Cineversity

Hi, I have attached a file, hopefully successfully. I can see DOF in editor window, but not in multipass. Also, and this probably has something to do with this, but in singlepass in picture viewer, I see the layers have an “eye” icon, but depth does not, please explain, because I am clueless ; )   
https://dl.dropboxusercontent.com/u/31514862/009_product_final-CZ.c4d

Hi Craig,

The set up that you have is pretty large. The spray-cans are larger than an average human is. The settings are for a wide angle lens. I can see you like to counteract both [?} with a F/0.1.

If the results works—the numbers are of minor priority ;o)

Depth Pass. This is an information channel. Not an image channel. Each pixel, if the camera is set up, represents one single measurement in space. Hence why it never should be Anti-Aliased for example. It is since the late ‘90s a discussion that comes up from time to time, but oversampling is the only answer here. I mentioned it, as the HD settings is given in both, your Product as well as in the export (Ausgabe). For any use this channel needs to be at least in UHD or better the 8K version of it. Yes, there is a lot of nonsense on the web about this. Please ignore it. Information passes loses their usefulness if calculated with AA. The quality would be weak, to say the least.

The reason why it has no “eye” symbol is given in the fact that it is an information channel, like a normal pass or a position-pass. It is, again, not an image pass, so it doesn’t calculate inside of the Multi-Pass representation.

The Depth path is based on settings of the camera {detail] and optional based on Render-Settings. It has NOTHING to do with the physical camera nor is in sync with any of its setting regarding DOF.

Real DOF goes though glass, smoke, mirrors, etc. in other words, sometimes it contains several layers of depth per pixels, which is not possible with the “depth pass”. To AntiAlias these several values is not possible. Hence why “Deep Compositing” was invented a while ago, but not available so far here.
One of the main problems with 2D is based on the fact that with a sensor size we leave the idea of an one ray per pixel only. Which is more complex. Hidden objects can become visible again…etc. However, the main problem is DOF and motion blur, which is not solved in compositing with 2D representations. It never will.

DOF is certainly anchored in photography/cinematography and not originally in 3D. The understanding and its implementation of it is retrieved from practical measurements and examples taken with typical lenses. Since Cinema 4D has changed the idea of Units to real world measurements based on many needs, e.g., dynamics, the DOF settings follow real world measurements. To set up things ten times larger makes everything a little bit more complex, but yes sometimes it makes more sense. I’m not certain if a spray can in, e.g., “20+ cm” would be more complicated ;o)

The differences between a 3D based DOF (shallow/bokeh) and a 2D based (post and plug ins) might not be visible always, but most of the time an educated eye can spot it a mile away ;o)
Since million of peoples are now into professional photography, this educated eye will be more and more standard, to say the least.

I hope I could clear your question and as you requested, “explained” it. Let me know if you have any questions. I do photography with SLR since the late ‘70s, and have recently published nearly 200 tutorials about—for 3D artists, see below. All well researched and based on long time practice. (... and I avoid the typical trap to extrapolate knowledge from analog photography, which is a different beast all by itself)

All the best

Images, this is the MP, and it looks OK. You can also see that the Depth pass is black, which is explained in the image on the right, this information pass is not set up, [not adjusted later in the render setting options]. The second camera has a set up for it, I saw that! :o)

P.S.:

Some more information, as I like to share how I tested the initial version of Physical Render [PR] and its DOF [shallow} abilities, especially with the 3D vs 2D data in mind. I hope that makes it more clear why I prefer the PR over any post production method.

http://old.cineversity.com/forum/forum_posts.asp?TID=2720&PN=1&TPN=11

Scroll down… R13 splash screen is the separator here.
... and following page, there you can “see” how 3D and 2D are fundamentally different in DOF.

Yup, it is around four years already. Time is flying.

Hi Dr. Sassi, thanks for the indepth reply. I am still not clear:
  Are you suggesting that since my models are too big, I should use one of the C4d/supplied figures as a reference ( assuming ave. male height is 6’ ) and reduce my scene relative to a standard 6’ figure?
  Also, is that why my depth pass is black?
  I see your screen capture for the standard render, I ,like yourself prefer the PR
  I want to render a short animation, so that is why I am obsessed with the depth pass not looking usable. Th epr is more logical to me. I did photography in college, in the jurassic period ( ) so I’d prefer to use pr. Please let me know, and thanks for your sage advice!

Hi Craig,

If you model along the real size of things, you have more luck with the set up of the camera, to achieve a closer approximation to practical footage.
The standard figure in Cinema 4D is since ever out of reality, no idea why. It is 600cm, close to 20’ ;o)
If I take your camera [camera.angle] then there is no set up for a depth pass. In Camera.2 there is of the back, but if only for the back you might run into problems eventually.
The render in the capture is from your PR settings, not the standard.

Great that you took Photography in College, I think it is one of the most essential things to have as a 3D artist.

