Grainy shadow
hapciupalit
Posts: 123
I know it's quite a comun subject this one, but after reading a lot of threads I still have a shitty result.
Here is a render I made. To be honest it's better than a few months ago when I started to use Daz studio, but why I don't get it's why I have that grainy shadow?
I got a GTX 1080TI and this render took like 1 hour. What can I do to get rid of the grainy effect and make the renders go a little bit faster.
I use distant light to make the light come in the room and also I added some point lights. I'm not sure if it's ok to do like this, but I could really use some sugestions.
Thank you
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Maybe adjusting the shadows so they're not so dark? It's the dark areas that are worst when it comes to graininess.
Also, for indoor lights, mesh lights seem to give better results than the standard DS lights, IMO.
How can I adjust the shadows?
The simplest way would be to add more light. At the moment, it looks like all your light's coming from the left. If you add a mesh light on the right side, you should see a marked difference, particularly with the darker skin.
You may need to put your cutlery on the table, too
Haha... yeah... I already placed them on the table but I didin't render anything unless I understood how to create a better light. One more quesiton. What a mesh light means exactly? It's a flat object with luminance? or?
Essentially, yes. But, I'm not the best person to explain these things - been a long time since I fiddled with lighting in 3dl and I don't use iray.
Oh ok... Thank you anyway.
"and make the renders go a little bit faster."
You could hide some geometry that is not visible, like the legs of the people. Mind you that you don't want to hide everything that is not visible, because those things will still reflect the light back into the scene and give it a tint (and help reducing grain actually). If you remove everything, the light bounces out to nowhere, not adding to your scene. So, hide smaller things, or things that are never visible in any way, like legs in a trouser. It reduces the overall load a bit, because less geometry = less calculations = more speed.
Edit: This tool comes in very very handy, when you want to disable parts of a mesh without going insane:
https://sites.google.com/site/mcasualsdazscripts4/mcjhideallbut
Just place it into the scripts folder of your content library.
"Grain"
you likely get that because there is not enough light bouncing around. Noise will get away eventually, but it can take a looong time.
You seem to have a single light source on the left. In order to light (or shadow) the characters from the right, the light needs to bounce around, so it can hit the people from the right. If you have not enough light sources sending out light rays that bounce around, you need a lot of iterations to get the shadowed parts to not look grainy - because it takes a lot of time for enough light rays to get to these areas, whereas, like on the background, the light can hit it directly and much more light rays hit it, resulting in less grain.
You could place a soft (read: big) mesh light on the right and balance the power between the lights to keep the overall lighting intensity. E.g. reduce the power of the left light a bit, be gentle on the power of the right light, it's only there to send more light into the scene, not to remove shadows by brightening everything up too much.
To create a mesh light, go to the menu bar -> "Create" -> "New Primitive".
Chose a plane, world center, axis as you wish (x positive pointing right, x negative left, z positive towards you, ...), 1x1 meter (you can rescale it later) and 1 subdivision.
Select the plane. Go to the surfaces Tab and also select the plane there. Go to your IRay shaders in the "Shader Presets" in the Content Library tab and apply the "Emissive" Shader. Play around with the emissive values in the "Surfaces" tab to control the strenght and color of the light (Emission Color, Emission Temperature (lower=more redish, higher = more blueish). and "Luminance" for the intensity.
Edit: And check that your room is not open on the right side, e.g. because you removed a wall. Again because it will bounce back the light into the scene and help reducing the grain.
In general, in photoshoots, a lot of efforts go into the lighting. What often looks like a random scene with a sunlight, actually has a lot of lamps around the scene to give it a balanced overall lighting. That's something we need to learn to immitate, it wasn't that important years ago, but with the new render techniques, one actually has to learn a little bit about photography.
It definitely helps and actually is interesting.
That's my take on your question. Next one, please. :D
Create a Plane primitive, apply the Iray Emissive shader, set Cutout Opacity to 0.0000001 to make it invisible. Adjust Emission Temperature (e.g. 5500) and adjust Luminance for strength.
Or purchase this one: Iray Ghost Light Kit - https://www.daz3d.com/catalog/product/view/id/36389
First of all, Thank you for your huge resposne.
