External Lighting

[LukeC]

hey guys, sorry for yet another question

 

Im having a few issues with outdoor lighting. The scene is about 3km x 2km roughly and Im trying to light it with Daylight system. See I thought what i had to do was put in a daylight system, set the exposure control to logarithmic, calculate the radiosity and then im set.

 

Thing is, the automatic exposure control looks much better then logarithmic but a bit too dark, not realistic enough, and the logarithmic control looks really washed out and the colours look really strange.

 

From previous experience, when i set a daylight system with automatic control, everything goes practicly white and logarithmic corrects this but this isnt the case in this.

 

Would it have anything to do with the units being setup wrong and its calculating it all wrong or anything to that effect?

 

any help would be greatly appreciated

 

cheers

Luke

[Bugga_Guy]

Luke

 

Make sure you have the "exterior daylight" dialog box checked in the environemnt and effects tab.

[LukeC]

Bugga_Guy, thats the thing. it already is.

 

here is some renders with the scene with the daylight and render settings as standard, no changes and radiosity at 85% with no refine iterations and global subdivisions disabled.

 

Just to note, I rendered each image with and without radiosity at the forementioned settings, and they both look exactly the same.

 

1st image - logarithmic

2nd image - automatic

[Tim Nelson]

I think the automatic version looks great! The underside of the bridge looks like the only part thats a little underexposed, but there's probably an easy way to boost that. As a Vray user, I don't know what you could use to do that, but I think its looking great.

[LukeC]

hmm yeh see I dont really think so. I spose it looks ok in that photo but overall it really is terrible.

 

Just wish there were a list of settings somewhere for lighting large outdoor scenes realisticly as i really am stuck as to why this scene wont light properly

[leed]

I do not use viz, but what is the angle of the sun-light. it looks as though it is directly above, which will make the image look flat.

you need some smooth shading attributes on some of the land form elements. it looks just a bit rigid.

 

Angle the sun and render some more.

 

hope this helps

 

lee

[STRAT]

why not completely lower the direct lighting and rely more on some IBL? should give a better feel to the model

[Buffalo Bills]

Luke C,

 

I've experienced the same results as you have with the Logarithmic exposure control. Like others have said you might want to change the angle of the daylight to get some of the contours of your site to read better. With the map you are using for your base, you might want to try to beef up the contrast and brightness either through the map dialog box in Viz, or through photoshop. Also, you might also want to try to turn on your refine iterations and subdivision settings. With those turned on will smooth out the light calculations so they are not so flat, plus it might allow light to bounce under the overpasses and lighten those areas up. It will add a little more time to your calculation time, but you might get better lighting results. But overall it is looking pretty good for what you have so far!

[ShaunDon]

Hey Luke --

 

I'd recommend using a fakiosity light ring rather than VIZ radiosity when dealing with exteriors, especially on larger site areas. I've had a lot of success myself, and even used them in VRay for awhile until I was ballsy enough to do animations with its irradiance engine.

 

I've attached the ring I created for an animation eight months ago. I was really trying to optimize it for frame speed, so you might find the shadow map settings are a little too low for a still image. Each ring level is instanced, the lowest level casting no shadows as it should be underground.

 

I'd be more inclined to use this to get your soft skylight shadows and then hit it with a strong direct light, lower to the ground like Lee said.

 

Good luck!

 

Shaun

[LukeC]

That was really helpful. Ill just point out a few things before i make some changes today and get back to you later this afternoon.

 

Firstly, unfortunately I cant change the light, the reason im using a sunlight is because of its location and time settings as I am actually going to camera match the design onto some live footage and still images. I spose in that respect it eliminates the point about smoothing out the landscape, although I will be using the terain to catch shadows for camera matching.

 

The reason the image looks a bit off is because of the way its rendering in viz, its actually a very high quality image im using so doesnt need any adjusting (its 10 000x 20 000 pixels although im using the 5 000 by 10 000 image in that render)

 

anyway im going to have a play around today with the comments given here and ill get back on how it goes.

 

thanks for the good response.

 

oh one last thing, if anyone knows why the logarithmic exposure control sometimes makes everything go a little strange, can you let me know and tell me what im doing wrong.

 

cheers

Luke

[Bugga_Guy]

Sorry if this sounds stupid but is the model to scale? did you run a high inital quiality in the radioisty dialog box.

 

you can play aroung with brightness and contras and mid tones and physical scale (all trial and error unfortunatly)

 

 

But still the one image with automatic still turned out fairly pretty good.

[LukeC]

sorry about the late reply but yeh the model is to scale, ive checked that.

 

The model is in metres and the sunlight has a intensity of 99239.477lx. Now im not sure if this is meant to be correct or not, but thast my current settings. I have also noticed that i cant adjust that number at all. I can type in a new intensity but it goes back to 99239.477.

[LukeC]

Also, just out of curiosity,

 

would a 3rd party renderer be useful in this situation. Is there any suited well to large outdoor scenes or are they more geared towards indoor architectural style renderings?