which ones produces more photo realistic images?

They should produce more or less identical images, although I think karma might still have some bugs they're working out. Other than that, Karma does support the new subsurface model that should be more accurate than the older model used by mantra.

What's your definition of “photo-realistic”? Sounds like an oxymoron to me :-) A photo is a subjective representation of what some people consider reality. It depends on everyone involved to define “reality” in an agreeable way to even MEASURE “realistic” and most photos aren't MEANT to be “realistic”. Take a look at the “movie industry”, they aren't exactly about “realistic” representations, if they were, some well-paid actors and actresses would behave rather unacceptable after having seen how they, suddenly, look on the big screen.

That said: Both render engines you mention call themselves “unbiased” (to me there is no “real” unbiased rendering, since you will never REALLY cover all possible photons in a calculation, it's more about “more or less unbiased rendering”, but that's nit-picking). Therefore, in theory, both renderers can give you the same “real” (as in physically-correct-ish) look. Be careful with believing in that, in order to be physically correct, one needs to understand the basics of physics, and so far physicists are still debating that.

In the end, what most people mean by using the phrase “photo-realistic” is the exact opposite of “realistic”: They want to render what they consider “visually pleasing” to their own, subjective, mood-depending preferences. If you hand over a “physically plausible” render to them, they usually say “that looks mediocre”. If you hand over a photoshopped, artistically “improved” render, they'll go out of their way to praise you for the “realism”.

What you want is to LEARN how to use a render engine, any render engine, and create the images you want. What you PROBABLY want is a render engine that is easy to use, offers a lots of tweaks and is fast enough to allow you to experiment. If you really wanted “realistic” (omitting “photo-realistic”), you wouldn't need to experiment, you'd simply hit “go” and be done. That's not going to happen.

Photos are ART. Art isn't done by clicking on a button and going home.


Marc Albrecht

(Note to self: Stop responding to single-post users, it's usually fruitfree.)

(Note to self: Stop responding to single-post users, it's usually fruitfree.)

Nah…don't stop…you give context and pause for thought that I'm sure some people would find of value besides the op'er.

Plus, I can apply my coffee zing towards other matters instead of the time it would take me to write the same/similar.

malbrecht
What's your definition of “photo-realistic”?

I think “photo-realistic” means less biased in the context of renderers.

@malbrecht I think you're complicating the matter to no one's benefit (see jsmack's reply above).
Not that it isn't true what you're saying, but we ought to nevertheless use low-res concepts and ideas when we're casually communicating. Otherwise, the alternatives are to either write a paper or shut up about it.

malbrecht
(Note to self: Stop responding to single-post users, it's usually fruitfree.)

Probably, a better filter to implement is to watch for whether the op has subscribed to his own thread. This has worked best for me.
Cheers!

I think the point that Marc was trying to make is that photorealism is more up to the user skillset than the renderer.

Unreal Engine is a good example of a render engine that cuts all the corners it can, and yet in some cases can deliver very realistic imaging.

To answer the OP – they're both unbiased PBR renderers, but at the moment Karma is limited by its relatively new development cycle and will take more time until it's mature enough to be considered production-ready. If I was limited to one or the other, I would use Karma for look-dev, and then switch to Mantra for the actual final render.

Anonymous user/ess “pickled”, you are, of course, entitled to consider me a waste of time, just like I consider most of your comments the same. Nevertheless, for the protocol, let me state that:

pickled
we ought to nevertheless use low-res concepts and ideas when we're casually communicating.

… you can take your low-res concepts to Facebook and the likes.
In my experience I have lost way too much precious lifetime talking to or with people endorsing their “low-res concepts” and casual communicating. I know some people are really proud of not caring a bleep for anything and refusing to learn while they go along (I worked for “the industry”, you know).
Here, I would have preferred learning about other people's definition of “photo-realism” instead of being told to shut up if I don't write a paper about it.


Marc Albrecht

peterclark
which ones produces more photo realistic images?

I'm not keeping count, but I'd guess that so far Mantra has produced more photo realistic images than Karma

@malbrecht
I didn't say that I find your comments useless nor do I think I implied that. In fact I don't think I showed any sign of hostility. You've let our previous interaction influence how you perceive my reply. That's fine, I'll keep my distance from now on.