Help with image lighting and grain
Hello,
I'm new to Daz, obviously, and trying to figure out how to light a scene. I'm using iRay, and trying to follow some tutorials... I'm not always sure they are applicable sense many are for older version.
In the attached scenes, I have sort of a half dome environment map. I put an iray shader on that, and have it casting a 3500k temperature light at 15,000 lumens. I then made the glass bulb objects in the scene also have iRay shaders, set the emission color to pure white, and have them casting light at 10,000,000,000 lumens.
My renders are taking hours. I have no actual lights in the scene, just the iray uberbase shader applied on a few objects. My renders come out grainy, or incomplete, and I'm not sure why? I'm never around when the render finishes so I'm not sure why it stops, but I'm guessing there is some setting? I have a few questions...
- Is this a good method of lighting a scene? Using no actual lights?
- Why do I need so many lumens, and the image is still relatively dark? Is the light reflecting off surfaces or do I need to do something to simulate or activate this?
- How can I preview or see what I'm doing? With no lights, everything in preview window is just dark.
- How can I make a high quality still image without the grain?
- I'm using CPU rendering because I have an ATI card. I see something about cloud rendering servers in the rendering settings. Are there any servers that support this?
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Hi. I'm a newbie too, but I'll try to help you out with what I've learned so far. Are you sure you're using lumens for your skydome? 15,000 seems really low, like barely visible when I tried it on my computer. I don't have the scene you're using, but I have a similar one from Stonemason.
I'll try to answer your questions as best I can
1. I use domes with emissive shader applied and it works fine for me. Some people say it's much slower than using DS's built in environment dome, but I haven't had a problem.
2. I wonder the same thing. It seems like light isn't reflecting the way it should. I haven't figured it out yet. The only thing I can imagine is that Daz Studio, your graphics card and your screen only have a limited range of values they can display. That's why scenes look poorly lit compared to looking at the real world with your eyes and brain which have more advanced image processing. Just like how you can look at a poorly lit room and see everything just fine, but you'd have to add a lot of lights to take a decent picture of it.
3. You might have the light simulator turned on in the preview window. Press CNTRL-L to toggle it on or off. It helps some, but not enough in my opinion.
4. More light. It seems counterintuitive because biased renders get slower when you add more light(more calculations to do). Unbiased renderers seem to go faster with well lit scenes, but your mileage may vary if you're in CPU mode.
5. Apparently, the cloud rendering will be a future upgrade. I just hope they have local network rendering so I can add a second computer with video cards. OpenCL would really be nice so I could use ATI cards, but that's not likely to happen.
Long story short, I'd hide the skydome for now and just use DS's built in dome for reference. Just like in real life, the light bulbs in the room should barely make a difference because there's so much natural light flooding in through the windows. Then experiment from there.
No, it isn't.
Use actual lights, or at least an HDR image (with or without showing the image; you get its light nonetheless). They connect to primitive types internally supported by Iray. Pretty much all of your issues will be resolved if you don't try to use emissive geometries for all your lights.
If you want the diffuse look of an emissive (diffuse is the only kind of light they will produce), use a spotlight or point light and change the emitter type to a plane geometry -- rectangle or disc. Now enlarge its size. The bigger it is, the more diffuse the lighting, and less distinct the shadows.
Actually I disagree with Tobor. Here is a WIP I'm doing re-texturing the Tuning Garage from over at rendo with Mec4d's fabulous PBS shaders Vol 2 for Iray. There are no "real" lights, I used Real Lights for DAZ Studio Iray and applied the 85 watt Florescent preset to the light tubes material on the fixtures hanging from the ceiling. Also set the environment to scene only to only use the emissive lighting with the camera headlamp disabled. As you can see it does a great job lighting the interior on its own. BTW, I HIGHLY recommend that set of shader presets for Iray, it has everything from incandescent to neon to campfire to monitor screen settings and is super easy to use.
Click for full view without forum distortions.
It's all about speed, and with speed, faster renders to get full convergence. You could eventually get a scene with one emissive set as a single candle flame, but in Iray, it would take a very long time to render. That's simply how it works.
You could also have lit that garage with spotlights (or point lights) shaped as cylinders for actual fluorescent tubes, or as flat rectangles for ceiling fixtures, and likely achieved the same results in less time. The lights fixtures in D|S are connected to internal Iray light sources (point, area, infinite, etc.), so they are simply more efficient.
