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Make Your Most Realistic Renders – Ever!
Posted: 14 July 2013 05:18 PM   [ Ignore ]
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First let me say “Sorry” for a long post, about what is basically a very short message, but I genuinely think it deserves it.

Have you ever wished that your Carrara renders looked more realistic? That despite using all the tricks – IBL, full indirect lighting, sub-surface scattering and the rest, that your renders don’t look REAL? OK, they may be good renders, but they are still clearly renders.

I know that I have felt like that, and maybe like me you looked at other renderers like Luxrender and Octane. I know that when Luxus for Carrara was launched, I jumped at it and have been using it a lot, getting used to how to get the best out of it.

Last week, I tried rendering the same scene, with the same HDRI lighting in both Luxus/Luxrender and Carrara’s native renderer. I was astonished at how different they looked.  It was just a figure – OK, I expected some differences, but this was way different! The shadows in the Carrara render were too dark, the colours were garish, and yet the Luxrender version looked good. How could the same subject with the same lighting look SO different?

And then I tried something which has changed the way I render with Carrara - forever. With ONE simple change, my Carrara render looked very much like the Luxrender!  I tried other subjects, and one after another, they looked so much better, so much more REAL!

I couldn’t quite believe the results I was getting.  My first thought – I’ll be honest here – was “How can I make some money from this?”!  How can I build this into some training or some product?  After all, Carrara users have been crying out for some “magic” which will make their renders look this good.

But the change is something so simple that I can explain it in one sentence. AND (and this is really frustrating!) it has been there in Carrara for YEARS! Surely someone else must know this stuff – but then, wouldn’t everyone know?

So, enough of the hype, I simply decided that the only thing to do was just to tell people, and let everyone make great Realistic renders with Carrara, natively.

All you have to do is – turn on Gamma Correction in render properties and set it to 2.2.

WHAT???!!!! That’s it?

Actually, it doesn’t even have to be 2.2, but that is acknowledged as the best typical value.  What do I mean, typical value, I thought you just said no-one knew this stuff?

Let me explain a little. I previously thought, as you probably thought, that Gamma Correction simply lightened up the image, the same that you can do in postwork with Photoshop or other such applications. And if that is the case, I’d prefer to do it in postwork where I have more interactive control.

So last week, when I used Gamma Correction in Carrara and got such a dramatic quality improvement, I started to do some research. There is a lot on the internet about using something called Linear Workflow in 3D rendering.  In a nutshell, traditional renderers do all their calculations in linear colour-space and then Gamma Correction can be applied to convert that to show properly on a monitor. But when you select colours and use textures in your surfaces, they are already gamma corrected – they already look right on your monitor! If you just apply gamma correction, the colours and textures look washed out.  So they need to have a reverse gamma correction applied, for all materials, then the program does all its calculations, and then the correct gamma is applied to show the resultant image.  You can read more by starting with this link if you are interested (and apologies if my explanation is too simplistic or too garbled):

http://www.vfxwizard.com/tutorials/gamma-correction-for-linear-workflow.html

But essentially what this means is that Carrara and other “traditional” renderers have historically been calculating and displaying results in the “wrong” (ie not matching the real world) colour-space. Which is why renders look like renders, and why we have developed a whole range of techniques and strategies to try to get more realistic results, such as adding more (and more) lights.

Now here is the clever bit – when you turn on Gamma Correction in Carrara, it not only adjusts for your monitor’s colour response, it implements a Linear Workflow solution! Under the hood, it does all that “apply the reverse gamma” stuff, so that your renders come out looking more realistic. How do I know? Well, it’s actually in the Carrara 7 Manual! Yes, it was available years ago. Yes, I have read the manual, probably more times than most as I needed to in order to produce the training videos. It is on Page 812 (of 853) and it says:

“Carrara allows you to “gamma correct” your image so that it matches the luminance of your monitor. This allows you to view much more realistic images. With Global Illumination the gamma correction performs more than to correct the image. It also assures that the textures are correctly taken into account in the lighting calculations. Note that an image that is gamma corrected will tend to be much brighter than one that is not.”

