Tips & Tricks for Iray for newbies......

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  • HoopsterHoopster Posts: 6
    edited December 2015

    I'm really strugging with getting a clean render. The issue I'm running into is grain, heavy heavy grain. When I render just a model with no environment everything is good, it looks great with no grain in just a couple minutes... but when I put them in a room that completely changes. I've tried upper the ISO. I've tried upping the Luminescence of the lights. I've tried turning on the Firelfy and Noise filters. Nothing seems to help. I have to let the render go for a very very long time (hours upon hours) for it to get better. This isn't an option as I do animations.

    I can get a great looking render outside of an environment and simply using a backdrop image to simulate one in under 10 minutes, so what is it about environments, even after filling it with emitter lights, that is causing me a problem?

    The bulk of it seems to come from using lights other than the camera's headlamp. if the headlamp is the only light in the scene the grain is basically going, only sticking around in very dark areas (strangely, the longer the render goes for the more white dots appear in the dark).

    Post edited by Hoopster on
  • Oso3DOso3D Posts: 14,414

    My advice is to put one or two point lights in the room, leave Tone Settings where they are, and crank up the Luminosity until it starts looking reasonable (I suggest changing scale to cd/cm2 for sanity's sake).

    IF that works, then start distributing out the lighting, focusing on trying to use point/spot lights with geometry wherever possible.

    Related question: how are you lighting those rooms?

     

  • scatha said:

    Right, so the render acceleration is ONLY going to work for people with an NVIDIA graphics card... which seems ridiculous to me.

    Wrong all it means IF YOU HAVE A NVIDA CARD that will be your render engine otherwise YOUR CPU will be doing that work

     

  • My advice is to put one or two point lights in the room, leave Tone Settings where they are, and crank up the Luminosity until it starts looking reasonable (I suggest changing scale to cd/cm2 for sanity's sake).

    IF that works, then start distributing out the lighting, focusing on trying to use point/spot lights with geometry wherever possible.

    Related question: how are you lighting those rooms?

     

    With emission lights. Largely these: http://www.daz3d.com/real-lights-for-daz-studio-iray

  • KhoryKhory Posts: 3,848

    I'm going to disagree and say that you should go ahead and adjust the tone mapping for the type of lighting you expect to be rendering with just like you would have selected a film for the type of lighting you would be photographing with back in the day. I always start with 200 unless I am doing an outside render with very bright sunlight. Most interior images I start at 300 or 400 ISO. If I notice that the light seems to be playing out before it gets to the back of the room I will also lower the f/stop as that seems to help with that.  I do agree that adding at least one photometric light seems to help with grain and speeding up render (because the darker the image the longer it will take to render and the more photometric lights you use the faster the render) but I tend to swap it out to a rectangle or sphere and make it at least 30x30 so that it is a rather diffuse light sorce and will not cast harsh shadows. If I can add more of those and not confuse the lighting in the scene I do. Again to speed things up.

  • evilded777evilded777 Posts: 2,387
    Khory said:

    I'm going to disagree and say that you should go ahead and adjust the tone mapping for the type of lighting you expect to be rendering with just like you would have selected a film for the type of lighting you would be photographing with back in the day. I always start with 200 unless I am doing an outside render with very bright sunlight. Most interior images I start at 300 or 400 ISO. If I notice that the light seems to be playing out before it gets to the back of the room I will also lower the f/stop as that seems to help with that.  I do agree that adding at least one photometric light seems to help with grain and speeding up render (because the darker the image the longer it will take to render and the more photometric lights you use the faster the render) but I tend to swap it out to a rectangle or sphere and make it at least 30x30 so that it is a rather diffuse light sorce and will not cast harsh shadows. If I can add more of those and not confuse the lighting in the scene I do. Again to speed things up.

    I'm with Khory, for the most part.  Very good advice. But if you are doing animations and time is an issue, and if you don't have some serious hardware to throw at the problem, you will probably find that more and brighter lights at the default Tone Mapping settings will be faster. This is just one of those situations where you have to employ some of the real world tricks that photographers and flim makers employ...fake it.

    And, well, frankly you are not going to have much luck trying to light something entirely with emissive surfaces.  Its a great idea, but it takes a lot... a lot of surfaces and a lot of light. I've seen it done and done well (look at some of Stonemason's newer sci fi sets), but... its not for the faint of heart. You have a toolbox, you really kind of need to use all of the tools at your disposal. ( I fully expect to get beat up for this paragraph.)

  • KhoryKhory Posts: 3,848

    I think that emissive lights are more of a secondary bounc while photometric lights are more a primary bounce. Primary bounces work faster and fill in the image more quickly than the secondary bounces. How much light the scene has is also going to be influenced by things like how light/dark walls are etc because light walls will bounce back more light than dark walls. I'll actually be testing times etc for emissive lighting this week as I finish up a product that has a couple of light props that are emissive. If I sort out anything helpful I will post.

