When wanting a realistic sky . . .

[Dave Buckley]

do you guys tend to add the sky in the 3d package such as using a sky dome??? If you do then do you use a high res bitmap or a hdri so that the lighting matches also???

If you just add the sky in post then do you use hdri's or again high res bitmaps???

Just wondering what techniques people use to get to a good looking sky replacement, that fits with the lighting and reflections etc???

In other words, i want it to look as real as possible?

If i was going for extreme realism i would take a guess that the sky used for the replacement would also be used for the lighting in the 3d package??

Is this right

[Joel C.]

If you want realistic lighting and appearance, I'd go with HDRI. It does both. That's what it's designed for.

Having said that, it's not super-hard to take a nice spherical (or hemispherical) sky shot (non-HDRI), map it to a sphere, find the sun and put a light source in the exact centre of the sun in the photo. Your lights and shadows should be spot-on then.

[Dave Buckley]

when using hdri and showing sky in the render? would you still need to map the hdri to a hemisphere???

[Tom Livings]

If this is for a still then do it in post. Make sure you render to a format that stores the alpha channel then just drop in your sky and tweak as necessary.

[Claudio Branch]

I would be judicious about using an HDR for the actual background image. It can be done, but you will want to use a really high quality/hi-res image.

For stills, I like to take my own photographs for the final background and use the HDR for it's light contribution and/or its presence in any reflective surfaces. For animations though, you cannot use this approach...

[James Burrell]

I use a sky dome for reflections and make it invisible to the camera when rendering, then plonk in a sky in post to make sure its just right.

[Dave Buckley]

so if it was for an animation what approach would you take.

[Tom Livings]

Ive done a few different things and been happy with them. vray sky environment works well. So does HDRI. The sky is less important with animation as long as the camera work and composition (direction) of the movie is good. Image focus can be directed by the movie maker and so the sky is less of an issue. In a still the eye drifts all over the image and everything gets a close examination.

[Dave Buckley]

all i want really is a realistic sky in stills and animations that looks as natural as possible, so i just thought hdri would be the way forward. The thing with adding the sky in post is that it takes ages finding a sky to suit the initial lighting solution, whereas with a hdri this is eliminated straight away as the lighting instantly matches the sky right?

[Tom Livings]

Well yes, but why accept a generic solution when you can have complete control? HDRI skies are problematic because of resolution. A lower res file renders quicker whilst a high res looks better. Now you can put one in the GI slot and one to override the background, but you're still tying yourself to one image to solve 2 issues (lighting and sky). I think the best solution is
1: light the scene in a way that makes the buildings look beautiful.
2: put in beautiful sky that matches lighting.
There's no right way and I dont know your workflow and deadlines. But the above is my method.