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otacon
09-10-2005, 10:32 AM
A personal project i did this week, rendered with kray. Comments welcome.

Pavlov
09-10-2005, 11:16 AM
Very good as usual, Otacon.
Wood texture is a bit too strong but it could be a desired effect; the one thing i dislike is exterior, too detail there. It distracts me from observing the room.
Anyway, can you post rendertimes and method ?
It seems Kray users are divided in 2 schools, one likes using custom GI res and use low FG rays number settings with high BD and Oversample values. Other uses Autophotons and lots of FG rays with lower BD/Oversample.
These two gives similiar results, i'd like to hear what method you use.


Bye
Paolo zambrini

otacon
09-10-2005, 11:48 AM
Thanks. Render time was 7 hours 45 min, 1100x1200 res. I still dont completely understand what all the settings do, so im sure it could be faster. The antialiasing alone took about 6 hours. I think im in the group that uses autophotons and lots of fg rays. For this i used 250 fg rays, distance min 5%, distance max 100%, BD 125%, oversample 130%. What does BD and oversample do anyway?

Lighting setup is a big area light outside window, and spotlights in the lamps, one more area light to the left of the wall in front of the camera.

Mebek
09-10-2005, 01:35 PM
If it wasn't for the bedsheet, I'd swear I was looking at a photo. The sheet just looks odd, like it needs more subdivision and wrinkles. I love the green chair though, where can I buy one? :)

Pavlov
09-10-2005, 01:58 PM
Thanks. Render time was 7 hours 45 min, 1100x1200 res. I still dont completely understand what all the settings do, so im sure it could be faster. The antialiasing alone took about 6 hours. I think im in the group that uses autophotons and lots of fg rays. For this i used 250 fg rays, distance min 5%, distance max 100%, BD 125%, oversample 130%. What does BD and oversample do anyway?
Lighting setup is a big area light outside window, and spotlights in the lamps, one more area light to the left of the wall in front of the camera.

Well, i'm still not *that* good at Kray, but here are a few ones:
- use luminous polys instead of areas, they're a lot faster. This way, you'll meet a bug so you wont be able to use "received" photons because luminous poly's photons and direct lights photons would not interact correctly. Anyway, use "emitted" and raise photon number, it adds just a little time but globally you'll get faster.
- 250 are very few rays, but they can be good in some situations.
- distance min 5 % is too little; try to start from 50 % and go down if needed
- BD 125 % is too little, raise it to 300, 500 or even 800. it wont hit rendertime too mch but it's of great help in noise removing (the higher, the less contrast between near points).
- oversample: that's the key factor. starto from 100 and go down, i often use 20% values. Simply put, it will clean your render ;)

In interiors, i usually start form these:
FG 400 Sd 0.3 DistMin 50% DistMax 500% B/D 400 Oversample 50%. Dunno about maxweight, though.
Then, if results are not good i try raising FG rays (it's an equivalent of LW's Ray per Evaluation - the number of rays each sample shoots. In LW, 16*48= 768 = 800 FG rays in Kray).
I keep samples rarefact by using SampleDensity 0.3 or higher.
Then i improve interpolation using both B/D values and low Oversample values (these two behave in a similiar way to LW's Tolerance - they do a totally different thing but you can think this to take the grasp).
Finally, Sample density, DistMin/Max are the way Kray calls LW's Evaluation Spacing. These are brute approximation but i think they'll help some people a bit in understanding Kray.
To complete the parallel with LW's GI engine, it's important to say this: LW fires rays which bounce n time around, Kray dont.
Kray fires photons which bounces n time, and bounce/bleed infos are stored in irradiances. FG calculation happens after this.
Returning to methods...
If i can, i use 400/500 FG rays, 0.2 - 0.3 SampleDensity, Dmin 20-30, Dmax 300-500, B/D 500-800, Oversample 20-40. All referred to Global autophotons mode, btw.
Another thing that will kill rendertimes is saving irradiaces before shootting FG rays; just use Photon evaluation/precomputed to save irradiances, then set Shared GI in LOAD mode and experiment a bit; each time you will load precalculated photon mapping phase.
When you're happy, set Shared GI in BOTH mode and fire rendering. Rendering will finisch, but all Photons and FG data will be save in the GI file, so if you'll need to render the scene again, every calculated info will not be recalculated, but just loaded. This is VERY useful in animations or in multiple shootings. If an area you've already calculated is visible in the second rendering, GI infos will just be loaded, only relfection/refraction will be recalculated. In a single room, you can save big amounts of time if you do multiple views.
I use this trick for baking too: i shoot several views in BOTH mode so i save as may FG rays i can, and when i bake to texture it renders 1000x1000 textures in a matter of minutes.

Try with these settings and tell me if it's faster... i'm curious because you use radically different settings, maybe your ones are better than mine.
PS i apologize, i wrote this message in a hurry so it may result confusing - tell me if it's the case ;)

Bye
Paolo Zambrini

silverlw
09-10-2005, 02:10 PM
First of all, excellent image :thumbsup:

BD stands for "Brightness Density"
If you increase the value the Fgrays will try to group/optimize better depending of the brightness in the picture. High BD values like 800%-2000% is usefull when there is alot of contrast in the image like Strong sunlight coming in through a window and lights up a dark room.