  • Oso3DOso3D Posts: 14,414

    An emissive object requires the renderer, as I understand it, to calculate light emitting from every polygon.

    Using an in-built primitive (point/spot with geometry) generally drops this down to either a single polygon or an otherwise optimized simplified object.

     

  • Hoopster said:

    I can get a great looking render outside of an environment and simply using a backdrop image to simulate one in under 10 minutes, so what is it about environments, even after filling it with emitter lights, that is causing me a problem?

    As far as render time goes, its about light bounces. Interior scenes have lot more surfaces for light to bounce around than 1 backdrop image or hdr environment map so they take longer to calculate.

    It may also bee that lot of additional stuff needs more memory than what your graphic card haves so it drops out of the rendering and you are rendering with CPU only.

     

  • kyoto kidkyoto kid Posts: 35,504

    ...the attraction for myself with emissive objects In Iray is that I can light a scene with the "light" props provided without having to rig up and place a large array of spot/point lights like I needed to do in 3DL.  Yes, it takes longer to render, however if you are going to portray "realistic" lighting from props in a set, whether in an indoor or or nighttime outdoor scene, you just have to deal with it.

    If the scene calls for photometric spotlights (such as for say, a stage performance/concert, or headlights of vehicles) then yes, I include them.

    This is why I need a Titan X (or two).

  • TinjawTinjaw Posts: 50

    Having seen this thread for the first time today (I am just starting to work with Daz Studio) is there any summary available of this thread or do I just need to grab a six-pack and read all 36 pages? cheeky

  • Having seen this thread for the first time today (I am just starting to work with Daz Studio) is there any summary available of this thread or do I just need to grab a six-pack and read all 36 pages? cheeky

    Better make it a couple of six packs.  However, I recommend a bold strategy of reading it in reverse order so your mind is a little more clear for the most recent information.

  • ScavengerScavenger Posts: 2,664

    Guess I'l ask here...I'm using Bacon the toon dog..I tried the OOT Hair Shader on him for iray, and it seems like it looks good, but the hair/fur is WAY too shiney.

    What would be the settings I want to play with to try to fix it?

  • The OOT hair shaders have some presets for changing the amount of shine.  I think they're in the "gloss options" folder? Sorry, not in front of my PC to confirm the folder name.  Alternately, you can play around with the Glossy Reflectivity or Glossy Layer Weight sliders.  You may also need to adjust the Top Coat Reflectivity if Top Coat is set to Reflectivity (not Fresnel).

  • ScavengerScavenger Posts: 2,664

    Yeah, there's glossy presets, but they seem to go glossier, not duller :(.

     

    I'll try the fields you mentioned, thanks!

  • Alright, so I threw in a couple of photometric lights and it definitely improves things massively, however I'm running into an issue in regards to shadows. 3Delight allowed me to turn shadows off on lights, but it is greyed out on the photometric lights. Is there anyway I can deactivate these lights from casting shadows? It gives me the light I need, but the only light I want casting shadows is a specific emission light I have in the scene.

  • Oso3DOso3D Posts: 14,414

    Iray can be Photorealistic or Interactive (Render settings > Render mode)

    In Interactive mode, you can set the ability of lights to cast shadow or objects to throw shadows, in photorealistic mode, you can't (thus, 'realistic')

     

  • Oso3DOso3D Posts: 14,414

    And, on that note, most people have been overthinking Skydomes, myself included. We've come up with all these exotic workarounds for the strict elements of Photorealistic renders.

    But people keep pointing out... there's also Interactive.

     

    If you want to easily set up a skydome, or convert one from 3DL... it's not hard. Switch to Interactive, the skydome's 'doesn't cast shadows' is preserved. You can shut off most of the lights except whichever is supposed to be the dominant 'sun' glow, make the skydome minimally emissive (say, cd/cm2 around luminosity 1-2), and there you go. If you want much more diffuse lighting (like, not a bright-sunny day), you can shut off most of the lighting and apply sun/sky or a HDRI lighting low-resolution thing, or... whatever.

     

     

  • KhoryKhory Posts: 3,848

    In the real world you can't cut shadows but you can minimize them. The larger the size of a photometric mesh light the more diffused the shadowing will be. Changing the light from point to a shape and then the increasing the height and width of that shape will go a long way to muting shadows. I'd start with at least 30x30. If that does not fully resolve the issue then you can add another light from the other direction to help cancel out the shadow.

  • Oso3DOso3D Posts: 14,414

    For example, here is a quick 5 minute render.

    It uses Ocean Wide and the Ocean Wide skydome, and a Greek ship model.

    Steps:

    Ocean wide, add Ocean Calm and Midday skydome.

    Convert all materials to Iray Uber Shader

    Change skydome emission to cd/cm2, luminosity 2.

    Hide all lights except Sun-on, make it Photometric, set Luminous Flux to 10

    Change render mode to Interactive

    Change Ocean Calm displacement subd to 3.

     

    And... that's it.

