Rectangular lights create noisy reflections??

[stevebo]

Re: Rectangular lights create noisy reflections??

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Okay. So I've done a bit more. Still not satisfied with the results though. I've turned down the subdivs to the regions of 4-16 to the materials and turned off reflections in some of the materials such as the wood.

I think the problem with using a rectangular light in the middle of the room is that it casts a small shadow onto the walls because of the edge of the rectangular light. Any particular way around this? I also kept no decay on because turning it off made me have to boost up the rectangular light's multiplier quite a bit.

This time it took just a little over an hour to render. It should still be able to go down a fair bit right?? I'm using an Intel Pentium Dual-Core T4200 @2.00GHz with 3.00GB RAM (even though only 2 is used?).

I also tried adjusting the camera a bit to get that horizontal to work and the verticals to be.. well.. vertical but I think the rooms a bit too small to lower the FOV any more. (I'll be honest, I didn't quite understand what you meant about rotating the whole camera thing but then I had a dream last night where I was taking photographs and was trying to find that horizontal then I sort of understood )

And yes... there is a pile of gold in the bathroom. My clients are quite the rich fellows! ;D

Thanks!!

[Jackson_cg]

Re: Rectangular lights create noisy reflections??

Damn, sorry Steve, the shadow on the walls is my fault. I just noticed (and corrected) a typo in my last post- it should have read "Ignore Light Normals" box should be ticked, not unticked as I wrote, sorry about that. :-[

Judging by the shadows on the walls your rectangular light might actually be too big now, trying bring it in about 500mm (1½ft) from the walls. Like I said you want it to light the room very evenly without actually casting obvious light or shadows onto surfaces. It can be a tricky balance.

I notice one thing very odd in your render- the reflections on the leather sofa are grey- it looks like you've done something weird to the fresnel reflection, like added a grey filter or something? Great for pearlescent car paint, but it looks stange here.

Re: parallel verticals- you're almost there, just lower the camera position about 150 mm/6 inches and then rotate it slightly upwards until all the vertical edges in the room become vertical on your actual screen. If you switch anti-aliasing off in SU you can see exactly when they become vertical as they'll display as perfect vertical lines rather than jagged ones. If you still feel you're not seeing enough floor in front of the camera just lower the camera position again. (As an FYI for anyone new to SU, you do this by selecting the "walkthru" tool in SU (the little footprints) and then type in a new camera height, or hold down Shift and move the mouse downwards)

Re: render times, you're on a very similar, but faster machine than I am and I'm pretty sure I could render this out in well under an hour (at this resolution anyway- is the image you've embedded here full res?).

I covered a lot of this before, but I'll put it in list form so others can get the info fest.

Things that make renders slow:

a ) Using DMC as secondary engine. I never use DMC... never. I've had red-in-the-face arguments with colleagues (even an ex-boss, though that's not why he's my ex-boss LOL) about this issue. I'm certainly not saying that you should never use DMC, but personally I haven't found a project yet, interior, exterior, day or night which couldn't be rendered perfectly well using Irradiance Map as Primary and Light Cache as Secondary in a fraction of the time of just DMC. To prove a point I once ran two large identical daylit interior renders overnight and showed them to my stubborn boss (who absolutely refuses to use anything other than DMC) the following morning and asked him what he thought of the them without telling him which was which- he absolutely couldn't tell which was the DMC rendered one. In fact the only visible difference between the two images was that the DMC one was slightly brighter overall. BTW, the DMC render took about 10 hours, the IM + LC one took less than 2 hours. Faced with incontrovertable evidence, did he back down? Did he hell! > He was just p*ssed off that I could render an identical image 3 times faster on my Core Duo laptop than he could on his Quad-Core Desktop by understanding VRay better. LOL

b ) Too high, or incorrect settings for your engines. Dalomar may jump in here to warn of my gross generalisations (and my far-from-complete understanding of many of VRay's finer workings), but for final renders I set an IM min and max of -3 and 0 respectively, Hsph. subdivs 100, Samples 20 or 30 and set the LC subdivs according to the size of the render - for 1400 x 800 pixels I use 1100 subdivs. This will get you as good results as you're likely to require and in the minimum of time.

