C4D object buffer for luma matte is smaller than the area to be masked


#1

white line should not be there. I don’t understand what I’m doing wrong.

Render from c4d with object buffer, one pass, the mate that in theory should mask the “screen” in ae. Instead I get that huge line (the grey/white line is the screen color behind the composition who holds the media in ae, I put a black solid so is easier to see)

practically the pass that should mask the screen when used as luma mate is smaller by a few pixel than the area to be masked.

render with antialiasing, if I turn the render off, then the line disappears but I have the antialiasing problem (jagged lines)

What to do?

image was cut from a 1080 frame, is the actual size


#2

What king of format do you output for your multipass,(png.jpeg?)and do you have motion blur enabled ?Also in the compositing tag you have an option to force antialiasing…


#3

It’s a premultiplication issue. Generally, when you produce a matted image, there is the matte part and there is the fill. The fill is unpremultiplied, so that you don’t get a line around the edge. In the case of a very blurred circle, the premultiplied fill has a nice soft edge, but the unpremultiplied fill is a solid yellow with a hard edge at the extremity of the blurry matte.

However, when you produce an object matte in Cinema 4D, the fill part is premultiplied… or the fill might even be a fully composited image. The line is a natural side effect.

You’ll sometimes see the line particularly strongly if you use an alpha material that’s a lower resolution than the main material.

Just use a little bit of matte choker (and do motion blurring / DOF at the compositing stage).


#4
flashato said

What king of format do you output for your multipass,(png.jpeg?)and do you have motion blur enabled ?Also in the compositing tag you have an option to force antialiasing…

I was exporting to TIFF (and tried PNG also) No motion blur enabled and the force antialiasing didn’t work. And that because I’m THE KING of the idiots. Big lesson learned today.

If you have a bug at the end of the day, close the computer, go the sleep and fix it tomorrow. Don’t try to render 42 different combinations of 10 frame animation till 3 in the morning to find the solution. Because you will mostly probably fail to see the obvious simple error.

Wake up this morning, fire up the machine, opened C4D and instant revelation. Incredible how the human brain works but it surely need to be rested else it will fail big time.

Do you want to know what the problem is and how stupid I am? :expressionless:

Used a material with luminace enabled for the screen. Yes, I’m really that stupid. :confusedsad:

Thank you for your help flashato and felt_tips, I really appreciate it. :slight_smile:


#5

while I’m at this. Linear workflow is activated in C4D, I checked the “Linearize Working Space” in After Effects. I’m doing this right or I’m heading to some other problems? Also I render to 24 f/s. This is for a project on videohive.


#6
doru said

while I’m at this. Linear workflow is activated in C4D, I checked the “Linearize Working Space” in After Effects. I’m doing this right or I’m heading to some other problems? Also I render to 24 f/s. This is for a project on videohive.

no bother, I don’t have time to figure this out for the current project. :slight_smile:


#7

Don’t work in linear unless you know what you’re working in linear for.

In short, it represents the actual light intensities, before the gamma curve is applied to make it look like what we experience (yep… our eye has a gamma curve too!). This makes light on light interactions more believable… motion blur too.

It can take a bit of getting used to if you’ve always worked with 8 bit gamma adjusted footage… which until computers get quite a lot faster, is most of us.


#8

Why would one work in linear? I’ve heard it is preferable to get used to that color space. What are the (dis)advantages ? I’ve read quite a few articles on it but still can’t come up with grounded opinion.


#9
felt_tips said

Don’t work in linear unless you know what you’re working in linear for.

I have no idea what is for so I should study this better to understand what are the advantages.

InlifeThrill said

Why would one work in linear? I’ve heard it is preferable to get used to that color space. What are the (dis)advantages ? I’ve read quite a few articles on it but still can’t come up with grounded opinion.

I found this video that should answer some questions.


#10

:slight_smile: Nick is great. However, he passes information through his personal understandings on the subject thus there is a chance he could be easily wrong. This does nor work for me. The podcast by fxguide is probably the best one I’ve hear on the subject so far as well as the stuff at Tim Clapham’s site. Recommended to all.


#11
I’ve hear on the subject so far as well as the stuff at Tim Clapham’s site
Agree.

#12

To understand linear, you need to understand what a gamma curve is.

Here’s how I’ve always understood it… Recording devices and playback devices (and the eye too) don’t respond linearly to light. So for a video camera, double the amount of light hitting the chip doesn’t make for a pixel that’s twice as bright in the final image.

What we generally work with are gamma corrected files, so they look right. But what that means is that when it comes to adding light together, the results are skewed, because we bent the files to make them look right.

The upshot…? When you do additive operations, like motion blur it doesn’t look like when you shoot it in camera. You may have noticed that when you shoot bright lights, the motion blur feels very different to After Effects motion blur, for instance.

So how linear works is instead of gamma correcting the footage for the outset, it keeps a linear file, where a doubling of the light does mean a pixel that’s twice as bright. All operations work on the linear files, so if you add two pixels together with a value of 0.5, they will make 1… and after the math has been correctly performed on the linear file, the gamma curve is added back on afterwards.

Why it’s tricky:

If footage is already linearized, then you need to have it’s color space (or force one on it). Also, you’ve gotten used to color correction working a certain way… and it feels completely different in linear workflow. And finally, because when you hand off files to people in linear color space, they always think you’ve done something wrong. :slight_smile:

I think working internally in linear for 3D is pretty imperative. For visual effects it can be very important in terms of matching CG stuff to the look of a scene. If you’re working on a project that uses a lot of lights to create a cool naturalistic effect, then it’s worth using linear, but for standard motion graphics stuff, you’re generally just adding a stage of complexity in that isn’t entirely necessary.

Does that shed any gamma corrected light on the matter? :smiley:


#13

I see. So as Cinema defaults to linear, this suggest rendering out files that can embed this color space and bring it over to AE, I am guessing tiff, exr, tga… This will result in switching to linear in AE as well and finally rendering a gamma corrected file.

If linear is switched off in Cinema, well we cut the extra step in AE, right? Making sure I got it right :slight_smile:


#14
InlifeThrill said

I see. So as Cinema defaults to linear, this suggest rendering out files that can embed this color space and bring it over to AE, I am guessing tiff, exr, tga… This will result in switching to linear in AE as well and finally rendering a gamma corrected file.

If linear is switched off in Cinema, well we cut the extra step in AE, right? Making sure I got it right :slight_smile:

Since when has Cinema defaulted to linear? (is that linear output or linear internals?) I’m still on R12. Haven’t gotten around to upgrading yet.

After Effects can also linearize files. You don’t need to render linear files out of Cinema necessarily.

I’m on shaky ground here though now. You’d need to ask someone who uses linear more than I do for the low down on practical details.


#15

That’s alright. It’s been helpful. Thanks.


#16
InlifeThrill said

That’s alright. It’s been helpful. Thanks.

How long you been plutonium?


#17

Is on by default in C4D and I see no reason to turned off but before using the image in after effects you need to change the color profile in the save options (under the file type)


#18
doru said

Is on by default in C4D and I see no reason to turned off but before using the image in after effects you need to change the color profile in the save options (under the file type)

Which version?


#19
felt_tips said

Which version?

r13


#20
doru said

Is on by default in C4D and I see no reason to turned off but before using the image in after effects you need to change the color profile in the save options (under the file type)

Correct! But unfortunately files size will be enormous too, which leads to impossible use for VideoHive. I’m finishing new project now and I had to convert it to 8 bit format, because size of c4d linear footages is 6 gb :smiley: No way reviewer won’t let through this :slight_smile: