Daylight IES Sun/SKy with bitmap sky background

[Ausmax]

Hello,

**Using Scanline Renderer daylight system

 

I have a bitmap sky that appears dimmed when I add a daylight IES Sun/Sky. It appears ok in the viewport but when I render it, dimmed in the scene. (I chose a bitmap because I need clouds).

My Daylight object excludes the sky bitmap so I don't see why the Sky bitmap is dimmed when I render it.

 

The only other thing I should say is that I have used a standard

omni light to illuminate the sky bitmap. When using the daylight system

can you use standard lights or should I have chosen a photometric light?

Does it make sense to use a photometric light for external illumination?

 

Thank you for any help you can give me on this matter.

Edited February 8, 2010 by Ausmax
further explaination of topic

[Peter M. Gruhn]

I think you're doin' it wrong.

 

Sounds like you have created geometry to put a material on (sky dome or some such). If so, you just don't need to, and it can cause trouble with other things.

 

You can just set a bitmap to be the scene background in the environment dialog (on the render menu or hit '8'). Put the same bitmap (instance) in a slot in the material editor to adjust mapping (screen, environment spherical etc.)

 

If you do need to have the texture on geometry then you don't need to illuminate it with a separate light source you can set the material to self-illuminated and let it shine out 100% no matter what else is happening in the scene.

 

If you aren't doing it with geometry and it is already the environment then no amount of shining light on it will do anything as there isn't anything to shine light on. The environment map is just "what do I show when there's nothing to show?" And the dimming is maybe caused by auto-exposure processing the background.

 

--------------

 

OK, I just reread your post and picked up on the daylight excluding the sky. So I'm pretty sure you do have actual geometry and not just a bitmap in the scene. So what I think is happening:

 

You have some geometry which is being lit by a weak light and the rest of the scene is being lit by THE SUN, which is pretty bright. In contrast with the sun, your omni is pretty wussy. You do have autoexposure on so the underlit sky comes out darker than stuff with THE FULL POWER OF THE SUN shining on them.

 

If you want to keep this rig (which I recommend against) then (I'm guessing this will work) the easy bet would be to increase the multiplier on the light shining on the sky. Try 64. Then try 10000 and try 2 if need be.

 

But you'd probably be better off to do as above re: either self illumination (don't) or environtment map (do).

 

I hope I got it!

[Ausmax]

I think you're doin' it wrong.

 

Sounds like you have created geometry to put a material on (sky dome or some such). If so, you just don't need to, and it can cause trouble with other things.

 

You can just set a bitmap to be the scene background in the environment dialog (on the render menu or hit '8'). Put the same bitmap (instance) in a slot in the material editor to adjust mapping (screen, environment spherical etc.)

 

If you do need to have the texture on geometry then you don't need to illuminate it with a separate light source you can set the material to self-illuminated and let it shine out 100% no matter what else is happening in the scene.

 

If you aren't doing it with geometry and it is already the environment then no amount of shining light on it will do anything as there isn't anything to shine light on. The environment map is just "what do I show when there's nothing to show?" And the dimming is maybe caused by auto-exposure processing the background.

 

--------------

 

OK, I just reread your post and picked up on the daylight excluding the sky. So I'm pretty sure you do have actual geometry and not just a bitmap in the scene. So what I think is happening:

 

You have some geometry which is being lit by a weak light and the rest of the scene is being lit by THE SUN, which is pretty bright. In contrast with the sun, your omni is pretty wussy. You do have autoexposure on so the underlit sky comes out darker than stuff with THE FULL POWER OF THE SUN shining on them.

 

If you want to keep this rig (which I recommend against) then (I'm guessing this will work) the easy bet would be to increase the multiplier on the light shining on the sky. Try 64. Then try 10000 and try 2 if need be.

 

But you'd probably be better off to do as above re: either self illumination (don't) or environtment map (do).

 

I hope I got it!

 

Hi Peter,

Yes I have been using a geometry based background.

I tried to adjust the intensity of the light assigned to light in the background bitmap of the sky. I see what you mean, I can improve the light but I should say that the colour is really washed out.

 

1.I am interested in what you were suggesting with the placing the bitmap into the environment slot. Could you explain further when you said

"Put the same bitmap (instance) in a slot in the material editor to adjust mapping (screen, environment spherical etc.)"

 

Pardon my ignorance but why do you need to adjust mapping on a background image?

 

2. Could you explain to me the difference between an ordinary environment map and a mr Physical sky map?

Edited February 8, 2010 by Ausmax
this comment has been posted twice

[Ausmax]

Hey Nigel,

 

You haven't mentioned which renderer you are using?

 

regards

Bri

 

Hi Brian,

3DS Max's scanline Render engine I think.

[Peter M. Gruhn]

I've got to go to bed and won't be in tomorrow really. If Nigel's in a hurry, anybody else want to tackle this?

 

Meanwhile, check the docs.

[Ausmax]

I fixed the washing out, dimming issue with the background sky.

It was a exposure control issue - I just set to Linear exposure control

thanks for your help - mr looks more complex - I will investigate

[Ausmax]

Ok, so my thoughts on using a rig is perhaps an old way of going about things? Mental Ray Daylight seems to be way better than the scanline renderer. mr backgrounds are completely different from the limitations of the scanline Background image solution (am I right??)

I feel like I am talking to myself on this thread - doesn't matter!! I will get there.

Cheers

Edited February 8, 2010 by Ausmax
missed detail

[Peter M. Gruhn]

Yeah, don't go with a physical rig for background. Use the environment background.

 

I'm not sure what you're saying about MR.