Keyshot vs other Renderers?

[Kinetic99]

Hello and thanks for your time,
I've been using KS for a while now and it seems to be pretty good. Its fast rendering times still perplex me however. How does KS render so fast compared to other rendering software like Mental Ray or Vray using very close and comparable scenes, settings and res?
Does KS skip over something where the other renderers handle better? therefore the other renderers would expect longer rendering times?
What are KS limitations, if there are any?

[DriesV]

What about that KeyShot is just better?

Dries

[Kinetic99]

Ok what's better about it and why?

[DriesV]

One area that's definitely better is caustics and dispersion. In my opinion.

Dries

[Kinetic99]

Better caustics then Mental Ray?
I wasn't even going there but at least I had a good laugh to start this post off
I am mainly trying to understand how does it produce seemingly fast render times for relatively the same quality or image compared to other renderers.

If I render a ring at 2000x2000 in KS, it can take about 10 min, whereas in MR or VR it can take up to 2-3 hours. Am I just increasing the sampling or raytracing parameteres in KS?

[DriesV]

Dispersed caustics are definitely better than MR...
In KeyShot they are physically accurate. Often you have to resort to fake solutions to get the same thing in MR/Vray.

Can you do this in MR/Vray without cheating?
These are straight KeyShot renderings. No fake refraction gradients, no color band settings for dispersion...just straight optical simulation in KeyShot.

Dries

[Kinetic99]

I've never tried or ever needed to break down light beams into the colour spectrum in and rendering application and I'm not sure if MR or VR can do it to the level seen in the image you provided but what you showed me is light refraction and not necessarily refractive caustics.
VR and MR can do real caustics in any appliocation or scene, through glass, water, underwater scenes, reflective scenes, etc.
Also, the version of KS that I am using is a plugin to a CAD software in which I believe it is a dumbed down version. I think it has limitations so I dont even think I would be able to produce that level of light refraction that you showed me.

Anyways, any idea about the render times question? Or do you think render times are just as long as VR and MR and I have not delved deep enough into it?

[DriesV]

...
what you showed me is light refraction and not necessarily refractive caustics.
...

Well... these are most definitely refractive and reflective caustics, taken to extremes.
In fact, most renderers like Vray or MR are quite poor at these.

As for rendering speed and quality, then I think global illumination results of the KeyShot realtime renderer (realtime window and max. time/samples rendering) are very good (fast & accurate). I don't think KeyShot skips anything physics-wise. How could it be physically accurate if it did?
On another note, perceived rendering speed will vary greatly with the kind of scene. For product shots KeyShot is by far the fastest renderer (in my experience). For interior shots, Vray can give way faster and better results, but that is mostly due to Vray being a lot more configurable (thus being more complex). Vray can be finetuned for very different scene types, whereas KeyShot is currently optimized for product shots.

Dries