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mbw
10-19-2008, 08:07 PM
Hi all,
I was searching the forum for an equivalent to MAX's shadow matte
and didn't see anything realitvely new posted on in. (C4D 10.5). There
is a compositing tag, but that doesn't seem to work the same way at
least by my understanding of the documentation.
What I would like to do is have a floor polygon and some other simple
junk just catch the shadows so I could composite it with the rendered results
in AE.

In 10.5 is there an equivalent feature?

Thanks

MBW

Per-Anders
10-19-2008, 08:30 PM
Use the multipass, shadows can be retrieved per light or as a global shadow pass.

joshfilms
10-19-2008, 09:32 PM
Besides a multipass setup the closest thing I have seen is the shadow catcher plugin. Search around its a free download somewhere.

mbw
10-20-2008, 03:06 AM
Use the multipass, shadows can be retrieved per light or as a global shadow pass.


How do I setup the scene to have an object capture the shadows but not be
present in the output movie. As far as I can tell the multi-pass will output a
file that has shadows only if this object is in the rendered RGBA output.
I'm trying to figure out how to composite a C4D object into a scene, but can't
seem to figure out the workflow.

For example:
video of a street and I want to make a ball bounce across it. I've tried a background
but there must be some floor to catch the shadows. Whenever I put a floor in then
project the background on to it, the floor is in the rendered output.

I know I am missing something simple just can't seem to get my brain around it.
The compositing tag documentation just doesn't have any examples in it so there
is probably a setup issue.


Any help would be appreciated.

Thanks

MBW

Per-Anders
10-20-2008, 04:05 AM
Again use the multipass and use the illumination/diffuse/specular passes (or a combined pass with a "Blend" channel), the shadows are just that, shadows, not surface shading so just set to multiply.

An easy way to get to grips with the various layers is to just choose the add all image layers option, then you can see what you have available to you after you render in Photoshop/After Effects/Motion or whatever it is you want to use to composite your passes together with.

You can also make a shadowcatcher for a specific surface by using the Sketch & Toon materials or the core "Lumas" shader (or just using a compositing tag), don't forget to use object mattes via object buffers as otherwise you'll have to cut things out by hand if you go this route.

johankraus
10-20-2008, 08:06 AM
try to use compositing tag with compositing background option checked http://www.youtube.com/watch?v=UYDj3Fq_Mo8

okazaky
10-20-2008, 01:19 PM
Unfortunately there is nothing similar to the "Matte/Shadow" from 3dsmax in C4D.
The only way to render shadows with alphachannels is the shadowcatcher-plugin (or with special workarounds with the lumas or sketch and toon shader)

C4D isn't really up to date regarding this feature and I hope Maxon will include it in the next version.

Best regards,
Daniel

mbw
10-20-2008, 06:56 PM
Again use the multipass and use the illumination/diffuse/specular passes (or a combined pass with a "Blend" channel), the shadows are just that, shadows, not surface shading so just set to multiply.

An easy way to get to grips with the various layers is to just choose the add all image layers option, then you can see what you have available to you after you render in Photoshop/After Effects/Motion or whatever it is you want to use to composite your passes together with.

You can also make a shadowcatcher for a specific surface by using the Sketch & Toon materials or the core "Lumas" shader (or just using a compositing tag), don't forget to use object mattes via object buffers as otherwise you'll have to cut things out by hand if you go this route.

I see... If I use the compositing TAG I'm going to have render out an objectbuffer matte
to cut the object from the background. This seems like creating more work that should
be necessary. I would think that for Visual effects it would be much nice to render out
the objects without any objects with compositing TAGs but still capture the shadows.
From what I understand this is a two step process. One with the objects to capture
the shadows and one to capture just the rendered object.

Maybe I am making it too complicated so I'll try your idea of rendering out all and
see what is available.

MBW

mbw
10-20-2008, 06:59 PM
try to use compositing tag with compositing background option checked http://www.youtube.com/watch?v=UYDj3Fq_Mo8

This is a very useful video. In fact it answered some of my questions. (getting rid of
the SKY object and use of the compositing TAG) but the issue I have is that the
rendered out still has the backround and plane with compositing tag in it.