c ) Loads of non-glossy reflective materials, and having too high subdivs on them. Re: subdivs, start low (12), run a quick test render and work your way up until you're happy- sometimes as low as 24 will suffice for certain materials (esp those with lots of diffuse detail), sometimes you've got to go up to 64 and maybe even beyond for chrome, etc.

d ) Displacement. It can look great, but it's a time-killer. It's way overused IMO, especially for grass where post-processing in Photoshop can put a beautiful freshly mown lawn in a foreground in a couple of minutes compared to rendering plastic-looking displacement grass for hours. Like I say it can look great, but it still takes post-processing to make it rock, so it's not always worth it. For a short pile rug like you appear to have in your model you can probably just use a tiny scaled noise bump map combined with modelling very slightly uneven edges to the rug in SU. It might not look good enough, but it's worth a try as it'll cut your render time by probably at least half.

If you PM me your model (Sprend is a good, easy free file sending service) I can take another look and see if there's something obvious that's resulting in slow renderig times. It could well be the displacement

[stevebo]

Re: Rectangular lights create noisy reflections??

Hey Jackson.

So here's an update.

I'm still getting the shadow from the lights with or without the "Ignore Light Normals" box ticked. Maybe I'm actually doing something wrong with the lights itself?

Time wise, I got it down to around an hour or so, so that's good .

I have no idea what's wrong with the leather? I downloaded the material from I think the vray package thing, but I don't quite remember. I played around with it, but I think it may be the bump map, not the fresnel? (What does Fresnel actually mean by the way?)

I think I've got the parallel verticals pretty much there now! Thanks! ;-D






For some reason, I'm having problems with your PM page, so here's the model: http://files.getdropbox.com/u/445006...20room%203.skp (I prefer using GetDropbox )

[Jackson_cg]

Re: Rectangular lights create noisy reflections??

Steve,

Verticals are looking great- notice how much larger the room looks now without changing the Field of View/Focal Length? Should put a smile on your client's face!

The fresnel effect describes the way that many materials (wood, leather, plastic, gloss paint, etc) have a varying level of reflectivity depending on the angle from which the surface is viewed. Usually, the more acute the angle (i.e. the closer your eye is to the surface) the higher the reflectivity. The lower the fresnel value in the VRay Material Editor the stronger the effect- in other words the reflectivity will drop off very quickly as your eye moves up from the surface. The higher the value, the weaker the effect. When the fresnel value gets really high (say above 5), it will appear as though there is no fresnel effect i.e. the material will reflect pretty much equally from all angles like chrome does.

I took a look at your skp file and had a little dig around, but I'm really pushed for time just now, so some quick notes:

1 ) Re: the horizontal shadows on the walls, try making the rectangular light(s) smaller and moving them in from the walls. Alternatively scrap the horiz rect lights and try using a standard vertical rect light behind the camera and increase your other rectangular light multipliers so they're contributing more light to the scene. There's more than one way to skin a cat!

2 ) I think the weird grey effect on the leather was caused by the Highlight Glossiness being lower than 1. I must admit I don't really understand the point of the Highlight Glossiness parameter. I know it's supposed to be used to create fake highlights on reflective objects (i.e. to simulate highlights as though there were omni lights in the scene even if there aren't), but in my experience in arch renders it just looks weird so I always leave it at 1. If your Reflection Glossiness is set below 1, it'll make the material reflect any actual light sources in the scene in a very realistic way anyway, so you can just leave Highlight Glossiness at Default 1.

Hope this helps,
Jackson

[stevebo]

Re: Rectangular lights create noisy reflections??

It puts a bigger smile on my face .

Thanks for explaining the fresnel effect . I'll have a play around with different fresnel effects when I have time!

