Denmark
Joined: Jul 7, 2013
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Image Based Lighting (IBL) – adding a new dimension to SH3D
The image is rendered at 12PM (midnight), completely without traditional light sources.
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IMAGE BASED LIGHTING
Having used a number of other 3D software for some years, Image Based Lighting(IBL) have often been the solution when trying to match renderings of 3D models to photographs or images rendered with other 3D software. But since there is no IBL-option in SH3D, I have always thought that using IBL was not possible. It wasn't until Enkonyito pointed out that the last version of the Create photo with renderer in fact offers IBL through the Enhance external brightness-option, that I learned that it's absolutely possible to use IBL when rendering SH3D photos – you just have to know how.
Some of you probably know about this technique already, but to me it was like a revelation when I started experimenting, based on my new insight, and found that using IBL was a vast improvement – and it's quite easy to master it. Of course you need the render tool mentioned above, and you need a graphics editor (like Gimp or Photoshop).
The idea is to change the sky image, since that's where the IBL is emitted from. This is the sky texture I used when rendering the picture above: A 4096 X 4096 image with 3 colours on a black background. With the enhance external brightness selected, no light sources are needed (although a combination will work fine), even when rendering with the moon icon. As long as the sky is textured and the objects you want to light up can "see" the sky, the objects will be lighted (and tinted) by the light emitted from the sky texture. The brighter the texture, the more light it emits.
I have made some renderings to show the effect.
COLOUR TESTS The person is facing southeast.
Still facing the same direction, the red light hits his face, and the blue light hits the back of his head, and the blinds. Why he is casting two shadows on the blinds, it takes someone with more knowledge than me to explain.
Here is another scene, where I'm showing the difference between traditional lighting and IBL – this time texturing the sky with a real image.
Notice that the base of the sky texture is a solid black. The size is dependent upon the Field of view-setting. The Field of view for this shot = 35.
It's of course a matter of preferences, but I find that using IBL adds a new dimension to the shot, and creates more depth and a nicer tint.
In this thread I made this premature proclamation:
Actually, for the upper part it's best to use a background colour that matches the sky exactly. The reason for this is that although radiosity is evidently not supported in Sunflow, there will be reflections from the sky on any reflective surface, and especially if there are reflecting water surfaces. So the right colour is very important.
Well, I live and learn. That was before I knew about the IBL possibility offered by Enkyonito.
I have made some tests where I have manipulated the upper part of a morning sky – replacing the original colour with a white solid. Here is a spherical image, showing the sky in 360:
Here is how it renders:
And here is how it renders with a darker upper part:
Here I'm using a toxic red sky to get a toxic red tint:
And then the same sky with a solid white upper part:
In my opinion, Image based lighting is adding a new dimension to SH3D.
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Well, the illustration was initially intended to be a comment on the US election - depicting the morning after – the hangover – whatever the outcome... until I started fiddling with the morning sky. Here is the first render, in the morning sun, with a normal morning sky ... somewhere near Amargosa Valley.
Joined: May 12, 2013
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Re: Image Based Lighting (IBL) – adding a new dimension to SH3D
@ Cec - you annoying you. Every time I think I have grasped some basic concepts and get ready for trying a more life-like rendering than I have tried so far, you come up with more interesting information. Interesting, but kind of daunting. At least I am now confused at a higher level. Please keep sharing your techniques. And beautiful (but disturbing) images.
If you ever were to write a mini-guide for SH3D rendering, I volunteer as a proofreader / guinea pig to ask stupid questions.