If I want to compositing my rendered object, it seems that I am going to have to
render out the object buffer as well to cut the object out by itself.

MBW

mbw
10-20-2008, 07:00 PM
Unfortunately there is nothing similar to the "Matte/Shadow" from 3dsmax in C4D.
The only way to render shadows with alphachannels is the shadowcatcher-plugin (or with special workarounds with the lumas or sketch and toon shader)

C4D isn't really up to date regarding this feature and I hope Maxon will include it in the next version.

Best regards,
Daniel

Daniel,
I agree just based on the simple WEB tutorials I've seen of both methods. However,
I will admit I don't know either real well so there are probably things that can be
done differently by myself. Hopefully MAXON will add a shadow matte capability to
make this easier.

MBW

Per-Anders
10-20-2008, 07:10 PM
A masked shadow is not all that useful for compositing, it just sounds like a good idea till you think it through in terms of real usage and workflow (then you realize it's a bit of a 80's/90's legacy hack). Just use the shadow output from multipass together with an object matte (compositing tag on objects you want to have their masks from setting the Object ID then in multipass you add the pass to render the corresponding Object Buffer), it's far more useful and controllable, and if you really want you can use it as a matting mask for something else, including the original rendered RGBA image.

mbw
10-20-2008, 07:43 PM
A masked shadow is not all that useful for compositing, it just sounds like a good idea till you think it through in terms of real usage and workflow (then you realize it's a bit of a 80's/90's legacy hack). Just use the shadow output from multipass together with an object matte (compositing tag on objects you want to have their masks from setting the Object ID then in multipass you add the pass to render the corresponding Object Buffer), it's far more useful and controllable, and if you really want you can use it as a matting mask for something else, including the original rendered RGBA image.

I'm definitely not saying things correctly. Sorry about that, but there are two issues:
1) getting a shadow
2) Getting a rendered sequence of just the object with all the correct lighting, reflections
and such.

For 1: it seems that you need some geomtery that you can put the compositing tag
on, set as composite_background. The use multipass to render out the shadow sequence.

For 2: Because the background and floor(used in shadow capture) need to be visable
for the correct lighting and reflections they appear in the rendered output. So the
solution is to render out a RGBA sequence along with the object matte and cut the
object out in your compositing program.

It seems that both of the above multi-step issues can be fixed with the use of a
shadow Matte material which allows the capture of shadows on a geometry without
the geometry showing up in the rendered output. Then you could render out an animation
sequence that had just the object and its shadow or a multi pass with obect and shadow, but no need for the object buffer.

Both MAX and MAYA, two tools which are mainstays in the Visual effects world have
this feature. It may be an old way to do it, but if it works and is easy it seems
useful.

I'm probably saying things incorrectly and I know my experience with this whole
concept is exteremly minimal therefore I am excited to learn different methods, but when I
compare two tutorials showing the difference between tools that are design to do the
same thing, I usually like the simplest. :)

Just want to make sure, that everyone understands I'm not trying to argue, really
have enjoyed the discussion and I am still learning so any comments are appcreciated!

MBW

Per-Anders
10-20-2008, 09:00 PM
My second post explains how to use multipass to get the result sans shadows on the original object, but you do not need to do this for what you describe as wanting to do.

To solve both your problems follow the advice already given:

Add a compositing tag to your groundplane and under "Object Buffer" enable the first buffer
Add a compositing tag to your "object" and ender "Object Buffer" enable the first buffer but set it to 2 (or just enable the second buffer).

Add a shadow pass in multipass
Add a "Object Buffer" pass in multipass with the Group ID set to 1
Add a second "Object Buffer" pass in multipass with the group ID set to 2

Render

In After Effects load in the composition fiel (if you exported) or just load in the multipasses
Set the Matte for the shadow layer to the Object Buffer 1 (the one that the groundplane had)
Set the Matte for the RGBA layer to the Object Buffer 2 (the one that the object had).

Composite however you wish.

mbw
10-21-2008, 05:06 AM
My second post explains how to use multipass to get the result sans shadows on the original object, but you do not need to do this for what you describe as wanting to do.

