PDA

View Full Version : Really unusual lighting wanted!



starbase1
05-04-2019, 03:10 PM
Here's an odd one. I'm doing things with a high resolution displacement mapped moon model. All nice and accurate.

One of the bad things though is that, as with the real Moon, there are no craters visible except near the terminator, where the sun shines down at a very shallow angle.

And I'd like them to show everywhere. I got a partial result by blending one view lit from the left and one from the right, but I'd really like something where every segment is lit at the same shallow angle, and I'd like to do it without heavy photoshop work, as that would be a pain to animate.

So, any thoughts on how to illuminate every polygon from the same direction relative to the polygon?

Nick

lardbros
05-04-2019, 03:41 PM
My initial thought is crazy, and not sure if it'd work or not but:

How about unwrapping the actual moon mesh, so it lays flat. Like UV unwrapped, but the actual mesh. You could do it as a morph target.

Then light the unwrapped sphere, using a directional light. Then bake the shadows as a map. Then multiply that shadow buffer into the material of the spherical moon.

Does that make any sense? :)

Dan Ritchie
05-04-2019, 03:59 PM
A normal map is basically an emboss convolution, but in 3 color channels. Using a grayscale version of your normal map as a color map as well should do the job, I would think. Does that make sense?

starbase1
05-04-2019, 04:03 PM
Thanks Lardbros, Yes! That sounds like a really good solution! Given the nature of the lighting I was expecting to end up baking it anyway.
Thank You!

I'd had some vague thoughts about building directional light baffles that would be visible to rays and not the camera, but could not think of a practical way of doing that.

starbase1
05-04-2019, 04:05 PM
Dan - it's a displacement map - I see what you are getting at I think, but I really like the unwrap idea.

Thanks for the help though.

lardbros
05-04-2019, 04:21 PM
Actually, Dan's suggestion might be easier.

If I'm understanding what he means, you could take just the blue (or green, or red) channel of a normal map, and then as its greyscale, use it to multiply over the top of your colour.

RebelHill
05-04-2019, 06:16 PM
The ol spinning light trick?

starbase1
05-05-2019, 02:57 AM
Aha! Map building seems to have worked nicely.

starbase1
05-05-2019, 03:16 AM
And a render of the resulting map wrapped.

XswampyX
05-05-2019, 04:12 AM
And a render of the resulting map wrapped.

I don't like it at all. :hey:
It looks like a render from Lw 5 done by somebody who doesn't know what they are doing.

Sorry for being so blunt! :D

And I'm not saying you don't know what you are doing.

Edit :-

Just light it like any object.

144900

lardbros
05-05-2019, 05:48 AM
Glad it worked :) but...

I kind of disregarded the reason behind why you wanted this in the first place. :)

Why do you want it like that?

starbase1
05-05-2019, 06:14 AM
Well, I'm looking for a way to show craters across the whole globe, rather than just along the terminator. This makes it possible to directly compare cratering on different parts of the Moon knowing that other factors are the same.

I'm already getting results - for example, it has become clear to me that the Aitken basin is not just a depression, but also has MUCH lower relief on the crater walls.

I can also see value in using it for maps, again showing all the craters.

lardbros
05-05-2019, 06:25 AM
Ah, so more of a "visual research" type thing? That's cool :)

peebeearr
05-05-2019, 08:33 AM
Well, I'm looking for a way to show craters across the whole globe, rather than just along the terminator. This makes it possible to directly compare cratering on different parts of the Moon knowing that other factors are the same.

I'm already getting results - for example, it has become clear to me that the Aitken basin is not just a depression, but also has MUCH lower relief on the crater walls.

I can also see value in using it for maps, again showing all the craters.

Why not zoom in on certain areas and leave the lighting as realistic as possible? I created a displaced moon surface and had a ball going all over the place with it. If you want to emphasise a certain feature it is better to zoom in on those areas.
144901

Don't forget to zoom in on the image :-)

starbase1
05-05-2019, 11:49 AM
I already have a very high res realistic Moon, what I want to do is see features on different parts of the Moon >>under the same lighting conditions<<.

For another example take a look at the result I pasted earlier. By showing all the craters, you can really see the long chains of craters radiating away from Mare Orientale, (slightly below and right of the centre).

lardbros
05-05-2019, 04:52 PM
I hope you share whatever animation it is you're working on with this. Would be interested in seeing the end result :)