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imashination

3D Fluff freebie, halve your render time

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Time for something new, cut your render times in half with a click

 

 

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That's interesting. I'd always assumed that if people were using reflection layers like Beckmann etc they should use the specular controls in that, and delete the standard specular that is only there by default for previous version compatibility. I notice you didn't do that, so was wondering if you would get your render saving by removing that without having to disable it in the lights ?

 

Also, for general information we should probably add that with Physical Render you can go one stage further than this and get an even greater render saving (in some circumstances) if you bin the colour channel as well, and do that with a reflection base layer instead.

 

CBR

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By deleting the default specular and changing the specular strength in any reflection to zero will give the same time savings with the added benefit of still having the specular on any objects that might show a great visual difference from having specular on them.

 

What is interesting with this scene is the added render time that comes from having so many spot lights.  Trying the scene with other render engines I found that Cycles has a problem with a ton of spot lights.  Vray and Redshift seem to go through it pretty fast.  As a side note I was testing some scenes with the latest version of vray for c4d and it seems they did some major improvements over a few years ago.  It seems easier to get flicker free in animations and it renders fast.  Redshift is a beast like always.

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2 hours ago, Fastbee said:

By deleting the default specular and changing the specular strength in any reflection to zero will give the same time savings with the added benefit of still having the specular on any objects that might show a great visual difference from having specular on them.

But we are still losing the specular from the material, which is arguably not a good idea, as some specular is unquestionably part of realistic lighting. We definitely shouldn't have it twice, but just wondering if we can get that render saving and still have, say 20% specular as part of a Beckmann layer for example...

 

CBR

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15 hours ago, Cerbera said:

But we are still losing the specular from the material, which is arguably not a good idea, as some specular is unquestionably part of realistic lighting. We definitely shouldn't have it twice, but just wondering if we can get that render saving and still have, say 20% specular as part of a Beckmann layer for example...

The particular scene he has here has 3 main things working against it.  1) A ton of lights  2) rough reflections 3) having to up the Blurriness subdivisions to get good looking rough reflections.  Three is kind of needed with rough reflections so get rid of either one or two and you are good to go.  Minimize the number of lights needed and only have rough reflections on what really needs them to be rough.  Putting even 1% roughness with other render settings put here can double the render time.  Going from 30% rough to 0% can cut the render time by 1/4th.  So if someone really wants to save render time use rough reflections and lights only where really needed.

 

Having less lights in the scene helps will all render engines I've tested.  Less lights with GI on as opposed to more lights without GI can be faster with better lighting in render engines like Redshift, cycles, vray.  One trick that can be done if the lights used are regular lights and not spot lights is to make all the lights into a single mesh and use a illuminating material on the mesh.  This works for Cycles, Vray, and Thea Render, but Redshift does a trick where it gets non mesh lights to render way faster.  In Redshift only use mesh light only where really needed.

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  • Keeping or removing the legacy specular layer makes no real difference to render times, when you add a Beckman/ggx layer, these still incorporate specular as part of the reflection.

     

    Specular does have uses, but if you are going to the lengths of adding real reflections and using roughness to soften them, at this point imho you may as well go all the way and dump specular completely. Spec is just a fake  reflection of a light source, you may as well just add a real reflection and make a real object for the reflection to use. It certainly doesn't justify the render times.

     

    re: turn off color and just use a diffuse reflection; I can't agree here. This increases render times dramatically. Unfortunately neither physical nor standard render are that well geared to doing diffuse lighting with reflectance. I've done quite a few tests and generally sticking with the older color channel + gi lowers render times by an order of magnitude. For the scene which prompted this video, I get render times of 20 minutes with GI but no specular. 1 hour with GI and specular, but then if I switch to a reflectance based diffuse system my render times exceed 10 hours even with just 2 reflection bounces. 3+ reflection bounces gives absurd render times.

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    4 hours ago, imashination said:

    re: turn off color and just use a diffuse reflection; I can't agree here. This increases render times dramatically.

    But if that is the case, then what is happening here ? :)

     

     

    CBR

     

     

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  • Naturally there will be exceptions, but a few observations:

     

    They have picked the slowest GI method as their base standard. Double QMC is pretty much the slowest of all GI methods. This isn't something I would suggest for most people

     

    I don't see at any point if they show the render settings options page. If this is a single reflection depth, then they are essentially comparing QMC+QMC against just single QMC. Maybe.

     

    This scene has no light sources, the render times would change quite a bit if it weren't simply a hdri sky for all of the illumination.

     

    Its an outdoor scene. Reflectance materials work ok so long as the light rays can bounce off the model and escape. If you have an indoor scene with light bouncing back and forth, diffuse reflectance can get quite nasty.

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    Yep, all good points :) Thanks for the explanation... makes a lot of sense.

     

    CBR

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  • On ‎05‎/‎04‎/‎2018 at 7:52 PM, Fastbee said:

    Having less lights in the scene helps will all render engines I've tested.  Less lights with GI on as opposed to more lights without GI can be faster with better lighting in render engines like Redshift, cycles, vray.  One trick that can be done if the lights used are regular lights and not spot lights is to make all the lights into a single mesh and use a illuminating material on the mesh.  This works for Cycles, Vray, and Thea Render, but Redshift does a trick where it gets non mesh lights to render way faster.  In Redshift only use mesh light only where really needed.

    True but it gets tricky with spotlights. If you plan to model the housing unit and geometry of the light fitting then this is a good choice, but in many cases the lights in large arenas never truly get modelling, there are just a number of lights up in the ceiling casting generic light downwards.

     

    Sometimes I will swap this out with one giant area light, but then you lose all sense of having it be a series of spots casting detailed crisp shadows, all the shadowing turns into a giant blur when you end up having to use area shadows.

     

    One option I have toyed with is using one giant area light up above, then using a parallel light with hard shadows but as a shadow caster light. I'll give this a play and see if I can get any decent results.

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    10 hours ago, imashination said:

    True but it gets tricky with spotlights. If you plan to model the housing unit and geometry of the light fitting then this is a good choice, but in many cases the lights in large arenas never truly get modelling, there are just a number of lights up in the ceiling casting generic light downwards.

    With the trick Redshift does it is probably the best option if you need to have a ton of spot lights in the scene.

     

    On 4/8/2018 at 4:52 AM, imashination said:

    Specular does have uses, but if you are going to the lengths of adding real reflections and using roughness to soften them, at this point imho you may as well go all the way and dump specular completely.

    This is a good point.  For maximum realism a reflection with fresnel, roughness, and no spec is the best.  It is nice having the spec option for artistic purposes though.

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  • Here you go, give this a go. Using one area light for the illumination but splitting off the shadows.

     

     

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