Lightworks lighting not behaving as expected.

[Anonymous]

I was working on a couple of 3D images today, and the first one (Northern Perspective) worked fine, but then I couldn't get the second one's (Southern Perspective) lighting to work the way I wanted. In trying to eliminate the problem, I ended up doing the first render again, to check that it all looked ok, and then I swung the view around to the other side and rendered that view, without touching anything else. You can see in the attached images, specifically in the circled areas, that the shadows behind the wall sticking out look correct in the first image, but not in the second. I have turned on all layers and searched each story for any Lamp objects that shouldn't be there, but the only Lamp objects were my sun and sky objects. So can anyone suggest what the problem might be? If it makes any difference, the horizontal boarded cladding is a Morph, but both 'Cast' and 'Received' are ticked under 'Morph Shadows'.

[Anonymous]

Southern Perspective

[Anonymous]

My Lightworks settings for the above images.

By the way, I forgot to mention that in the Southern Perspective there is also the dark shadow in the corner in the circled area, as if it is trying to work correctly, but it is the wall adjacent to the shadowed wall that is the problem.

[Karl Ottenstein]

The other shadows look as I would expect with a high ambient (sky) illumination and camera light.

But, your settings confuse me: why is the sun turned off and lamps turned on for a daytime exterior render? Also, turn the camera light off. It should almost never be on for exteriors - and rarely for interiors (it is a cheat for interiors, substituting for proper interior lighting).

[Anonymous]

Thanks for the tips Karl. I tried the northern perspective without the camera and lamps turned off, and sun turned on, and got decent results. And it did fix the problem at the south, but I didn't think the image was as realistic.

But I have to say your comment has confused me, as I thought the norm was to use sun and sky objects, as opposed to the built-in sun, for the reason that it is more realistic. I will attach a couple more images to show the difference.

[Anonymous]

This is the actual view I will be using, and this image is rendered with the Sun off and Lamps on, meaning the sun and sky objects are used. The lighting better differentiates the different surfaces, making it look more realistic, but it is unrealistic in that the sun is supposed to be coming from the west.

[Anonymous]

This image is rendered with the Sun on and Lamps off. It correctly shows shadows for a western sun, but everything in shadow comes out the same colour - look at the post supporting the carport roof, and the wall behind it. They are both the same material/surface, but they should be distinguished by the light.

So I guess the reason for pointing this out is that while the above settings do correct the problem, they are not really a solution because the original image looks better.

[David Maudlin]

benanna88 wrote:
But I have to say your comment has confused me, as I thought the norm was to use sun and sky objects, as opposed to the built-in sun, for the reason that it is more realistic.

You can use the LightWorks Environment > Sun: Realistic Sun rather than the Sun Objects (Lamps). Try playing with the LightWorks Effects > Light Sources > Sun and Ambient %s (they can be greater than 100%) to get a better result.

David

[Karl Ottenstein]

As David said, the realistic sun option typically replaces the sun object from earlier releases. It reads the sun position from the Sun Settings dialog - same as OpenGL shadows. The shadows look the same in both of your images... but perhaps you manually set the sun position in your sun object?

Your ambient is too low for the scene (background image)... and the sun is not warm enough (needs a bit of yellow) to match the warmth of the sun in your background image. (Some of that tonal adjustment is often more easily done in Photoshop in the end, to be honest, rather than repeated trial and error with the color of sunlight in AC.) As David suggests, boost your ambient %.

You will want to use Dwight's "under sun" technique to illuminate the bottom of the carport roof/ceiling as LW's ambient won't do anything there. (In AC 18, the CineRender engine has true Global Illumination and will bounce light off the ground and onto the ceiling - giving more realistic images way more easily.)

[Anonymous]

Thanks again to both of you for your help. I haven't had a chance to play around with this again until today, but I was quickly able to narrow down the original problem after turning Lamps back on to use an "under sun". I was getting really poor results again when I turned Lamps on, and so I turned the under sun right down, and then off, and then deleted all Lamps from the project, and found that I was still getting the strange lighting from the original southern perspective. I will attach a couple more images, the only difference between the two being the Lamps check box being ticked. It seems that Lightworks is remembering my past lamp settings and using them even when the lamp has been deleted, because you will notice how brightly lit the underside of the carport roof is, which is how it has been since I first set up the under sun, before I turned it right down.

So it seems to be a project specific bug, because I haven't noticed anything like this before, unless one of you can suggest a reason for this happening. And obviously I need to sort this issue out before I get the lighting levels right, because I can't use an under sun until then.

Thanks

Ben