Mesh lights arfe very good for providing in-scene lighting -- the glow of a TV screen or lamp, for example. And, they *can* be used for scene illumination. But all things considered, with speed of render on less capable hardware being a main factor, if you can light using the built-in light types and achieve the same results, then why not?
The best for iray are emitter shaders as they best response to IES profiles , the fastest are point light with IES profile and Caustic On for indoor scene ( all walls closed no empty scene ) it render 50% faster than without caustic however the IES is not as much accurate compared to sphere with emissive shader and IES , when you use IES you don''t need any spot light as IES will give you any type of light you want on a simple sphere with emitter , from spot light to diffused light and looks most realistic .
@Tabor it is all about the right settings , DS light give you some quicker alternative but they are not even full spectrum so just alternative and every render outdoor or indoor looks like in studio because of that
the trick is not to convert full cube or sphere into emitter and if you do you need to use IES profile , why you would use worthless spot light if you have option to use 1000 different light source and very accurate too
candle light from point light will not render faster than emitter but what the most problem is people render in open or half open scenes and the 50% of photons escape , image like this will never finish in render
also after many tests , I see that having Caustic on (only) in closed scene will render 50% faster than with Architectural or no caustic at all , another thing is using glass in windows it will change the indoor light dramatically when using outdoor light source and on the end proper surfaces , if set bad the photons will be absorbed and they need to be reflected so the rest of the scene get the proper light
I look at sledgeweb render and it looks like each lamp have 5 -10 watt the scale of geometry will affect the light power so the 3D bulb need to be modeled correctly to have accurate light proportions that is when IES profile come in handy as it tell the shader what to do without wasting the energy .
In unbiased rendering HDRI, Sun and Light emitters are the key or you just cheat with some spot light and the results will be different in the appearance and mood but what you do is of course personal choice , how you made your bed so will be your dreams
but coming back on
Iray is your virtual camera, you need to learn how to setup your camera (tone mapping ) so the rest work too , if you use the standard camera tone mapping in iray that is set for Sky sun by default and try to render 100W lamp you get what you setup , thats not the light issue but your camera aperture . Indoor rendering is not different from taking photos at night indoor , what often result in too many noises too because your lens aperture is too high or your iso too low , same in iray , it is physically based so little photography study about how to take photo indoors will help a lot to understand what is going on and how to set the tone mapping for each situation in place to find cheap alternatives to boost the light , and I swear that half renders I see in the gallery I think was done with 3DL , that are the results of it and the answer and fix is very simple , you got great tool in your hand so do some study , things will be much easier after
This flies against Nvidia's documentation. Point light also accept the same IES profiles, so there's no loss of function. A big problem with mesh lighting is that they are, by definition, diffuse, making them less useful overall. You can readily see this in the shadows of renders.
Where do you get this? D|S lights connect to Iray internal light sources; Iray primitives are photometric, so their response is based on the human eye. This is different from radiometric (which would give you contuinuous tone from ~400 to ~800 nm), but which is not ideal for real-world rendering. Saying Iray lights are not "full spectrum" would be a surprise to a great many architects who use the renderer for accurate depictions.
You understood me wrong I don't say Iray light don't have full spectrum , I say Daz Studio point light and I had reason to say so as you will read below , I use unbiased rendering for years so I am familiar with the terms and how it works .
but back to the subject about emissive shader , the shadow can be diffused or not
you can have the same hard shadows exactly as in point light you just need to scale the emissive geometry to 0.1% to have the same effect as point light shadows and of course use IES profile for best result
Another bug in DS is when using emissive shader together with DS point light and you change the values under the shader it turns off the point light so need a shake before it turn on so something is sill not right here and may be another DS bug
I just updated my Daz Studio again and can confirm that now the DS point light have full spectrum as well so in the case of full spectrum I was right but that was DS doing it , but the issue with the point light together with emitter still exist
the light emission with the same IES profile is actually the same now after updated DS so it may be some bug I had or bad install of 4.9 and they render at the same speed , I made some tests and both rendered in 2 second separately and 2 second together
If you scale down the emissive geometry to 0.1 % to match the point light both have the same values and IES profiles and hard shadow I guess they become just the same as at this stage they render exactly in the same time , another difference here that with emissive shader light you can see caustic and chromatic dispersion through volume , but not with point light or any other light source in iray like HDRI or Sun Sky but emissive shader geometry need to be at 100% scale and you compromise here you hard shadows , the geometry can be just 1 mm but still 100% in scale
as I said the shadows are the same in both , you want to have soft fall off shadows change the scale slightly to 0.1%, if you go below 0.00010% you divide the emitter into 2 light source in one when using IES Profile
the reason that emissive shader render slightly longer is that is calculate more information than just point light but not huge difference
I made some previews for comparison and my conclusion
in image 3 the e-shader produce brighter light when scaled to 0.1% with the same strong shadows but when scaled to 100% it get automatic dimmer losing its hard shadow and become more diffused as that is how emissive shader work but it produce more accurate effect at the end ..
