quasi monte carlo setting

[flipside]

Hi,

With old vray version, if you used IR map for first bounces and qmc for second bounces, was the subdivs of the qmc tied to the subdivs of the IR map settings?

I also have high rendertimes with old scenes, is this only due to this qmc setting? Was it maybe in the old version always very low?

It would be nice to have some info on the differences between the old and new vray, how they compare. For example also second bounces multiplier is now default 1. This used to be 0.5 and if you used 1 you had very saturated GI. Why is this now default 1, and should you put it back to 0.5 is you want to rerender an older scene?

Thanks,

flipside

[tom schuelke]

Hi Flipside.

so far as we have encountered with the internals, most important are at first the new standart Qmc settings.

first, what was before in 1.09 15, now should be 8 if i am not wrong, and it does the same thing with 8. so if your old scene gets loaded, take a look and lower this setting.

secound, glossy standart is also lowered to 8 which should be the new standart. this also would be a time eater. so take care that your glossy material settings get the new setting. (i think als this settings will stay the old values when loaded in the internal, so you have to lower them manualy).

vlado some time ago posted, that the most physicaly accurate settings (available for vray), means, a multiplier of 1 for the first lightbounce and also 1 for the secoundary bounces, if you try to get accurate diffuse light bouncing. If you do so, vray will calculate accurate diffuse light distribution taking in acount the rgb values of your objects (which in my opinion still isnt perfect accurate, though).
I think they have switched this standart values to 1, because, the physical most exact settings are a good starting point for renderings.

what also changed is the method of antialiasing ( the middle method , don´t have the exact name here at home). Here, the antialiasing is bound also to your qmc settings. Maybe Geddart could explain this later, because he chatted a while ago with vlado, and was very exited about the reason why. Only thing i know here, take care of your qmc settings here, because they directly influence these antialiasing method.

what changed most at last in my opinion is the workflow in interiors, due to lightmap as new method. While this is totaly new to users that take first time their hand on the internal, and there isnt anything comparable in 1.09, you all should try this out.

lightmap can be used at first for very very impressive fast lightsetups in interiors. Like with photonmapping, you switch first and also secoundary bounces to lightmap, and get very fast lightsolutions for previews. for this maybe lower the settings from 1000 to 300. also for previews you might turn out raytracing in the global switches. (here i could also wish two buttons not only for raytracing, but for reflections and also refractions, because right now you also make your windows black, so no light can come in anymore).

for final images, use lightmap with settings about 1500 to 2000 in very high settings. the quality depends on the amount of rays, and how big your "lightplaques", as Geddart and me have started to call them, are. the more lightrays hit the area of a lightplaque, the better the solution is.
there are two methods of blurring the lightmap and their "lightplaques", standart is the secound method, that blurres the lightmap at rendertime when the final image is rendered. So this method only works, when lightmap is the used method for first and also secoundary bounces. When using lightmap for secoundary bounces and any other method for first bounces you should use the other blurring method. ( the first method, which is gray in standart settings), this method blurres the solution before the next pass, (for example i-map) is calculated, and so is the best solution if you use l-map only for secoundary passes.

in flightthroughs, switch to flightthroug method and also to world units for the lightplaques.

well, maybe we should write a little tutorial for this, but right now i realy don´t have the time. Something like this should be also in the manual i think.

hope this helps a little bit.

Tom

[flipside]

Thanks for your reply man!

Some new questions:

-I don't understand what you're trying to say about 15 and 8 etc... You're only talking about new default settings no? I mean, value 15 doesn't equal 8 in the new vray or something like that?

-if you use L-map for first bounce, and L-map for second, this is the same as L-map only for first bounce and nothing in second (in my small tests)

-L-map seems fast but it seems you cannot get detailed GI with it (need to test more probabely)

I'll get back to this thread later tonight!

bye,

flipside

[tom schuelke]

Hi flipside

sorry for my bad english. the other problem, is, i havn´t the new version here at home, so i try to recal it from the head

hmm, ok evrywhere when you hade any standartsettings with 15, so for example in the qmc sammpler menue, you did have in earlier versions the standartsettings of

amount 0,85
noise threshold 0,005
and
min samples, 15. the new standart settings now are:

0,85
0,005 and
8 instead of 15.

this doesn´t get changed when you load an old scene, so you have to look at your qmc settings, when you load an old scene.

same with glossy materials. in 1.09 the standart settings for glossys are (here i was wrong i think)
50 subdevisions.

well the new version seems to do the same job with only "8 subdevisions".
I think it realy eaquals the old value of 50. same in qmc.

and also this value comes in in the old way when you load an old scene.
so any scene with glossys, you have to go through your glossy settings and have to try out, if a lowered valu of 8 does do the job as well as a higher value. I think this is the problem, why old scenes are rendered slow at first. but i think some more tests would be good, to be sure about this.

the thing with lightmap, i didn´t try out lightmap for first bounce only. well, but this sounds correct to me, due to lightmap calculates lightbounces to its end, when all energy is distributed, so no secoundary pass should be nesscesair.

lightmap like photonmap usualy is good for fast prerenderings. it isn´t thoungt as a final method usualy. But compared with photonmap, sometimes you can do that if you want with high blurry values.
At last you get much better details, when you lower the setting from 0.02 to for example 0.005 which gives you 4 times smaler lightplaques. but this way you also have to make much more lightrays. ( 1000 means 1000000 lightrays in one immage, 2000 means 2000x2000 = 4000000 lightrays). so you can get more details at the cost of higher rendertimes.

Tom

[Da_elf]

its a little thing that when you load old scenes. the QMC comes up as 50 subdiv. DEFINATELY!!!! lower that hehe. when you create a scene from scratch i think default for QMC on secondary bounce is something like 8. so just lower it to 8 and all should be fine. ive gone as low as 4 some times. on exteriors mainly

[flipside]

I don't think the glossies value of 8 equals the old 50. 50 was just way too high as a default value, so they lowered it to 8 because that's more than enough in most cases.