To solve both your problems follow the advice already given:

Add a compositing tag to your groundplane and under "Object Buffer" enable the first buffer
Add a compositing tag to your "object" and ender "Object Buffer" enable the first buffer but set it to 2 (or just enable the second buffer).

Add a shadow pass in multipass
Add a "Object Buffer" pass in multipass with the Group ID set to 1
Add a second "Object Buffer" pass in multipass with the group ID set to 2

Render

In After Effects load in the composition fiel (if you exported) or just load in the multipasses
Set the Matte for the shadow layer to the Object Buffer 1 (the one that the groundplane had)
Set the Matte for the RGBA layer to the Object Buffer 2 (the one that the object had).

Composite however you wish.

I think there is once again a mis-communication. I don't just want the shadows
on the object, but the shadows on the object and the floor.

For example: if I have a pile of blocks and the light is on the side, there would be
shadows on blocks and the floor. The shadow matte material would be placed on the
floor to capture these shadows in the same render as the object and object shadows.

Your above solution to use the object buffer1 as a track matte prevents the shadows
on the floor from appearing the AE output.

I have tried what you suggested and rendered all the files out just to see how they
hook together. I still can't seem to find a combination that gives all the shadows
on the floor and object and just the object no background. To continue the example I
am looking for a way to get the pile of bricks with the shadow on the bricks and floor,
but without any floor or background.

Another way of putting it: imagine You have two different scenes each with a
different background and spaceship. Supposed you want to composite both ships
with a 3rd different background in AE. Each of these ships casts a shadow onto
the planets floor in the original scene and you want that shadow. As of right now, I
can't figure out how to do this. There doesn't seem to be a way to separate the
ships and shadows(both on ship and floor) for each scene so they could be combined
with the 3rd background in AE.

The specular/diffusion/illumination doesn't work because the floor, which is necessary
to capture the shadows, is still in the rendered output. Using an object matte for the
ship causes the multiplication of the shadow map to produce edges around the object.
(at least in my examples, which could be flawed :)

Everytime I seem to get into compositing with C4D and AE I run into the same thing.
It seems impossible to get the data out.

Hope this helps with my communication. Perhapes I am just not understanding
what you are saying, but I trying to implement your suggestions so I am listening :-)

MBW

dataflow
10-21-2008, 06:04 AM
dont know if this is what your after but hope it helps someone

small eg.. of rendering light shadows for ae

http://3ddataflow.com.au/stuff/shadow.swf

Per-Anders
10-21-2008, 06:16 AM
I think there is once again a mis-communication. I don't just want the shadows
on the object, but the shadows on the object and the floor.

For example: if I have a pile of blocks and the light is on the side, there would be
shadows on blocks and the floor. The shadow matte material would be placed on the
floor to capture these shadows in the same render as the object and object shadows.

Your above solution to use the object buffer1 as a track matte prevents the shadows
on the floor from appearing the AE output.

I have tried what you suggested and rendered all the files out just to see how they
hook together. I still can't seem to find a combination that gives all the shadows
on the floor and object and just the object no background. To continue the example I
am looking for a way to get the pile of bricks with the shadow on the bricks and floor,
but without any floor or background.

Another way of putting it: imagine You have two different scenes each with a
different background and spaceship. Supposed you want to composite both ships
with a 3rd different background in AE. Each of these ships casts a shadow onto
the planets floor in the original scene and you want that shadow. As of right now, I
can't figure out how to do this. There doesn't seem to be a way to separate the
ships and shadows(both on ship and floor) for each scene so they could be combined
with the 3rd background in AE.

The specular/diffusion/illumination doesn't work because the floor, which is necessary
to capture the shadows, is still in the rendered output. Using an object matte for the
ship causes the multiplication of the shadow map to produce edges around the object.
(at least in my examples, which could be flawed :)

Everytime I seem to get into compositing with C4D and AE I run into the same thing.
It seems impossible to get the data out.

Hope this helps with my communication. Perhapes I am just not understanding
what you are saying, but I trying to implement your suggestions so I am listening :-)

MBW

Um, no my solution will give you :

a) One layer that just has shadows on the background, but no background itself and no object shadows
b) One layer that just has the object including its self shadowing, no background.

This is what you've asked for each time.