This is ALL it says – and it sounds more like a warning not to use it. It is cryptic at best, but the key phrase is the second one, which leads me to believe that a Linear Workflow is what it is doing. No wonder people didn’t know about it, it should have been shouted from the rooftops – which is now what I am trying to do!

A few things to note. While it works to an extent with any render, it seems to work best with Indirect lighting turned on. And it works terrifically well with HDRI lighting, in fact you should probably not use HDRI lighting without it. I have many HDRIs on my hard drive and some of them used to give pretty poor results – too dark, too bright, overexposed highlights, garish colours,etc. With Gamma Correction turned on, they all look fabulous – and realistic.

For maximum realism, you still need great models, great textures, etc. Also, the core lights in Carrara (and others) such as the bulb and spot lights are not physically correct in that the intensity does not fall off according to an inverse square law as it does in nature – because it looked wrong (with a traditional renderer)!  With Gamma Correction, lights with proper falloff now look right, so for maximum realism, avoid those lights and use something like an object with a glow shader set to 10000%.

The other great thing is – this is still the Carrara renderer that you know and love. You can still use all the same tricks that you have developed over the years – although you may find that you just don’t need to as much. Everything in Carrara is still supported, such as replicators and dynamic hair – although you will find that dynamic hair renders too light so you will need to add a multiplier into the shader to darken them.

Actually, and particularly for existing scenes, you may need to adjust the lighting and shaders, but hey, we are Carrara users so we are well used to doing that!

And just to say that Luxus for Carrara is still very much worth getting.  Luxrender can produce great results where Carrara will struggle, I’m thinking interior lighting particularly.

So what I want you to do, having read all this, is to prove it to yourself. Load up your favourite figure, apply a good shader set, add clothes, pose and hair to suit.  Frame the figure in the camera, an upper body shot can look good.  Turn off the default light. Go into Scene properties and turn off Ambient Light and add an HDRI image into the background, if it is high res, so much the better, but it will work with any. Go to the render page and turn on Gamma Correction and set it to 2.2.  Turn on both GI options – Sky Light and Indirect Light – and ensure that light through transparency (in the GI section) is on. If you have a more powerful machine (or are more patient) you could set Object Accuracy to 0.5 and turn Lighting Quality from Fast to Good or better.

Then hit render and make your most realistic Carrara render ever!

And then share it here.

You will notice that with using just indirect lighting, there are no specular highlights, and the eyes may therefore look a little lifeless. I have some thoughts on this too, but that will have to be a separate post!

Thanks for reading – I hope that this makes you as excited as I have been this last week!

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Posted: 14 July 2013 05:19 PM   [ Ignore ]   [ # 1 ]
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Another example… Just to give you an idea, I think both of these rendered in less than 30 mins.

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Posted: 14 July 2013 05:21 PM   [ Ignore ]   [ # 2 ]
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...and another done today with Dartanbeck’s wonderful Woodlands set, which you should get if you haven’t already! This took less than an hour to render, I compromised a little on the indirect lighting to just use the Ambient Occlusion option for speed.

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Posted: 14 July 2013 05:28 PM   [ Ignore ]   [ # 3 ]
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Leaves me out. I avoid IL like the plague. I use Skylight sometimes. Never both together. Takes w-a-a-a-y to long to render.

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I find it somewhat liberating not to be encumbered by accuracy.

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Posted: 14 July 2013 05:30 PM   [ Ignore ]   [ # 4 ]
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I forgot to add that you’ve posted some nice images, and some good info. for those that care to use full GI.

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I find it somewhat liberating not to be encumbered by accuracy.

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Posted: 14 July 2013 05:38 PM   [ Ignore ]   [ # 5 ]
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Please don’t write it off before you’ve tried it. I’ve had great results in a 15 mins render. Heck, with a little optimisation, I think you could render an animation with this!  And it is WAY quicker than the Luxrender equivalent.

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Posted: 14 July 2013 05:48 PM   [ Ignore ]   [ # 6 ]
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It’s good to know where to set it to begin with, and that it has some use other than being some cryptic setting. I just don’t think it has a use for me, since I don’t use GI or really have a desire to. I may try it out with the standard renderer to see how it does, but if the best results are reserved for GI, then I don’t see much use for it in my personal workflow. I also don’t see a need for Luxrender for myself either, but that’s just for me.