The reason why we have a depth pass is certainly to find around the same time jurassic period in time, when computer where slow. Hence the need to fake it. It is fast and wrong at the same time. The DOF blur/bokeh is used these days often to show off without any idea what it finally supports, i think with your background you can follow. Some think the more the better. But an image is a communication, and the background or foreground can have an essential part in this information. To just blur it has a meaning and with that, one changes the overall message of an image. For some it looks filmic and so they dump it on everything, only to miss the point of it to 100%.
To use it as a color or an element in your “Mies en Scene” is essential. I know, most people have perhaps already stopped reading here and switched on a plug-in instead. ;o)

The downside of the PR rendering is, it is not fast nor easy to set up as the 2D fake of it. For an animation it might have some mostly time-econimc issues as well, besides the time to set it up, i have the time for the rendering here in mind. So, always PR? Nope. It must be an artist call. With that, you personally need to know what your target is. If you have followed my integration series here on Cineversity, you might notice that I put quite some time on Light-Wrap/Light-Glow. This can be done in C4D directly with Chan-Lum (Channel Illumination—to the best of my knowledge), but it is—again—much faster to set this up in 2D. I use it all the time in my work, especially for mixing practical footage and 3D renderings. As we go towards REC 20.20 with UHD and with that to an possible hi-res hdr based information, as well as a large gamut, anything that is not well done will show up like a sore thumb in the future. Again, artist call. It is certainly always a question of how far one likes to push it, or how far s/he likes to go. On the end, there is no excuse, there is only visible what was delivered.

If you can, push it as much as possible, time moves fast and things a few years ago look already old and CGish.

If you don’t have the time, perhaps you can render the blurry background once and use it as texture, if you do not apply a “rack focus” for example, or changing of light. (both can be blend as well, as shown in the link above with the post from 20 August 2011 at 7:41pm. It is always a trade off, balance or evaluation of the artist what to do, optimize or pay in render time.

Let me know if there is another question.

Have a great weekend

P.S.: I double checked everything, nothing has changed: the Depth Pass and the PR Rendering are independent results of different settings. What will influence the Depth Map/Pass will have ZERO effecto on the PR DOF effects, and vice versa. Both are also not easily mixable later in post, it rather advised to avoid it.

Hi Dr. Sassi, thanks again. Yes, when I took photograph in college, RIT, from 79-82, I took also 3D design. Being the foolish kid, I thought, “why do I need these courses, I just want to illustrate. As I started to grow up ( but not too much) I appreciated the value of learning photograph. Fast forward to within the past 15 years, only then did I appreciate 3D as well. 3D packages have more in common w/photo. and 3D design then pure 2D ill. but they are all related, as you know.
  I did a test w/my angle camera and the other camera. Yes, the angle offers no depth info. is it the angle that I am using? thanks for your insights, stay well, Craig

Craig, right, most knowledge is not directly taught because it is applicable 1:1 later on. Hence why some people think- why do I need more math than I can learn in one day. ;o) It is first of all the structure that those things deliver. Mathematic allows your brain to see differently. Secondly, to know other art-forms allows to see your own art form much clearer. I have no understanding that some people avoid knowledge. But that’s just me, learning my whole life. But I just stopped reading a book, one of the many hundreds I have read about filmmaking. He suggest to start with three point lighting. A clear indicator that he never was in the past fifty years on a film set. No-one in his/her right mind starts with three lights at once, and there I can understand why people get tired of learning. Bad instructors. They ruin it for everyone.

Knowledge set one free, and helps avoiding to be manipulated.

When it comes to photography, and hence my introduction paragraph above, there is a lot of misunderstanding published in books, and even more so on YouTube or the web itself. But the lenses in combination of the film-gate/sensor size have something that can be calculated. Well, I would say to a certain degree. There are lenses which have a fast falloff of the blur/bokeh and some have not. the wider the aperture is open, the more glass of the lens is used. As it is a construction, the curve of the glass can be deliberately different. If I take all my ~50mm lenses (I have a lot) and compare them, they have all a different characteristic. Hence why I never understand how to check only sharpness/resolving power in a lens and be happy with a single one. Take the Lensbaby Velvet 54, an old Zeiss T* or a Sigma Art DG, three completely different lenses. In film we would suggest Cooke, Zeiss and perhaps a Leica to get three different aesthetics. OR different aperture shapes I have developed: https://www.youtube.com/watch?t=15&v=lifpmsiid0Q

It all plays into the DOF and it can’t be just calculated. But to get an estimate—those formulas are in use. With the 12m and 29m distance in your set up, only with an F/0.1 some kind of effect was visible. The formula for aperture is based on the focal length, but only relative. It is not a real physical measurement (again, ignore the web). Where the aperture sits in a lens, the glass elements are mostly the smallest of the group, so it is realtive to magnification, etc. But I go to far, … only to show you that it is kind of complex.

Yes, the short answer, if you would have focused on the cans, you would have been at the “hyperfocal” point with an typical F/2.8. Which means everything after the cans would have been sharp. Not so much with a not in existence F/0.1 set up. (You could have also increased the filmgate/sensor size to get something closer to your scale… :o)

There are cheap DOF calculator apps available—or take a look at this one http://www.red.com/tools/depth-of-field
It might helps you easily to get what you want.

My best wishes