I'm a little bit confused on some things. Well in my case there is a livingroom close to the kitchen and some other rooms. When I'm rendering the pc is still calculate the objects from another room? And this make the render time go slower? And if I hide the bed from bedroom, some coutch from the livingroom which will make the render faster? or just the itmes hidden in the preview like shoes, legs etc?
I have found also Iray Ghost Light Kit 2. Do you think it's an update for the first one, which will make him better? or is something else and I should buy the first one?
To be honest, I have no clue about when and what the iRay engine excludes from the rendering, if it is not visible.
But this is how I think it should work:
In a game engine, you would hide everything that is not visible - for speed reasons.
In a render engine, where speed is not the primary objective, but realism is, I'd expect the engine to not hide "invisible" things when rendering, because, while it is not visible, it will still reflect/bounce light, which adds to the overall scene. Some things more, some things less. Maybe you have a very detailed wall clock in your scene, which you cannot see because it's outside the view - you should hide it, because it won't reflect much light, hence it is not contributing to the rendered scene, but because it has many polygons the calculations, which you don't need, take their time.
I'm pretty sure that it does calculations for e.g. a leg, even if you cannot see it because it's inside the pants. Not sure about offscreen objects, but I try to keep most of the big (in size, not polygons) ones enabled. Smaller things, like a couch, a table, a glass and such, I disable. On characters, I disable the teeth, if the mouth is shut, or the gens, if you cannot see them anyway. Every bit helps (I'm on CPU rendering).
In the end, one has to try it out. But don't expect wonders.
Back to your questions:
"When I'm rendering the pc is still calculate the objects from another room?"
It should, yes. because it cannot know for sure, which objects are not important and which are. Important in terms of adding to the scene, light-wise.
Imagine you have a mirror on the right side of your kitchen. You cannot see it, but it definitely would reflect back the light coming from the left side, back into your scene. If you disable the mirror, there should be a noticable change in the scene lighting. Same goes for every other object, but it might not be as obvious as on a strong reflecting surface like a mirror.
Some objects are really not important and you could/should hide them before rendering, but I'd always keep the walls, floors, ceilings.
"And this make the render time go slower?"
Yes, because more calculations and more light rays are needed to converge the render.
"And if I hide the bed from bedroom, some coutch from the livingroom which will make the render faster?"
It should, but not sure how noticable it is. It depends on a couple of factors.
"or just the itmes hidden in the preview like shoes, legs etc?"
That should help too, yes.
Someone please correct me, if that's all nonsense. This is how I understood things work. :D
Looks like a standalone product to me. But all it does is to make things easier for you to set up. It does nothing that you cannot do on your own, Taoz described how to do that - the result is the same as in the Ghost Light Kit. The product still makes the setup a bit faster, you decide if its worth the price for you. :)
Thank you very much. I'm going to try again the renders with what you told me. I hope it will be better and faster...
Best regards
I'm using version 1, I'm aware of version 2 but it's my impression that it's more for making lamps and other light sources which I'm not really interested in so I haven't purchased it. Version 1 works fine for me, it makes it easier and faster to create mesh lights so I prefer to use it instead of creating my own.
Uhum... I got a strange thing ... When I add the mesh light I also render the red arrow... Do you know how to get rid of it?
I'd add more light. The black character in particular needs some extra soft lighting.
In general Iray renders shadows very grainy even sometimes with adequate light. If you don't have a monster computer to let the render render a long time this is just one of the annoyances you have to deal with.
Only the arrow or also the red-black checkerboard? If only the arrow, you've done something wrong (like setting Cutout Opacity for the light only to 0). If both, just select the light and apply the "Apply before presets" preset. The arrow/checkerboard is just so you can see what you're doing when positioning it, after that you remove it with that preset. You can also use the selection frame which shows when you select the light, to see its position, it's usually good enough for fine tuning. Create a camera for your main scene view and then shift to Perspective View (or use another camera) for positioning and adjusting the light, that's the easiest.
I seem to have noticed that it's more "grey" areas that get grainy rather than very dark or black areas.
It worked... Thank you very much