If you want the self shadowing (shadows from the object on the object), separate from the object itself then do as I said earlier using a blend layer. Seriously just try doing what I've suggested here, it gives you exactly what you've described as wanting.

Per-Anders
10-21-2008, 07:27 AM
To go with my post, here is the visual guide showing the whole process with a stack of books, and even throwing in how to make use of GI via a GI multipass in the shadows.

http://www.per-anders.net/general/howtomultipassshadow01.jpg

Simon Wicker
10-21-2008, 08:46 AM
hi per,

i think the problem is that there are two camps to this.

on one side are the compositing types (like yourself) who do everything in post. in this case you can use the multipass or compositing tags to find a solution that works in ps or ae.

there are also a group who do everything in cinema and wish to be able to do a final render (including the bg) with shadow catching. in this case you need to use the shadow catcher plug-in to get the right result.

i'm in the ps and ae compositing camp so it took me a little time to understand the situation.

cheers, simon w.

bobtronic
10-21-2008, 09:59 AM
Couldn't you just use a floor plane with frontal projected background picture and composting background tag? At least that what I did in this little example.

govinda
10-21-2008, 03:15 PM
Oh no you didn't just do that graphic lesson in compositing, Per. I'm knocked out. Is there a hall of fame for replies? Save the URL for this reply for every time this question comes up!

Constrict
10-21-2008, 03:41 PM
I was just about to say the same thing as Bobtronic with an almost identical example picture... So in other words, what he said :)

- Colin

vid2k2
10-21-2008, 04:13 PM
Lex had this solution.
Search for the thread, usefull info to what has already been posted.

mbw
10-22-2008, 12:43 AM
Per-anders,

Very much appreciate the graphic and I believe that is what I have been doing.
Attached are shots of my screen showing the issue with wired highlight using
the method you describe.

The three pic are:
* the diffuse layer showing the whole picture
* the green highlight that shows through on the edge of the sphere when composited
a green solid
* the actual AE layers.

If you look at the verticle edge of the blue box close to the sphere
you will see green has merged into the blue pixels as well.

Understand that I am not trying to piss ya off. What you propose in your
well documented posting is not hard to conceptualize. In fact, I had tried something
simliar to it before even posting my original question. I always seem to run into
this fringing issue so I presumed that I was doing it wrong. And that is where this
question of the shadow matte really started.

I have tried over and over again to get rid of the fringing to no avail. This is
why I'm keep coming off wondering how to do this.

Really do appreciate your help.

MBW

mbw
10-22-2008, 12:47 AM
Couldn't you just use a floor plane with frontal projected background picture and composting background tag? At least that what I did in this little example.

Bobtronic,
The idea is to get the objects and shadows separated from the background so that
they can be composited into any background with AE. Just using the frontal projected
background and render out the animation, would mean that anytime the background
changes the whole animation needs to be re-rendered in C4D. Much faster to just change
in AE. :-)

MBW

Per-Anders
10-22-2008, 12:50 AM
Try checking the "Shadow Correction" option on the Multipass Tab in the render settings in order to try and get rid of fringing (you can check it out in the Help documentation). Occasionally you will need to either defringe using a plugin or manually massage areas of a render in post, that's just part and parcel of compositing.

mbw
10-22-2008, 01:06 AM
Another example of what I am talking about. Here is a picture of
just the masking of the shadow map to get the shadows on the floor.

I use the object matte assign to the floor object as the luma track
matte for the shadow pass (in AE). The white line all around the
sphere causes the highlight. This appears to be the main issue
for my compositing cummies...

Thanks

MBW

Simon Wicker
10-22-2008, 06:53 AM
just use the method vid2k posted if that is all you want.

cheers, simon w.

Hilt
10-22-2008, 10:42 AM
I use the object matte assign to the floor object as the luma track
matte for the shadow pass (in AE). The white line all around the
sphere causes the highlight. This appears to be the main issue
for my compositing cummies...

Try playing with different Modes in AE (ie. multiply).
But yes, sometimes compositing can mean manual masking even when dealing with CG objects.

mbw
10-22-2008, 02:33 PM
just use the method vid2k posted if that is all you want.

cheers, simon w.