     

    Skydome Test.jpg
    2000 x 1236 - 1M
  • FishtalesFishtales Posts: 5,346

    I know you haven't spent a lot of time on that image Will but there is a lot of banding and the there is hatching where the Iray transparent dome is showing through The sky dome.

  • Oso3DOso3D Posts: 14,414

    Heh. No, there isn't... there's no transparency at all!

    The issue, I'm pretty sure, is that it's simply not a very high resolution backdrop (4096 x 2048), and Iray is less forgiving about stuff like that. I could obscure the problem with depth of field.

    But hey, proof of concept. I had to do very little work. If I substitute in a much higher resolution image, then hey, bob's your uncle.

     

    One downside of Interactive mode is that SSS doesn't seem to function, alas.

     

  • Oso3DOso3D Posts: 14,414

    Anyone have tips for rendering clouds?

     

    I've been wrestling with SSS, translucence, and countless other things for almost two days and it's driving me crazy. I can't get shadows to look distinct through a cloud, I can't get a cloud surface that looks nice... argh.

     

  • KhoryKhory Posts: 3,848

    How are you doing the clouds and what lighting are you using for the sun?

  • Oso3DOso3D Posts: 14,414

    I have a look that's working ok... using Ocean Wide with a displacement map (displacement maps have been... problematic, with SSS, load-wise) and a lot of SSS.

    Been using Distant light, trying to get as sharp a shadow as I can manage. Also experimented with a bunch of other things.

    Render is SLOW. 2 hours in, at 126 iterations and 33% convergence. Woof.

     

  • Iray can be Photorealistic or Interactive (Render settings > Render mode)

    In Interactive mode, you can set the ability of lights to cast shadow or objects to throw shadows, in photorealistic mode, you can't (thus, 'realistic')

     

    When I switch render mode to interactive I just get a blank render.

  • JimmyC_2009JimmyC_2009 Posts: 8,891
    Hoopster said:

    Iray can be Photorealistic or Interactive (Render settings > Render mode)

    In Interactive mode, you can set the ability of lights to cast shadow or objects to throw shadows, in photorealistic mode, you can't (thus, 'realistic')

     

    When I switch render mode to interactive I just get a blank render.

    You need to go to the Advanced tab in the Render Settings pane, and in the bottom half, you will see Interactive Devices, you need to put a check mark in the box or boxes of the devices that you want to use..  I will work with CPU or GPU or both, just like the other mode, but you need to tick the boxes first.

     

  • Hoopster said:

    Iray can be Photorealistic or Interactive (Render settings > Render mode)

    In Interactive mode, you can set the ability of lights to cast shadow or objects to throw shadows, in photorealistic mode, you can't (thus, 'realistic')

     

    When I switch render mode to interactive I just get a blank render.

    You need to go to the Advanced tab in the Render Settings pane, and in the bottom half, you will see Interactive Devices, you need to put a check mark in the box or boxes of the devices that you want to use..  I will work with CPU or GPU or both, just like the other mode, but you need to tick the boxes first.

     

    I already had, but I just had my GPU ticked. So I ticked CPU as well and that does give me a render... but it only renders for a couple seconds and then "completes." I changed my render time to default and that fixed it, I guess "0" in Interactive means literal 0 and not "off" like it does in Photoreal? Also I'm guessing interactive doesn't use your GPU and instead renders only with your CPU? Otherwise why wouldn't it render anything with just GPU ticked?

    Also it seems that my emission lights aren't working in interactive either. I'm guessing this mode really changes how things work?

  • OstadanOstadan Posts: 1,080

    It's probably pretty well known, but I hadn't realized that some images used as environment need to have their gamma corrected.  Here I have used a star map from NASA (https://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=3895) applied as the environment map, with a single distant light and a prop.  On the left, the image is used unchanged.  It doesn't look right at all, much too bright.  I took it into an image editor, applied a gamma of 0.454545 (the inverse of the normal 2.2 gamma that is applied to the image) and rendered again to get the result on the right, which is the result I intended in the first place.

    falcon-nogamma.png
    800 x 600 - 896K
    falcon-inverse-gamma.png
    800 x 600 - 659K
  • DanaTADanaTA Posts: 11,986
    Ostadan said:

    It's probably pretty well known, but I hadn't realized that some images used as environment need to have their gamma corrected.  Here I have used a star map from NASA (https://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=3895) applied as the environment map, with a single distant light and a prop.  On the left, the image is used unchanged.  It doesn't look right at all, much too bright.  I took it into an image editor, applied a gamma of 0.454545 (the inverse of the normal 2.2 gamma that is applied to the image) and rendered again to get the result on the right, which is the result I intended in the first place.

    Actually, the image on the left seems to show a very dense star field and a nebula.  The nebula doesn't even show up in the one on the right.  It may be what you wanted, but it doesn't seem to be true to the image you used.  Just an observation.  I don't know if this is just a portion of the image on that page, or if the page has changed.

    Dana

     

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