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Pros and Cons of Carrara DOF Vs. Postworked DOF
Posted: 08 February 2013 04:10 PM   [ Ignore ]
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I’m starting this thread because there was a discussion about postworked DOF Vs. Carrara’s DOF. I didn’t want to hijack the thread, so I’ve started a new topic.


Please feel free to add to this thread. This thread isn’t advocating one way or the other as clearly there can be advantages to knowing how to use both methods. Also, feel free to post any advice or tips on how to get the most out of either method.


I’ve used both methods with varying degrees of success, and there are pros and cons for both. The biggest pro for me is the time savings of using a depth pass in Photoshop to generate the DOF.


A big con for the depth pass is the lack of respect for alpha channels, hair, and volumetric effects. I’ve come up with pretty quick methods to edit the depth pass in Photoshop so it’s not a deal breaker for me, because if it’s a large resolution, complicated image, many times I could be done editing the depth pass before Carrara could add the DOF internally.


Besides the time involved with Carrara internally applying the DOF, another big con for Carrara’s DOF is that sometimes the preview’s DOF doesn’t match the finished output, which means if you’re unhappy with it, could be stuck re-rendering your image.


I’m posting a couple images of the same scene where I’ve edited the depth pass in Photoshop to correct for the depth pass not respecting the alphas used in a particle generator.


First up, is the straight image, followed by the unedited depth pass. The next image should be the edited depth pass and then the complete image with postworked DOF. Please note that I inverted, equalized and adjusted the brightness/contrast for the depth pass because I wanted an exaggerated effect.

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Posted: 08 February 2013 04:57 PM   [ Ignore ]   [ # 1 ]
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Any clever workarounds for when hair is used? For me, that is the biggest to drawback creating DOF in post.

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Posted: 08 February 2013 05:41 PM   [ Ignore ]   [ # 2 ]
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The render I mentioned previously—the rendered DOF passes appear to have been lost (despite my propensity to save many/most/all in-progress render results) or perhaps done on a different system. Probably quickest to re-render it between troubleshooting renders for why Carrara keeps segfaulting on my current project.

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Posted: 08 February 2013 05:55 PM   [ Ignore ]   [ # 3 ]
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What I do is use the poly line (I think that’s what it’s called) selection tool and outline the hair in the color image. I feather the selection maybe one pixel (depends on the image resolution and other factors), and then go to the depth channel and use the eyedropper tool to match the level of gray/black and fill in the selected area.


I did this picture awhile ago. This one was a bit more complicated due to the wispy hair, but it still took less time than the internal DOF. I was going to try both methods with this one, but I became impatient and canceled the job before it was done and just finished the render with the depth pass.

 

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Posted: 08 February 2013 06:03 PM   [ Ignore ]   [ # 4 ]
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I guess I should add another con to Carrara’s DOF as well as most of it’s post effects (as of version 7.2 anyway) is that they’re not multi- threaded or able to be done with render nodes. That bums me out as that could speed the process up greatly.

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Posted: 08 February 2013 06:22 PM   [ Ignore ]   [ # 5 ]
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agreed about the non-multicore. Totally bogus. I’ve noticed that your images are all fairly shallow and so wouldn’t exhibit the problems I saw with my scene.

For some purposes even this would be fine (and faster) to do in external post (in particular I’m thinking of animation where the time per frame is even more important), but (especially for a high resolution still) there is a significant difference in the quality of result—and that is just using the low quality DOF setting.

This was with camera1, I don’t remember now where focus was set on this one and I forgot to turn off alpha channel and pre-multiply.

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Posted: 08 February 2013 07:28 PM   [ Ignore ]   [ # 6 ]
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I haven’t seen any of the post filters use multiple cores. Not even Toon
EP, does it bother you that I linked to this in my Tutorials section? If it does… I’ll be a good little guy.

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Posted: 08 February 2013 07:31 PM   [ Ignore ]   [ # 7 ]
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evilproducer - 08 February 2013 04:10 PM

I’m starting this thread because there was a discussion about postworked DOF Vs. Carrara’s DOF.

...and I was being stubborn about it.
I’m here to tell you Sir Evil…
I am sold. From now on, I’ll be animating to sequenced frames just in case tweaks are needed.
For those who might not know… I’ve always kind of refused to do post. Well EP has finally beaten me into a pulp… I mean… into submission… yeah that’s it… submission!

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Posted: 08 February 2013 08:24 PM   [ Ignore ]   [ # 8 ]
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evilproducer - 08 February 2013 05:55 PM

What I do is use the poly line (I think that’s what it’s called) selection tool and outline the hair in the color image. I feather the selection maybe one pixel (depends on the image resolution and other factors), and then go to the depth channel and use the eyedropper tool to match the level of gray/black and fill in the selected area.


I did this picture awhile ago. This one was a bit more complicated due to the wispy hair, but it still took less time than the internal DOF. I was going to try both methods with this one, but I became impatient and canceled the job before it was done and just finished the render with the depth pass.