Simon,
vid2k's method of using the compositing tag set to "seen by camera=off"
seems to mean 1 of two things:

1) the tag is on the floor and then no shadows that hit the floor
are produced in the shadow map.

or

2) The compositing tag is put on the object of interest and this would require
two renders. One with the tag on and off.

I'm still experimenting with this idea?

MBW

Simon Wicker
10-22-2008, 03:05 PM
Simon,
vid2k's method of using the compositing tag set to "seen by camera=off"
seems to mean 1 of two things

no you should be using the 'compositing background' check box not 'visible to camera'.

apply a pure white material (in the colour channel NOT luminance) to the floor geometry and turn on compositing background. this will render as pure white but still capture shadows.

render this first with your shadow casting objects tagged to be invisible to the render camera to generate a shadow pass.

cheers, simon w.

Per-Anders
10-22-2008, 05:59 PM
Did anyone try the Shadow Correction option (that I mentioned before)?

mbw
10-22-2008, 07:03 PM
Did anyone try the Shadow Correction option (that I mentioned before)?

Per-Anders,
Sorry.. I did try your suggestion right after reading it. Didn't want flood you with
postings so I was working on a couple of ideas before replying. Anyway, turns out that
the Shadow Correction doesn't fix the problem, actually had no effect on my test case
still that same highlight around the edges. So after going back to the Steve Wright
book about compositing for ideas I got the notion below:

In the inital setup:
First the object is extracted from the diffuse pass using the object1 buffer.
Then the floor shadows are extracted from the shadow pass using the object2 buffer.

The resulting layers are stacked
Object only(normal)
Floor shadows(multiply)
background

This is just words describing what you have already explained, just rehashing the
steps.

But the problem with the highlighting my be the presumption that object2 buffer pass
hole is the same resprestation as the object1 buffer. Even if they are close, but not
exact then the difference would cause the highlight around the edges.

My, as yet untested idea, was to use the inverted object1buffer pass as the mask for
the shadow pass to get the shadows on the floor.

So layering in AE becomes:
diffuse_pass with track matte set to luma object1buffer(normal)
shadow_pass with track matte set to inverted luma of object1buffer(multiply)
background

I have got to test it yet, had to run out this morning...

What do you think?

Again.... THANKS for all the help.... I am very appreciative. This has been a
great learning experience for me.

MBW

Per-Anders
10-22-2008, 07:21 PM
You will need to expand/defringe the buffer pass that's used on the shadow, the problem is simply that while the pixel blend itself is fine and accurate it's adding 2 pixels at 50% at certain points around the edge, 50% overlay + 50% overlay = 75% overlay, not 100% as you might assume from simple maths so it never reaches 100% opacity, this can be exacerbated by certain AA algorithms that attenuate the AA in different manners, you can try using different AA to see if one results in a better result (though technically no AA at all should give you the best result, rendered at double res and then shrunk down in AE/PS).

Nanome
10-22-2008, 07:28 PM
Just curious, how are you interpreting your alphas in After Effects, mbw? Premultiplied?

Simon Wicker
10-22-2008, 07:28 PM
no monkey business needed, though, if you use the compositing background trick.

cheers, simon w.

mbw
10-22-2008, 08:04 PM
Just curious, how are you interpreting your alphas in After Effects, mbw? Premultiplied?

Nanome,
I'm just using the object buffer passes from C4D as LUMA Mattes so there isn't
any alpha. Maybe that is just terminology though. The Mattes are black and white
so there isn't any color from the background multipled in. Hope this answers your
question... I think it did.

MBW

Simon Wicker
10-22-2008, 08:07 PM
here.

compositing background scene.

cheers, simon w.

mbw
10-22-2008, 08:11 PM
no you should be using the 'compositing background' check box not 'visible to camera'.

apply a pure white material (in the colour channel NOT luminance) to the floor geometry and turn on compositing background. this will render as pure white but still capture shadows.

render this first with your shadow casting objects tagged to be invisible to the render camera to generate a shadow pass.

cheers, simon w.

Simon,
This is a 2 render step right? It seems that C4D should be capable of does this on it's
own though don't you think?

Thanks for the clarification of vid2k2's posting regarding the compositing tag.

