Sun control in blendigo.

Woodie · Post by **Woodie** » Mon Jun 30, 2008 11:56 am

I (for the first time) tried to setup0 a dusk scene, but came to the hoop. How you control the brightness of the sun? I always assumed that you just direct sun so it is very low above horizon, but it seam not to work for me. It is low but still very bright. Do I miss something?

Kram1032 · Post by **Kram1032** » Mon Jun 30, 2008 11:05 pm

The brightness of the sun is "correct". You can't control it except via lowering it down to the horizon. Instead, you need to adjust all your meshlights to a brighter value in order to be able to still see them...

Caronte · Post by **Caronte** » Tue Jul 01, 2008 12:20 am

You must adjust the angle of the sun, not her position

Woodie · Post by **Woodie** » Tue Jul 01, 2008 1:47 am

Kram1032 wrote:The brightness of the sun is "correct". You can't control it except via lowering it down to the horizon. Instead, you need to adjust all your meshlights to a brighter value in order to be able to still see them...

Wait a second, I know that sun brightness is constant, but I always thought that it behaves like in our world. It's getting darker in the evening (setting sun). To compensate brightness of the sun, my lamps would have to be very very strong (couple of thousands of watts). That would be strange. Are you sure that's how you do it?

Caronte wrote:You must adjust the angle of the sun, not her position

That is what I did.

Caronte · Post by **Caronte** » Tue Jul 01, 2008 7:01 am

Woodie wrote:That is what I did.

No, you did: "...except via lowering it down to the horizon."

That isn't correct, because you can put the sun whatever place on the scene, the only usable value is the angle (you must rotate it to get different hours of day)

Woodie · Post by **Woodie** » Tue Jul 01, 2008 12:27 pm

Caronte wrote:
Woodie wrote:That is what I did.
No, you did: "...except via lowering it down to the horizon."

That isn't correct, because you can put the sun whatever place on the scene, the only usable value is the angle (you must rotate it to get different hours of day)

Isn't that what is happening with the sun when you say it is low over horizon? Low above horizon mean (I can be wrong - English is not my native tongue) small angle between earth surface and line between you and sun.

Caronte · Post by **Caronte** » Tue Jul 01, 2008 8:58 pm

In you scene, try to change the Sun position and put it over the scene (without changing the angle)...

The result are exactly the same

Even more, if you leave the Sun in the same place (low over horizon) but changes the angle, your Sun no more appears just over the horizon

palawat · Post by **palawat** » Tue Jul 01, 2008 9:03 pm

Woodie,
Could you pls post your render? I'm not sure what king of brightness you want (or don't want).

Below is my test render using sun's angle quite close to yours.

Woodie · Post by **Woodie** » Wed Jul 02, 2008 12:55 am

Caronte wrote:In you scene, try to change the Sun position and put it over the scene (without changing the angle)...

The result are exactly the same

Even more, if you leave the Sun in the same place (low over horizon) but changes the angle, your Sun no more appears just over the horizon

Well I don't know. You can see sunset a bit longer on top of the mountain. Isn't indigo assuming that at z=0 you are at see level?

(I seriously don't know).

@ palawat
I will post something when I will come back home, but basically using Camera Tone Mapping I was getting scenes very bright @ ISO 100 F11 1/500s (EV=0) even when sun was below the horizon. Do I need to make huge sphere to simulate earth to get proper results?

palawat · Post by **palawat** » Wed Jul 02, 2008 2:14 am

Oh, I see. My last render was a Rienhard one.

For camera mapping, you might have to play with exposure and F-Stop. No huge sphere to simulate the earth required.

Pls know that I'm a noob myself and don't take my word for granted.

Woodie · Post by **Woodie** » Wed Jul 02, 2008 3:16 pm

OK. I finally got opportunity to prepare all materials.

Settings at noon.

result

Settings at sunset.

result

Settings at night (lights on)

result

At firs sight looks OK, but lets look closer: night, ISO100, F8 1/125s. Lets allow for i bit more light.

1/15s

Wait a minute. Anybody who is using camera for more than a minute knows that at this settings (night, ISO100, F8 1/15s) your frame schould be pure black. I even took my camera went outside to test it. Black (seriously black - that's why no screenshot). No nice blue moon shade.
So I took another step. Lets move the sun a bit up. Say one hour after sunset. Still should be night and black.

Settings:

result:

My eyes, my eyes.

. Something here is wrong. Is it something with my scene, blendigo or indigo? I don't know.
Any clues?

zsouthboy · Post by **zsouthboy** » Wed Jul 02, 2008 3:28 pm

Sun below horizon does not = night time, in indigo - there's no simulation of moonlight.

Woodie · Post by **Woodie** » Wed Jul 02, 2008 4:24 pm

Well, I know that. But why sun makes those renders so bright?

palawat · Post by **palawat** » Wed Jul 02, 2008 8:18 pm

Very interesting model I must say.

Can't wait to see your final render, with all the light, caustics from the water along with lighting condition.

Kram1032 · Post by **Kram1032** » Thu Jul 03, 2008 6:59 am

It is a limited model. It's not meant to be used for night. It never was and it might not ever will be.

For night, you can do:
- very extreme tonemapping with quite blue whitepoint
or (the more realistic but far slower way)
- true atmospherics + a moon model (even textured if you want) in the correct distance.

Also turbidity above, I think it was, 2.5 will give strange results. @ turbidity 40 for instance, the sky is green

Sun control in blendigo.

Sun control in blendigo.

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