I have been comparing ways of simulating ambient light in 3Delight renders. I thought I would share some comparison renders I did for an outdoor test scene. This is very simple scene, a model and a sky dome. The lighting for the images are:
No Ambient - One distant light, intensity 100%, Color 255, 246, 234, Raytraced Shadows, 1% softness, Render time: 3 m 51 s
UE2 - Distant light as above but intensity 50%, UE2 intensity 50%, color same, Occlusion w/Directional Shadows, HDR KHPark preset rotated to align with distant light, 3Hi quality preset. Render time 6 m 40 s
Distant Lights - One distant light as in No Ambient, but intensity 70%, 6 distant lights to add ambient, intensity 20%, color same, diffuse only, no shadows, Xrot -10, YRot of 0, 45, 90, 180, -90, -45. Render Time: 3 m 53 s
Ring of Light - One distant light as in No Ambient, but intensity 70%. Ring of Light (no sky, just the light), Ambient 3.0 preset, Sky 03 Light preset (color 255, 255, 208), Quality 3 preset. IMPORTANT NOTE: You have to turn the opacity of the ROL to 0% in the surface tab, otherwise the ROL blocks the distant light and you get only ambient light. You can do this for the whole ROL at once, don’t have to do it for each of the 36 sections. Render Time: 1 h 17 m
UE2 Soft - same as UE2, but used Occlusion w/soft shadows. Render time: 6 m 48 s.
UE2 Ambient - same as UE2 but used Ambient mode. Render time: 3 m 58 s
Luxus - LuxRender via Luxus. One distant light translated to sky2. Only material setting was glass for the eyes. Render time: around 9 h, 5k s/p. Note: there are problems with materials. I’m a newbie with LuxRender. LuxRender gave errors about the tif files for the eyes, which is why she has demon eyes. I think Luxus is lowering the resolution of all the textures by default. Translation of skin textures/shader seems weird. The DAZ skin material uses UberSurface and includes subsurface scattering. The way Luxus translated that makes the skin look strange to me.
I have posed the model looking directly into the sun. As photographers know, you should never do this. The dynamic range of a camera is not as wide as the human eye. Pictures posed like this come out badly unless you use fill flash. However, I’m not trying to render an image that would look like a photo, and the human eye has wider dynamic range than cameras do.
The no ambient image shows the harsh shadows you get with just a distant light. I’m guessing the Luxus image shows how much ambient scattered light you would really get, but I don’t like the look of this image because of the material issues.
I have never been able to get UE2 to produce result I like. Maybe I gave up too quickly on UE2 and never learned how to use it correctly. I get results I like better using multiple distant lights to fill in the ambient and it renders faster than UE2. The Ring of Light produces very good looking results too. There is a slight difference between the Distant Lights and Ring of Light images in the amount the shadows are filled, but this is just a mater of adjustment. You can independently raise and lower the ambient intensity in both of these images.
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