There's more than one way to skin a cat!

I know of five . Only tried three though :P.

Thanks for all the help mate! I will be playing around with it further. Seriously, with all the tips in the topic, you could probably write a good few chapters in a Vray manual!

Steve

[stevebo]

Re: Rectangular lights create noisy reflections??

Feeling happier about the results now! Although it did take a bit longer to render. I think I can cut that down with a bit more experimentation .

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[Jackson_cg]

Re: Rectangular lights create noisy reflections??

Looking good Steve!

You're probably sick of my comments now, but I'd turn down the multiplier on the fill light behind the camera and turn up the multipliers on the rect lights in the actual luminaires in your model. At the moment the fill light is completely overwhelming your scene (though you did a good job of correcting it in PP)- it looks like a photo taken at high ISO with a compact camera where most of the light is from a single flash rather than using long exposure to let the scene light itself. It'll also correct the beds in the foreground being burned as they are at the moment.

Did you set the Highlight Glossiness of the armchair to 1? It still has that weird reflection on it. Come to think of it, it could be a bug caused by using too high softening applied to the sofa in SU. Anything above 45° can cause very weird render effects, so try reducing it and ideally find a "softer" armchair model.

I know I said the duvets were very high-poly for this model, but what happened to them? I can poly-crunch them for you if you like, the image really needs sheets on the beds!

This is more a design issue than render related- what's with the coving and lighting going over the built-in wardrobe? Personally I think it would look better if the wardrobe went all the way up to the ceiling and the coving went around it and also from a practical point of view- it would be much easier to change the light tubes.

[stevebo]

Re: Rectangular lights create noisy reflections??

Nah... Not sick of them just yet . Give it a few more comments and maybe .

I'll try again with a lower multiplier on the fill light!

I did set the armchair highlight glossiness to 1. I kinda made that armchair myself... so maybe it'll be better to use one from the warehouse. I'm not familiar with modelling curvy and more organic models.

I tried polycrunching them using that plugin Thomas posted, but it kinda crashed my machine. I'll give it another shot though. I want to try myself before anything so I that I can get first hand experience . The client's already seen the model, so now it's just for my own satisfaction .

Thanks for the tip on the wardrobe . I'll change that. By the way... are you an architect Jackson?

[Jackson_cg]

Re: Rectangular lights create noisy reflections??

Steve,

Re: the armchair- yep probably better to find another armchair on 3D warehouse which already has softer, more rounded corners so you can use a lower softening setting.

Re: Polycrunching, my quote from above:

A much better option is "Meshlab" http://meshlab.sourceforge.net/; a fantastic open-source free program which import and exports most of the common 3d modelling formats and has an excellent poly-reducing function. It does a thousand other things too (900 of which I don't understand ), but the one I use 95% of the time is:

Filters>Remeshing, Reconstruction and Simplification>Quadric Edge Collapse Decimation

Just set the target number of polys (usually takes a few trials before you'll be happy) and if it's important that the edges of the mesh remain exactly as they were before polycrunching (e.g. if they have to "fit" to some other geometry in your SU model) tick "Preserve Boundary of the mesh".

It sounds complicated, but if you follow the instructions above it's actually very easy to use and does an amazing job of reducing polys and has never crashed on me yet.

Yep, I'm an architect trained in Britain and Sweden (where I now live). Architecture is still my first passion, modelling and rendering a close second!

[stevebo]

Re: Rectangular lights create noisy reflections??

Excellent. I'll be trying it out .

I'm currently in my second year of studying architecture at Bath University in England .

[stevebo]

Re: Rectangular lights create noisy reflections??

Finally got round to doing this! ;D

Thanks for all your help Jackson! Obviously still much room for improvement, but I'm definitely far more satisfied with the results now. Only thing I haven't done is the polycrunching. I have tried it and it works. I just don't have Sketchup Pro to export the file to another filetype on this computer.

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A little bit of bleaching of the spotlights on the second image. I think the lighting from the en-suite works better this time