MBW

mbw
10-22-2008, 08:15 PM
You will need to expand/defringe the buffer pass that's used on the shadow, the problem is simply that while the pixel blend itself is fine and accurate it's adding 2 pixels at 50% at certain points around the edge, 50% overlay + 50% overlay = 75% overlay, not 100% as you might assume from simple maths so it never reaches 100% opacity, this can be exacerbated by certain AA algorithms that attenuate the AA in different manners, you can try using different AA to see if one results in a better result (though technically no AA at all should give you the best result, rendered at double res and then shrunk down in AE/PS).

Per-Anders,
I am presuming you are talking about the matte chokers in AE right? Which one
do you prefer? I tried your idea of different AA last night and you are correct, the BESTAA
does produce a better matte than the geometry only AA. You know, I've read about the
50% + 50% <%100 but never really had the pleasure of getting first hand knowledge...
Oh well... expanding the brain is fun.

MBW

mbw
10-22-2008, 08:16 PM
here.

compositing background scene.

cheers, simon w.

Hey Simon,
Thanks for the file. I am not at my workstation right now, but will explore your
idea(would have done right when you sent it) when I get back to the computer.
Appreciate the help and C4D file. :)

MBW

Simon Wicker
10-22-2008, 08:26 PM
the compositing background trick is a two pass setup but it is a trade-off.

looking at per anders set up you have a single render but then the compositing is (to my mind) too complex. a very flexible solution but the precomping needed for the final result is a touch abstract for my tastes.

the two pass render is more complex to set up (would be easier if cinema had built in render passes but someone has come up with a render pass plug-in for c4d to help out) but the compositing is simply bg, mult shadows, object with alpha on top.

and if you wish to do everything in cinema then there is a shadowcatcher plug-in that makes objects invisible in the render but still able to accept shadows.

any of these methods is perfectly valid depending on your needs.

cheers, simon w.

mbw
10-23-2008, 03:48 AM
All,
Just a big THANK YOU to all involved in the discussion. I believe I have found 3 separate
ways to get an object and its shadows rendered out of C4D and into AE for compositing
with other Video.

Major point is that I don't want to do the compositing in C4D with a background and
floor(with frontal projection) which is the method that is shown on Maxon Training and Cineversity. It presumes I have the final background at render time.

Now a more specific THANK YOU to Per-Anders for his complete documentation of a
flow and Simon W. for sending me a compositing test file that I could use to understand
his idea for the flow. Also a THANK YOU to whomever it was that wrote the SHADOW
CATCHER plugin. This is indeed a cool plugin and should be included with C4D or at
least its functionality. (IMHO)

Now on to the 3 methods:

1) This is the most complex, but does give the most control in AE.
* Use a floor with a frontal projected texture. Attach a compositing TAG and
check "compositing background" option.
* Place object in the scene and attach a compositing TAG and assign a object buffer
number.
* Render out a multi-pass with at least diffusion, shadow, and object pass for the assigned
number in the above step.

Then in AE stack the layers in the following order
shadow -> with object pass as the INV LUMA matte (multiply blend mode)
diffuse -> with object pass as the LUMA matte (normal blend mode)
background

2) A little more complex on the C4D setup side and requires two renders, but
easier to composite in AE.
* setup all the objects and floor plane give them a compositing TAG
* Apply a pure white to the floor and check "compositing background" in the option
for the floor compositing TAG.
* Set the floor compositing TAG "seen by camera" to unchecked. This renders out the
objects with self shadowing but no floor and a complete Alpha.
* For the second render, set the objects compositing TAG option "seen by camera" to
unchecked. Then set the options for the floor to have the "seen by camera" checked.

Then in AE stack the two layers
render2(multiply blend mode)
render1(normal blend mode)
background

3) This is the easiest but doesn't provide as much flexibilty in AE
* Install the shadow catcher plugin
* create a floor under the object and assign the shadow catcher shader
* Turn off everything but object and floor to render using the red/green/gray dots in the
object manager
* render

Then in AE the stacking order is
rendered file(shadows and object in one file with an alpha defining the transparant areas)
background

Obviously these methods are not all inclusive, there are probably dozens of other ways
to implement the idea of generating CGI elements in C4D to be used in compositing. I
just wanted to figure out a way for me to get it done and now I have 3. :)

Once again thanks to all who helped out. I guess that means I'm buying the first
round at the C4D->AE compositors group meeting. :thumbsup:

MBW

parallax
10-23-2008, 09:27 AM
Christ, what a pain in the ass. I'm struggling with this right now, one of many things that should be much easier.