Oversample is an interpolation tool wich goes from 0 to 100%.
At 0% it's like turning of irradiance cache. It will then be very slow but accuracy will be very high. I dont recomend lowering this value since interpolation/render will then be slower. It is almost always a quicker solution to increase Finalgather rays than lowering oversample. Higher numbers than 100% of oversample have no effect at all.

Pavlov
09-10-2005, 02:19 PM
First of all, excellent image :thumbsup:

BD stands for "Brightness Density"
If you increase the value the Fgrays will try to group/optimize better depending of the brightness in the picture. High BD values like 800%-2000% is usefull when there is alot of contrast in the image like Strong sunlight coming in through a window and lights up a dark room.

Oversample is an interpolation tool wich goes from 0 to 100%.
At 0% it's like turning of irradiance cache. It will then be very slow but accuracy will be very high. I dont recomend lowering this value since interpolation/render will then be slower. It is almost always a quicker solution to increase Finalgather rays than lowering oversample. Higher numbers than 100% of oversample have no effect at all.

Generally i noticed that low FG rays (300-400) with low Oversample (20-30%) is faster than high FG rays (ie 700-800) with 60-70 % Oversample. Maybe i've to tweak differently BD and sampling too.. i'll try your suggestions ASAP, i'll have to bake an interior for animation next week.

Paolo

otacon
09-10-2005, 05:36 PM
Thanks for that information, thats definately going to help me figure this out. Ive never been one to read about settings or try to understand how renderers work, i just try things until i get a good final product.
Heres a closeup render i did after i changed some settings around. Im rendering another one now, will post later.

Pavlov
09-10-2005, 06:11 PM
Thanks for that information, thats definately going to help me figure this out. Ive never been one to read about settings or try to understand how renderers work, i just try things until i get a good final product.
Heres a closeup render i did after i changed some settings around. Im rendering another one now, will post later.

sometimes i wonder if you're posting photos instead of renderings..

Paolo

etyrihje
09-10-2005, 06:24 PM
That last close up is so photo real that itīs almost scary,
VERY impressive!

how did you do the chair, is it geometry or texture?

gaushell
09-10-2005, 06:31 PM
Looks great. Background photo perspective is off a bit - look at building in the upper left versus your ceiling on the left.

I agree with the comments on the bed sheet and floor. Otherwise - very very nice.

nthused
09-10-2005, 06:32 PM
Wonderful work, Jason.

otacon
09-10-2005, 06:48 PM
Thanks guys. Background photos are always hard to find, especially ones that match up right. I guess i could do some perspective correction in psp. Im not happy with the bed sheet either. It seems like i always put off the hard stuff for last, and then i never fully finish them. :) The chair is a texture map.

I added the other closeup to my earlier post.

gaushell
09-10-2005, 06:51 PM
Ah come on, you could just build the entire background too :)

great job....

otacon
09-10-2005, 07:40 PM
Actually, when i was searching for a background photo it did cross my mind. ;D

duke
09-10-2005, 08:35 PM
Took a few (thousand) pictures while I was in NY, if you want higher res ones ill upload them for you (they're quarter res now) :)

http://www.dukecg.net/DSC02791_1.JPG

http://www.dukecg.net/DSC04096_1.JPG

http://www.dukecg.net/DSC04117_1.JPG

http://www.dukecg.net/DSC04171_1.JPG

http://www.dukecg.net/DSC04235_1.JPG

http://www.dukecg.net/DSC04237_1.JPG

http://www.dukecg.net/DSC04241_1.JPG

http://www.dukecg.net/DSC04336_1.JPG

Jure
09-11-2005, 10:56 AM
Nice work Jason! Render times are waaay hight though... You must have turned up AA realy high, right?


Generally i noticed that low FG rays (300-400) with low Oversample (20-30%) is faster than high FG rays (ie 700-800) with 60-70 % Oversample. Maybe i've to tweak differently BD and sampling too.. i'll try your suggestions ASAP, i'll have to bake an interior for animation next week.

Paolo

Oversample is acctually very simple to understand. For example turning down oversample by half (ie. 100% to 50%) will double the render time. It will produce twice as much FG samples though - meaning much cleaner render. It has in fact the same effect (on render time and number of samples) as cutting your sample density in half (ie. 0.2 to 0.1) but with one important difference - it produces much cleaner render. I'm not sure why is that but I use that trick all the time - I up my sample density as high as I can (0.2-0.3 is a good start) and turn down oversample (usually between 25-50%).
Oh yea and I manually set GI size (usually 0.5-1m).

ingo
09-12-2005, 01:14 AM
Actually, when i was searching for a background photo it did cross my mind. ;D

Well there is a nifty little program called Photoshop that can do nice perspective transformations to correct existing photos ;) Otherwise nice pictures, can't wait to get my hands on a Mac version of kRay.

Ante
09-14-2005, 05:14 AM
Well there is a nifty little program called Photoshop that can do nice perspective transformations to correct existing photos ;) Otherwise nice pictures, can't wait to get my hands on a Mac version of kRay.


ingo, exactly my thoughts :agree:

greets

ante