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I find it somewhat liberating not to be encumbered by accuracy.

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Posted: 14 July 2013 05:55 PM   [ Ignore ]   [ # 7 ]
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It is my personal goal to achieve as realistic renders as possible, and I know that many others share this, but equally I accept that others have different aims and that there is art to be found in all forms of rendering.  But Linear Workflow is at the heart of renderers such as Luxrender and Octane and is increasingly being adopted in some form as an option in most high level 3D renderers.  So I would recommend at least trying it out, even if you find it does not fit what you want.  It is worth giving it a whirl, and it may just knock your eyes out in the same way that it has for me. It is almost too easy to produce consistently great results!

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Posted: 14 July 2013 06:13 PM   [ Ignore ]   [ # 8 ]
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Okay, so what about not using HDRI, or is that part of the whole magic? Don’t get me wrong. I’m doing as you’ve asked as we speak. It is taking a quite a bit longer than what I’m used to - being an animation kind of guy. But I’m just wondering about your thoughts of using this idea for more than just HDRI based lighting - say, sunlight and realistic sky?

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Posted: 14 July 2013 06:15 PM   [ Ignore ]   [ # 9 ]
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I’m currently giving it a whirl using the standard renderer. I’ll do one render with it and one without.


I would like to point out that really nice, near photoreal renders can be achieved without GI or Luxrender. I myself have done a couple. wink


No postwork on this one except to paint out some poke through. No levels, gamma or color adjustments period.

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Posted: 14 July 2013 06:17 PM   [ Ignore ]   [ # 10 ]
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Dartanbeck - 14 July 2013 06:13 PM

Okay, so what about not using HDRI, or is that part of the whole magic? Don’t get me wrong. I’m doing as you’ve asked as we speak. It is taking a quite a bit longer than what I’m used to - being an animation kind of guy. But I’m just wondering about your thoughts of using this idea for more than just HDRI based lighting - say, sunlight and realistic sky?

Try it!  If you are using any form of indirect lighting, I think it will yield good results.  If you are using a lightdome so as not to use Indirect Lighting, the results may not be as dramatic but still worth a try. What have you got to lose!

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Posted: 14 July 2013 06:21 PM   [ Ignore ]   [ # 11 ]
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Thanks Phil!

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Posted: 14 July 2013 06:26 PM   [ Ignore ]   [ # 12 ]
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PhilW - 14 July 2013 05:55 PM

It is my personal goal to achieve as realistic renders as possible, and I know that many others share this, but equally I accept that others have different aims and that there is art to be found in all forms of rendering.  But Linear Workflow is at the heart of renderers such as Luxrender and Octane and is increasingly being adopted in some form as an option in most high level 3D renderers.  So I would recommend at least trying it out, even if you find it does not fit what you want.  It is worth giving it a whirl, and it may just knock your eyes out in the same way that it has for me. It is almost too easy to produce consistently great results!

Well there’s that… but I just love having an experiment asked of me - and this really is as simple to set up as you say it is. I started taxing my brain on where I might have an HDR image. Well… you sent at least one with the Advanced Carrara Techniques set, but I opted to try Dimension Theory’s Skies of Terra. His presets, I’ve just discovered, come set up nearly as you’ve instructed, but with a light or two, and the Gamma (in my example) set at 1.6 - I’m using a night scene. So I am just using the HDRI, No lights in the scene, Sunlight on, Gamma 2.2, Full Indirect, AA = Good, Lighting = Good

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Posted: 14 July 2013 09:49 PM   [ Ignore ]   [ # 13 ]
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Thanks PhilW for your wonderful contribution to the Carrara community.

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Posted: 14 July 2013 10:13 PM   [ Ignore ]   [ # 14 ]
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scottidog2 - 14 July 2013 09:49 PM

Thanks PhilW for your wonderful contribution to the Carrara community.

Yes. If I somehow forgot to thank you… Count me in on what Scottidog2 said! Oh… and Phil,
You R O C K !!!

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Posted: 15 July 2013 12:38 AM   [ Ignore ]   [ # 15 ]
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mmmm even ordinary renders one bulb no IBL it is interesting

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