all render time just 2 second , the same setting for both
The only conclusion here is that the DS point light is nothing else than iray emissive shader on primitive geometry scaled down below 0.1% and nothing else , I can check the MDL code but I am sure it is the same as nothing else is there
I have any kind of light that exist in physical world as it is just the most versatile light you would ever want , why settle for less if you can have it all with so much better control in overall .
it is 1 vs Unfinite
I wouldn't worry about it too much. I've noticed that lots of vendors don't care about serious grain in their promo images... no names mentioned. Perhaps grain will catch on.
look I used only 6 cm cube with emitter and IEC profile inside of a 8 ft cube on top my PBR shaders, render time 1 min and 50 sec, 600 iterations and not bad , especially that half of the render is just global illumination without any direct light pointed on it , if I did it would be half the render time .
I can move my scene in real time and adjust light just like with HDRI
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Cath, you need to try your renders with GPU-assist turned off. CUDA cores are optimized for the floating point math used in ray trace calculations, so to get a sense of how "the real world" user experiences it, render on a machine with only CPU, or a nominal number of cores, say 500 or so. Having lots of cores gives a false impression. The difference is exponential.
I do understand there is value to all the light types in Iray, but it's best to understand the primitive light sources in Iray are there for a reason, and that's efficiency across typical use cases. I have not experienced the bugs you mention, so I can't comment on those.
In re-reading my previous reply above, I was not clear about about emissives only being diffuse. In the Uber MDL the switch is for profiles or diffuse edf. It's not just the size of the emitter that comes into play, but the nature of exitance of the ray paths. In any case, this parallels point lights when the emitter is changed to an area primitive.
Where users get hung up are the vagaries of mesh lights because of the potential for compounding parameters, which do not exist when using lights from the Iray ILight API. Exitance calculations are massively increased as polygons are added; even more calculations are required when the surface is complicated with non-emissive properties, such as reflectance. These issues are endemic of emission from arbitrary geometry, and you want the choice, so you have to take the good with the bad.
As yet, there is no simplified emissive shader that comes with D|S that helps users avoid parameters that can cause their renders to slow to a crawl. I've learned that for the typical user, these factors can be confusing and frustrating. It's just better to suggest using the core lights, which connect internally to the Iray API. Light profiles are fun, and all, but we could probably count the number of people who use them on one hand. It's a very underutilized feature, regardless of the light source.
Well Tabor , I do test often my shaders on CPU only to make sure all works fine and fast , I diid also tested the light preview on CPU , where the small images was rendered in 2 min, they rendered in 48 sec with CPU
and I agree with you on the point that for new user it is better to start with simple standard light in place of messing with something they don't understand yet totally and how proper use it
but if people want more there is no reason to turn them back to the basic or they will never learn the full potential , they need to learn by errors and mistakes, knowledge need to be converted to practice or all you have is just artificial intelligence , .There are situations where base DS light is pointless and totally not usable think here about rendering glass or metal scenes where reflection of the diffuse light is crucial for the result , how many people complain that metal and glass render black in the scene , because all they used was point and spot light on a very reflecting surface so in this case they need to step up in the game .
here is my simple scene setup to render glass or any reflective surfaces using 2 emitters, 1 poly face per light just to give the idea where other type of light are not usable , not in iray or in real world situation and the tricks I use in my real Photography workflow works perfect in iray all the time , I also added some point light for the backdrop deeper dimension in the second part for faster workflow
simple and effective and first day user can do that , if I need it to be perfect and accurate I would spend couple of hours to adjust everything to perfection but everyone need some start point and idea to grow and practice
For me, with a CG background, I almost never use mesh lights except when creating a practical lamp that shows in the scene. Everything is HDRI, and usually some spots or points for fill. I don't think I've ever gotten a black mirror, though I can understand how that might happen to someone. I think it's all how you use the tools.
Because you use the proper optimal way and so I do as HDRI are my favorite base lighting but people put just mirror ball in empty scene only no hdri without even ground plane and one spot light in front and not happy that the metal is black .. funny but that is the reality with newbies in iray .