Cineversity

Hi Dr. Sassi, I know, of course that this is a C4D forum, but I have a question concerning C4D integration w/After Effects , specifically where to place the depth pass in After Effects. I feel that I am SO close, yet, not quite there, would you mind if I asked here?

Hi Craig,

The use of a depth map might be not limited to a single target. What do you want to do with it. Is a shallow depth of field effect your target, or is it more a “Sfumato” (z-perspective/haze), perhaps just a depth matte to separate objects in space.

It follows of course my “little” text of data passes and should NOT have Anti Aliasing applied to it. Which results in some extra work, as the depth matte stores the information of a distance per pixel. It can’t store several values. If Anti Alias is active or just oversampling as some suggest, the distance of in the matte will be BETWEEN the objects, which results (based on the target) in more or less horrible artifacts. The greater the distance among the object, the more this will show up.

Camera Lens Blur effect, would be certainly an effect to look at, or if your material is not in float, perhaps the plug in from Frischluft “LensCare” is an option. It is from my experience the way to go. http://www.frischluft.com/lenscare/index.php.
If used with “Camera Lens Blur effect” you need to set the depth pass as information (no AA!)—and that is given as pulldown menu in the filter.

Haze would be normally done with the depth path connected to an adjustment layer or as “TRKMAT” with two layers of the same footage and one is adjusted for haze.

Distance mask are adjusted depth mattes like pulling a key of a certain gray-value.

All the best

Sassi

Hi Dr. Sassi, before I get into it, I have heard the term ” Sfumato”, in regard to portraiture, as in making one’s hair soft, or “smokey ” , so the eye focuses in on the face, live and learn. As far as using depth of field in AE, I know to use the depthpass in C4D. When I am in AE, I import the AEP. In my timeline, I drag in the depth pass. I have used the “compound blur”, which I drag on to the depth pass layer in my time line. In the compound blur pulldown menu, I select the depthpass. I did a one-on-one with Darrin, and it worked great, but I unfortunately did not save the file to review ; (-now, I’m frustrated. Obviously I am doing something wrong in my workflow, because I am not getting the results I desire . Imagine if you are in a tunnel, with a man in camera view. I want my tunnel to show depth of field, with the man in focus, does this make sense?, thank you

Hey Craig,

For me Sfumato is mostly the haze in landscape paintings, where it makes naturally sense.

Dictionary:
sfumato |sfo͞oˈmätō| noun Art
the technique of allowing tones and colors to shade gradually into one another, producing softened outlines or hazy forms.

Anyway, shallow depth of field based on a depth matte is on the end a simulation and should be not overdone. I think we are all very spoiled from the “Physical Render” in r14 with its very nice results.

The compound blur is possible but the idea of the compound blur is based on a gray map, to specify areas for blurriness. The gray-values have to fit and is not targeting depth of field effects here.

Closer to a photographic result is the camera-lens-blur, and it has certain adjustments that makes it the best choice of default methods in Ae. First of all you can adjust the focus point, which is not a given in the compound blur. Then you have the iris properties and to get a little bit closer to Linear Scene/Light, the Highlight part, which allows for an threshold, to boost even low energy highlights to bloom.

However, that comes with a cost and that is based on quality. If used only to a certain degree, it might work nicely. If you need a shallow depth of field, my suggestion would be to split the scene in foreground, middle ground and background, and blur those areas independent.

A treatment as I mentioned it in the Integration 101, in terms of Light-Wrap helps certainly to overcome some short-commings as well. But, that should be done before the blur starts to achieve a good quality.

If motion blur is needed, this split in three (fore/mid/back) is perhaps necessary, as this is a situation based problem/solution, that is nearly impossible to solve otherwise. Hence the beauty of the Physical render, but its problems to be useable for Multi-pass.

Anyway, before you start longer renderings, ALWAYS make test set ups. If a lot of camera blur is needed, perhaps even four times the resolution is needed.

Perhaps you make a little example scene, and a Photoshop mock-up what you like to have.

If you can separate the man from the tunnel, I certainly would do that, and compose it later. Especially if the man has the silhouette against the bright light from the end of the tunnel, this needs a light wrap as most lenses will not get that contrast sharp, ad we are used to see it in that way.

Blur is always based on neighbor-pixel information (pixels for digital…)
The main thing to understand is, that you have in reality the scene projected to your sensor (or film if you like). This results in a certain size for your scene. Compare that with the size of the lens, and you might see how large the lens is to that captured image. In that moment it becomes clear that the sensor can see more while filming. So it can practically see behind an object to a certain degree and in that way you “see” the blurriness of an object even partly obscured by another object.
IF the image was done from a pin-whole camera, and nothing else is given in C4D with Raytracing/Phong renderings, this obscured information to get a nice blur from a partly obscured background object is not possible anymore. This option is gone. And with that, there is no magically trick to get that data back. Hence all sDOF (shallow depth of field) blur is quite limited. The C4D physical rendering overcomes this as it has the data in the scene.
Then comes the problem with the depth map, as it should NOT be AntiAliased, you need to up-res the whole compositing to render the blur in a sub-pixel precession, to get then your target format to a certain degree working. I’m NOT a fan of simulated sDOF from flat 2D data, and if then only to a certain degree.

So, if you set your “man” to invisible for the camera, but visible for the rest of the scene, you can split this. In this way you get a fantastic blur for your tunnel, as all the data is available, and then place the man into it in “post”. use a Light wrap if light comes from the back to really integrate him. If you ahve motion blur (a little bit) apply it now. Then color correct and do other finishing steps.

Again, quality has its price and “fix it in post” is not always the best idea.

All the best

Sassi

Thanks Dr. Sassi, a lot to absorb, thanks for your insights, again ; )-Be well, Craig

Hey Craig,

Certainly it is. If I get a correct picture from the post above, you expand from 3D to compositing. Compositing is considered a job position in studios, and it is not just a simple “slap” stuff together, if you aim for quality.
To support such work, I have had created the Integration series with a lot of details, but also some years ago a series about multi pass rendering, and some of the standard problems there.

You might find that each project has its own challenges, but after a while it all looks more or less familiar. In the “JET Making Of” series, you find certainly some similar problems discussed. This is a lean back and just watch series. The idea is, to see and follow, and then apply it in your own project. If that works, you know that you are a step further. I avoided here the “do-this—do-that” approach, as it has not really proven to be long lasting.
It works only with a forum on your side, to be able to shoot those question, so you don’t get stuck. Let me know if you need anything else.

I can suggest as well some books.

Have a great weekend

Sassi

P.S. I have added a little bit to post #3 (my second post) to describe a little bit more why 2D sDOF has short-comings. If that is not understood, one might not know why things look artificial. hence my suggestion to split the man form the tunnel, see my tips above.

To made that point more clear, when we got the options in r13, I had set up some tests here:
http://old.cineversity.com/forum/forum_posts.asp?TID=2720&PN=1&TPN=12
The simple idea was, if you place a red sphere behind a gray sphere, so that you “just” cannot see the red sphere: a real camera with a wide open lens would get a red “rim” around the foreground sphere. This is NOT possible with a depth map. Hence my discussion about. I was clearly happy when r13 introduce this fantastic option. Since then I have not once used 2D simulations of that effect in production. I’m not able to enjoy it anymore, since I know I can have it so much better now. But that just me, and paying the render-price for that is another story… especially if one likes to work in 4K from now on—it seems pretty much impossible for independent productions. Which means, I stick with my tip, if good quality is needed, one might need in some cases to split up the scene, to overcome limitations. Man in tunnel sounds like a good option for that.