http://www.sendspace.com/file/2u59tz

 

Go into Render Settings. Under Save, expand Multi-Pass image, check Save box and after that, you can specify which format you want. Without this option activated, Cinema 4D will not render out your Multi-Passes.

 

Good luck.

Share this post


Link to post
Share on other sites

@vozz That one suggest to render with background, which I don't want because I want to decrease render time. I'm sorta basically asking the same thing the original thread owner made, but none of what has been posted worked/made sense.

Share this post


Link to post
Share on other sites

really? That's good to know, guess I'll have to make my own tutorial on this =P

 

can't really help you at the moment, as I really do not know your problem.

 

Can you tell me what you tried and what problems you had with each method?

 

I can't be bothered reading the whole thread.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

×
×
  • Create New...