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A quick test of VRay scene rendered in KRay 2.62. WIP

Nice!
Can you share scene? ...of course ONLY for testing not for commercial purposes.
If not, can be only scene without textures.

Dear Janusz,

Yes we need an up-to-date scene (or 2 with a exterior one) on Kray 2.62, while we'are waiting the release of Kray 3.
Something that would sum-up your latest "trends' in terms of light set-up, rendering settings, and surfaces.

Thank you. And +1 to cruisermori to send this scene if possible.

Nice! Can't wait to see what Janusz does with this in K3!

I will post also render from KRay 3. So far I'm not able to reach good quality.
First render with materials is from VRay (just for information). My plan is to try to reach a similar result with KRay.
You can buy this scene at Evermotion - Archinterior vol.35.

brownie wrote:Dear Janusz,

Yes we need an up-to-date scene (or 2 with a exterior one) on Kray 2.62, while we'are waiting the release of Kray 3.
Something that would sum-up your latest "trends' in terms of light set-up, rendering settings, and surfaces.

Thank you. And +1 to cruisermori to send this scene if possible.

That would be a great idea I agree.

Funny that it's a scene from Evermotion: a company that came by to show their ArchViz portfolio had this interior in their portfolio - and it was by far the best render!

K3 render - 1h16min
Still a lot of noise.

cruisermori wrote:K3 render - 1h16min
Still a lot of noise.

You need Light Portals in windows - that's why is long and this is normal. Photons from outside (only background light sources are the most technical difficult to render - photons has really huge problems to feel up scene inside - that's why you see noise. Noise means NO INFORMATION or NOT ENOUGH INFORMATION)
We do not have Light Portals becasue....we do not need
K3 has perfect Photon Map - there is nothing on the market even close to compare with quality PM in K3.

Simple add to scene LEM in places where are windows.


Even in Path tracing engines they use Light Portals to speed up render or reduce noise.

On Dual Xeon (you used perhaps i5/i7 CPU also) this scene with this resolution should be in 2-5 min in override mode.

I'm confused Janusz. First you say we don't have light portal because we don't need them, and then you say to put LEM rectangles in the windows, which are, basically, a very limited version of light portals, since most light portals actually implement the direction of direct sunlight and skydome blueish color.

Sooooo... How do we get good PhySky interior lighting with the efficiency of light portals in K3?

Always you need support light in windows - although you have real time tone map with clip bright/dark regions. But this has a little no sense becasue if you do not use support light (light portal or LEM) you get a lot noise inside.

Why in other software they use only background light? Simple: becasue they need speed up render (is freaking noise of course) but the have choice: use one fill light ans Sun (so only two light sources) or add extra lights in windows and extend render.
For K3 is doesn't matter 2 lights or 20: almost same speed.
Is enough to see Corona or Fstrom renders: simple rooms with small amount light sources. of course they are great Engines but ...very slow.
Actually Corona is really fast but I see also errors in GI there (G. info: "approximately Path tracing Interpolations...or something that)
Corona has good features: real time tone map, real time post process, shader system.


Light Portals has only one purposes: to collect photons from one side and shoot them to other.
Without them Photon map is highly unorganized. Unorganized Photon map create noise (not enough information for next sampling stage).
They shoot "parallel" photons to other side (in our case interior). Light Portals helps poor written Engine Renders to handle this mess what is inside interiors lighting by external background lights. Details how Light Portals works - mail to G.

With good PM solution (K3) you do not need them - easy life: copy/paste windows glass create LEM surface and hide them. target of that is support light from outside.
People make huge mistake using Area Light outside interiors, just behind windows - IT HAS NO SENSE.

You can put Area Light instead of LEM panels but how it is uncomfortable to do it! and effect is almost the same.
Of course light is a bit artificial becasue this ADD color instead transport Physical gradient to inside. But when they mix together (bluish LEM and Physky) it is slightly noticeable.

LEM lights in K3 has Area Light behavior but speed of luminosity!. This is very unique.

Light portals are trouble makers - crashes, long calculations, not enough collected photons generally. Personally I do not like them.

Simply create LEM (200-500% luminosity) , hide them , put bluish color (use Kelvin LW scale). Easy to control, ultra fast render, no noise, no "nuclear" light from outside (after that we do not need bend tone map too much), no need Area Lights (physical lights are raytracing renders lights - always long to calculate)

If you need perfect Light in interior - use Area light instead LEM. K3 has new engine for them: simple perfection.
Is no problem for single room with 1-3 windows. You will get really fantastic and realistic shadows. But K3 LEM are not so far from them.

Thank you Janusz for help. I forgot to switch on LEM panels in the windows. New render took about 48 minutes. Much better result.

Okay, I got it! Thank you for the very detailed and clear explanation Janusz!

Generally: Background light source means troubles.
It is really difficult to make less noise from that light source. G. optimized a lot in K3 Core this part of engine and still he must do more.

Also There is so many false feelings according HDRi: HDRi gives me good light and good reflection. Is not true.

First of all HDRi is very unstable light source which produce a lot errors in photon map. It gives a lot "hot photons" which contain big spectrum of light power. Is enough when one "broken" pixel (or even broken HDRi map) fire photon into interior - it will create mess as hell in photon map like crazy bouncing ball in box. After that engine has problem to balance it and when comes sampling phase it produce noise or horrible bad colors.

Second HDRi has "too sharp" gradient power light: for example when ground meets sky on the horizon. There are pixels with big spectrum of light power- this also produce errors.I do not talk about photons comes from HDRi Sun - this is the worst solution because this is not real physical light.

Third: reflection from HDRi looks good because....is very strong as light source with high contrast. That`s why reflection is more "rich". It doesn't mean this is correct effect.

Hdri can also produce "hot pixels" - very strong random white pixels in render. Coders try make even special de-noise filter for them.

There are some Engines which has special features for HDRi: like replacing Sun with real physical light or blurring image HDRi image before shooting photons, etc.
I suggest use Physky2 from K3 which was created from the newest university researching for best simulation of exterior lighting. Also gradient background can be use is somebody wants different color feelings in render.

And what many beginners in ArchViz seem to forget: when professional interior photos are taken for glossy magazines, they also place bounce cards and lightboxes allover the places outside the frame - exterior lighting just doesn't feel very pleasant in most interiors as a single light source, so even if your render would be technically perfect, realistic and noise free you would probably need to add extra light sources.