Rectangular lights create noisy reflections??

[stevebo]

Hey guys!

I've always mainly been working with exterior renderings. However, I've been needing to do a few interior ones lately. I've started using rectangular lights to light my scene, but I get these kinda noisy elements in the image, say on the leather chair and on the wood. Also the walls have these blotches. I'm using the Physical camera. The duvets on the bed (thanks ande) is a simple diffuse grey colour, but it still seems to be reflecting a fair bit!

Many thanks in advance!



Steve

[stevebo]

Re: Rectangular lights create noisy reflections??

Just did another render and I just noticed that the reflection in the mirror has worked for everything but the wood floor!

[davidmurphy991]

Re: Rectangular lights create noisy reflections??

Steve,

Reverse the face of your wooden floor that should sort out your reflection issues.......

zzzSPUDzzz

[dalomar_cg]

Re: Rectangular lights create noisy reflections??

The leather chair and the wood simply need more subdivisions. The splotchiness will need a better IR solution, so you should increase the hemispheric subdivisions. The default value of 50 won't be enough for interiors

[stevebo]

Re: Rectangular lights create noisy reflections??

Thanks guys!

I'll have a play around with it and upload once I sort it out!

[Jackson_cg]

Re: Rectangular lights create noisy reflections??

Could the splotchiness not also be a result of those uplighters in the coving just being too bright for the scene? They're burned out pretty badly around the edge of the ceiling.

As always I defer to Dalomar's expert opinion, but I've got to say that I often use Hsph. Subdivs of 50 and Samples of 40 for interiors without splotchiness problems, though of course some scenes require higher settings. Is your DMC Adaptive Amount set to 0.85?

[dalomar_cg]

Re: Rectangular lights create noisy reflections??

Having your samples at 40 will blur the GI solution. This may be why a lower subDiv value works out as the samples may be blurring the splotchiness.

[stevebo]

Re: Rectangular lights create noisy reflections??

Thanks for the tips guys! It's looking better already! Just need a bit more tweaking!

I have boosted up the subdivisions of the materials lots though. Like up to the thousands.

I actually didn't increase the samples of the IR map, so I'll try it with that.

[Jackson_cg]

Re: Rectangular lights create noisy reflections??

Having your samples at 40 will blur the GI solution. This may be why a lower subDiv value works out as the samples may be blurring the splotchiness.

Yep, but I thought you once said that increasing subdivs should be accompanied with increased samples?

SteveBo,

If, by "subdivisions of the materials" you mean the subdivisions controlling the quality of glossiness, anisotropy, etc, then you are WAAAAY out in numerical terms- the most I have ever used was 64 subdivs for a leather material. High subdivs (by which I mean over 32) on reflective materials come at an extremely high render time cost. Setting them even in the hundreds would probably give no noticable improvement and would multiply your render time several times over.

In general I works in multiples of 6 (I don't know why, it's just a habit I've gotten into), for some materials subdivs of as low as 6 are actually ok, for most 12 is low quality, 24 is ok, 36 is good and 72 is excellent. Perhaps other users regularly push them up further, but working on my 3 year old Centrino Duo laptop I always try to keep render times as short as possible.

[stevebo]

Re: Rectangular lights create noisy reflections??

Jackson,

Thanks a lot for your help. Here I've uploaded my model, which should have all my material and scene settings saved. If you have the time, could you take a look at what I'm doing wrong? And sorry for the messy model... 2 years of using Sketchup and still not a competent user haha.

It also seems like sunlight is entering the room but I've bumped the sunlight all the way down. Maybe I should just turn it off completely?

Sketchup file

[dalomar_cg]

Re: Rectangular lights create noisy reflections??

Yep, but I thought you once said that increasing subdivs should be accompanied with increased samples?

I don't think I ever said they should be, but maybe I said they could be...you've got to be careful with that samples setting because that can make a good solution loose its detail, and that's a shame if you're throwing 150 subdivisions at it. With more subdivisions you may be able to get away with a few more because, in general, those samples that are taken will be more accurate, but if you keep taking more and more, their influence will still be less and less. Personally if I'm taking 150+ subdivs, then maybe I bump it 30, but its not the first setting I'm looking to adjust within IR.

[Jackson_cg]

Re: Rectangular lights create noisy reflections??

Ahh, ok... the highest I ever set the Samples to is 60, but I guess I should start ramping that right down. Mind you, it does get rid of the splotchiness LOL.

Steve, I donwloaded your model, I'll post it back when I've messed around with it.

[stevebo]

Re: Rectangular lights create noisy reflections??

Thanks Jackson!

You're a legend . And no, I don't use that word very often.

[stevebo]

Re: Rectangular lights create noisy reflections??

Any update?? Sorry for pestering but it's just that it's a near deadline for the project and I would like to have a good render.

[Jackson_cg]

Re: Rectangular lights create noisy reflections??

Hmmm....... I don't mind helping folks out, but I didn't realise that I was voluntarily helping you keep a deadline which you are being paid for. >

6 years ago I would liked to "have a good render", but I just put my head down, buried my head in the manual, read as much as I could on forums, asked as many questions as I could and practiced, practiced, practiced and even then I only started offering my services professionally just over a year ago.

In spite of this, some general tips (apart from everything written in posts above):

1 ) Keep all faces with normals facing outward- your model had many facing backwards.

2 ) Use sensible material names- your model had about 5 white materials called Color 0002, Color 0004, Color 0010, etc. "Plaster", "Wood White", "Porcelain", etc is much easier to keep track of (and for exporting).

3 ) Don't use any materials which have 255,255,255 white diffuse colour- it doesn't exist in the real world anyway and it causes horrible artifacts.

4 ) Learn how texture scaling/UV mapping in SU works before you start messing around with VRay's texture scaling. There's no point having a wood texture scaled at "1" in the SU viewport, but with a scale of "0.0001" in VRay. It completely screws up bump, reflection, displacement maps, etc.

5 ) Polycrunch imported organic meshes- those duvet covers were way too high-poly for such a simple model.

6 ) Don't make materials reflective unless they really need to be (i.e. wood)- it's a massive render time killer and often doesn't contribute much to the image.

7 ) I can't think of any reason to have Hsph.Subdivs at 500! 100 is max for most purposes.

8 ) If you just want lights/luminaires for effect rather than actually for providing lighting to the scene just use emitter materials (like I did in the uplit coving below).

9 ) Use large rectangular lights to provide interior fill lighting- in the image below I placed an enormous invisible horizontal VRay Rectangular Light right in the middle of the room, scaled almost to the walls. It provides a general warm light to the room, but very efficiently and without very noticable shadows. Of course the ceiling is extremely burnt, but I wasn't going to spend any time perfecting this render anyway.

I was going to post the model back with my changes, but I'm not in the business of giving away vismats, visopts and SU modelling which have taken me years to learn and develop just so someone else can be paid for it. The tips above and in many of the VfSU General Forum threads plus the freely downloadable visopts and vismats on this site should be more than sufficient to get your renders up to scratch so you can start hitting deadlines.