HELP! Daylight!

[portisgreg]

Hi all,

 

I'm working on a sun study using 3dsmax and Mental ray. I've mapped the building but left the site in a white material.

 

As you can see the materials are all burnt out/greyish and the shadows are too dark and unrealistic.

 

Any ideas how i can improve this?

 

Settings

 

I have a Daylight system, 'standard' skylight and sunlight.

 

Date time location - london - today.

 

Ray traced shadows

 

Multiplier 62.11

 

Logarithmic exposure control: brightness 65, contrast 50, midtones 1, physical scale 1500, exterior daylight.

 

MR Settings: GI enabled, photons 500, volumes 100, photon map rebuild, trace depth 5, 5, 5.

 

Avg GI photons per light 10000, GI multiplier 2.0, decay 2.0.

 

Final gather: samples 2000, filter 1, trace depth 5, max reflections 5, refractions 5, bounces 0.

 

Any help would be much appreciated!

 

Cheers

 

Greg

[Tommy Burns]

Hi

 

I had this problem myself and what caused it for me was the photons and FG.

What I was doing wrong was saving the photon and FG maps. When i changed settings of photon and FG it always seemed to use the first map settings and not update the changes. It was only when I unticked save maps and tweeked the FG and Photons settings did I get it to work. When it was right then I saved the FG and PH files. I'm not sure how the saving map settings work or how you get them to update. Maybe something to do with Read Only (FG Freeze) maybe somebody else could clarify this for us.

Hope this works let me know how you get on as I think this is a problem a lot of people will have.

 

Tommy

[pixelperfectg]

IMHO, you shouldn't use the standard daylight system with mental ray. Why? If you use GI, which you say you are, then you have no way of focusing the photons. They are being shot all over the place. With the mrSun (or a spotlight/direct light) you have the ability to properly focus your photons so that most of them actually hit something in your scene.

 

When I say "focus the photons", I'm referring to making sure your light source is properly aimed at the objects in your scene. Here's an image to help explain it a bit:

Although I'm using the mrSun as an example in this example you can also "focus" a mrSpotlight or target direct light by using the hotspot/beam & falloff/field settings.

 

Since you're not using the mrSun/mrSky, I assume you're using a pre max9 version? As such, I'd use a mrSpotlight for the sun, or if you aren't concerned with area shadows, use a direct light for the sun. Then add a regular skylight with a blueish tint.

 

Personally speaking, since this is an exterior, I'd just use FG with about 2 bounces, no GI.

[AJLynn]

I love photon focus. Is this a new mr3.5 feature? That used to only be in... finalRender?

[pixelperfectg]

Is this a new mr3.5 feature?

Kinda, it's really only an option on the mrSun. I should clarify that we aren't truly able to "focus" the photons when using any other light. By adjusting the hotspot/beam & falloff/field settings on regular lights it's focusing the light source which in turn controls the photon emission.

 

It's not the same with the mrSun photon target option. It allows you to actually focus the photons without affecting the focus/range of the light itself.

[AJLynn]

I don't know if this works (or is the efficient way) in mr, but my kludge for spotlight photon focus is 2 spotlights in the same place, one has the correct spread and its output set to N (which is what you actually want) and no photons; the other is tightly focused, has photons, output is N/100 and photon multiplier is N*100. Basically, one contributes only direct and the other contributes only photons.

[portisgreg]

Thanks for your replies guys.

 

I've used daylight system cos i need to animate a sun study and doing that with Mr spot would be too difficult.

 

I've attached the file if anyone has any other suggestions...

 

I had to compress it with winrar to get it small enough but had to name it .zip to get it to upload so if you manage to download it then rename to .rar then open.

 

Thanks

 

Greg

[pixelperfectg]

I've used daylight system cos i need to animate a sun study and doing that with Mr spot would be too difficult.

1. Turn off the daylight system light(s)

2. Add a mrSpotlight to the scene.

3. Use the align tool to place the mrspotlight in the same location as the daylight system sun.

4. Use the "select and link" button to link the mrspotlight to the animated daylight system.

[portisgreg]

Nice plan Batman!

 

Thanks.