Simon Wicker
10-23-2008, 10:20 AM
i fail to see how it could be any easier than the various methods that have been outlined in this thread but feel free to actually contribute something positive.

cheers, simon w.

joshfilms
10-25-2008, 03:59 AM
This way works for me as I stated in my previous post if you don't want to do a separate render.

shadowcatcher plugin
http://www.grafxflow.co.uk/forum/index.php?topic=161.msg427

mbw
10-25-2008, 03:39 PM
This way works for me as I stated in my previous post if you don't want to do a separate render.

shadowcatcher plugin
http://www.grafxflow.co.uk/forum/index.php?topic=161.msg427

Josh,
I agree shadow catcher is very easy and seems like this functionality should
be included in C4D. One note though, shadow catcher didn't seen to catch the color
of the shadows. So if for some reason your shadow was set to red, the shadow
catcher would still produce black shadows. In this case you would have to use
one of the other methods.

MBW

vid2k2
10-25-2008, 04:20 PM
Josh,
I agree shadow catcher is very easy and seems like this functionality should
be included in C4D. One note though, shadow catcher didn't seen to catch the color
of the shadows. So if for some reason your shadow was set to red, the shadow
catcher would still produce black shadows. In this case you would have to use
one of the other methods.

MBW

Wellll, that's not necessarily so.
If you set the mix mode to multiply and set the color to red
... you get a red tint shadow. Don't forget the alpha.

This was a file from 2003 rendered in v9.6. HTH

Edit: If you just want red in the shadow, then adjust the shadow color of the light.

mbw
10-25-2008, 10:41 PM
Wellll, that's not necessarily so.
If you set the mix mode to multiply and set the color to red
... you get a red tint shadow. Don't forget the alpha.

This was a file from 2003 rendered in v9.6. HTH

Edit: If you just want red in the shadow, then adjust the shadow color of the light.

vid2k2,
Thanks for the info. Didn't know about the multiply in the color channel. While
that isn't the same as a full on colored shadow it does give a good tint. Not sure
what you mean by your edited statement though because this is the original
issue I mentioned.
If I have the light set to produce red shadows, the shadows captured using the
shadow capture plugin are still black at least in my test cases. Not a big deal because
rarely do I see red shadows in the real world;) , just noting the issue.

MBW

vid2k2
10-26-2008, 12:16 PM
Without you posting a file, we'll continue going in circles.

"IF" you want a color shadow only, other than black, it's done in the manner shown.

Good luck to you.

mbw
10-26-2008, 03:48 PM
Without you posting a file, we'll continue going in circles.

"IF" you want a color shadow only, other than black, it's done in the manner shown.

Good luck to you.

Hey why do you seem so upset? No worries here.... There other ways to
get a shadow matte and color it so desired. Attached is the tescase that
I was working with:

Cube to cast shadow
Plane1 with shadow catcher plugin( I used your idea of multiply to color)
Plane2 with default texture a little lower on the Y axis
Light with raytraced red selected(well burnt organe anyway) shadows.

When you render the window, you will see that that shadow caught by the
Plane1 is no where near the color of the shadow cast on to Plane2. If the
multiply isn't used, then the shadow caught is black.

If for some reason, someone wanted red shadows and was using the
shadow catcher plugin, for compositing, this would cause problems.
They would have to use one of the other methods to get the shadows.

Hey no worries here... I readily admit that "I dont' know" is my answer to
a lot of "how to questions". I'm trying to just use my observations to
enhance discussion. So far this thread has been a GREAT one for my
learning.

Hope this testcase explains what I tried(bumbling) to say in the original
posting about shadow catcher and colored shadows. If I am missing
something I'd be happy to learn it too. :)


MBW

vid2k2
10-26-2008, 05:59 PM
No problem here, nor am I upset. Just posting options.
It takes time to learn a program. Keep at it, you'll be fine.