 

Thanks for the reply. That works fine except for close ups, especially if there is any detail behind the hair. I have tried using the hair as grass, and it often causes problems, especially when trying to exaggerate the DOF. I use Photoshop CS6 and the lens blur feature is finally64 bit. Now it is very fast compared to rendering.

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Posted: 08 February 2013 10:04 PM   [ Ignore ]   [ # 9 ]
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The post-render filters are called from a single entry point.  It would be up to the post-renderer to do the actual threading, unfortunately.

I’ve been looking into this as part of the HDR export attempt.  I am getting VERY annoyed at certain internal assumptions that go on around the renderer - the only way I can get any 32-bit data out of the renderer (short of writing my own mad ) is a post-renderer - and only SOME information is passed as 32-bit dat

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Posted: 08 February 2013 11:10 PM   [ Ignore ]   [ # 10 ]
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Dartanbeck - 08 February 2013 07:31 PM
evilproducer - 08 February 2013 04:10 PM

I’m starting this thread because there was a discussion about postworked DOF Vs. Carrara’s DOF.

...and I was being stubborn about it.
I’m here to tell you Sir Evil…
I am sold. From now on, I’ll be animating to sequenced frames just in case tweaks are needed.
For those who might not know… I’ve always kind of refused to do post. Well EP has finally beaten me into a pulp… I mean… into submission… yeah that’s it… submission!


Dart, it is absolutely fine if you wish to link to this thread. It’s not my forum. Technically I know it’s Daz’s forum, but I really consider it our forum (meaning “our” in the larger collective sense).


As I said, postwork can be your friend. I don’t do postwork on all my images. I decide on a scene by scene basis, but there are some advantages. Like below:


This first part of this video is a rendered image sequence untouched except for compiling and sound F/X. The second half of the video is the same image sequence run through Adobe Photoshop’s Image Ready with a Poster Edges filter applied. I also tacked on a fly-thru of Dystopia City blocks to which I also batch applied the Poster Edge filter. The toon like effect was much quicker to set up and adjust in Photoshop than doing it in Carrara.


http://www.youtube.com/watch?v=WqkRvyKYDgo&feature=share&list=UU6wB1FKPN4DWpuoVsQY2o8Q

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Posted: 08 February 2013 11:20 PM   [ Ignore ]   [ # 11 ]
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Very cool, indeed! I’m gonna link up some of those vids you did… You rock EP!

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Posted: 09 February 2013 02:32 AM   [ Ignore ]   [ # 12 ]
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Nice to see someone starting to embrace postworking a little more.

Coming from a long personal history of trying and learning any art medium that I could get my hands on, I have never understood the reluctance to use a tool that can be used to make an image (any image, not just a render) better. It’s all about the final look after all.

Anyway, following is a quick technique to get perfect masks out of Carrara for use in postwork. DOF included.

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Posted: 09 February 2013 02:33 AM   [ Ignore ]   [ # 13 ]
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Here’s one of my more recent images.

The first step is actually in the scene preparation, I always keep in mind waht I am going to do in post so I build the scene in groups to accomodate that.

To get a mask,

1. Save your scene, keep it safe.
2. Switch off all the lights
3. Set the backdrop to pure white and remove any other background elements such as atmospheres or HDRIs
4. This is where grouping works for me. Make everything except the figure to mask invisible.
5. Render. You can switch off the image elements that are irrelevant. Maxing the quality settings will still produce a very fast render.

You can see that I have AO switched on here. That’s because I use this method to produce a vey fast, very high quality AO layer at the same time. I’ve mentioned it before but it is often overlooked, AO is produced purely from the geometry and needs no lights at all. (of course you need a lit object to see it but the AO layer will still be the same)

If you look closely at the final mask you can see some colour in the eyes, that’s because anything sitting behind a transparency (not alpha) is rendered and I have a touch of glow in the eyes that will act as its own light source. I could either adjust the shader in Carrara or, in this case, it’s simpler to paint over it when I take it into psp.

This is one example. You can do this for anything when you want to get the perfect edge and the depth pass or object index isn’t working out for you.

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Posted: 09 February 2013 02:55 AM   [ Ignore ]   [ # 14 ]
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One more tip.

For Carrara dynamic hair, the Volume Primitive layer will give a perfect mask in the multiplication part. (the black on white bit)
It’s actually how the hair effect is added anyway and you can use it for your own purposes.

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Posted: 09 February 2013 05:56 AM   [ Ignore ]   [ # 15 ]
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RoguePilot - 09 February 2013 02:55 AM

One more tip.

For Carrara dynamic hair, the Volume Primitive layer will give a perfect mask in the multiplication part. (the black on white bit)
It’s actually how the hair effect is added anyway and you can use it for your own purposes.


So, the volume primitive layer shows the dynamic hair?

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