Why do the clouds not block the sun?

Started by reck, September 15, 2007, 06:26:12 PM

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reck

I'm trying to create a sunset scene with some low level clouds. At the moment the clouds don't really block out the sun and the disc is still completely visible through the clouds. What setting do I need to alter to fix this? You can se what i'm talking about in pic1.

Also is it possible to make the sun look bright like it really does at sunset and also for the light to bleed through objects in front of it and the ground? see pic2 which is a photo, this is what I want to create in TG2 but with some clouds in front.



dhavalmistry

it is a known bug currently worked on...the workaround is to enable ray tracing....
"His blood-terragen level is 99.99%...he is definitely drunk on Terragen!"

reck


Will

The world is round... so you have to use spherical projection.

reck

I have enabled ray traced shadows in the cloud layer and also the atmosphere, it makes no difference.

reck

Yeah that second pic does look nice Will. It's just a photo I found on the internet that someone took. I only use that photo to demonstrate what i'm trying to achieve with the brightness and blooming/bleeding of the sun.

dhavalmistry

another workaround would be to disable the visible disk option in lighting tab....
"His blood-terragen level is 99.99%...he is definitely drunk on Terragen!"

reck

Yeah I tried that but then you can't see the sun, and the image is based on a sunset so it sort of defeats the object if I turn it off.

After messing around with it for a bit I think it's just a limitation with the show disc option. Hopfully this will be improved by the final. Also I hope there will be a way to bloom/bleed the light to make it more realistic.

Seth

totally agree... i tried to do an image based on the sun behind the clouds but the sun was always visble... and as reck said, if your pic i based on the sun it's not possible to disable the "visible disk" tab... :)

reck

I've finished rendering the image but it's not come out to good. It seems to be very hard to cover up the shape of the sun with clouds. As you can see in the image most of the clouds in front of the sun just make that part look a bit darker rather then breaking up the circle.

As it turns out what i'm more disappointed in is the fact the sun just looks like a white circle instead of blazing star. At low altitudes it seems very hard to make the sun look like a blinding light.

If anyone has a solution to this i'd love to know, but at the moment I can't get it to look like the photo in the first post.


Saurav

You can get that bloom/bleeding effect by outputting the render as an exr file and changing the exposure levels in Photoshop.

reck

Hi thanks for the tip, unfortunatly I don't have Photoshop or any other commerical paint software for that matter. All the images I create are pure TG2 images so I can only use the features that are available in TG2.

efflux

Cinepaint is a free app that does exr, if editing that could be a solution. I don't know about the clouds problem and I have never tried a scene like this but the way I look it is that the sun disk is really just a fake thing. The light is still streaming from one point so increasing the sun disk does not increase the area that the light is coming from hence you won't get a glowing ball. There is also a problem with the sun disk not being actually in line with the light source when you move away from position 0,0,0.

Sengin

Perhaps incresing the density of the clouds to ~10 (or even more) would solve your problem?

cyphyr

#14
Upping the cloud density to a higher value (depending on your scene but I used 10 in the image below) seems to work fine. One thing to note, again depending on your scene) is that if the cloud is "directly" in front of the sun then it will cast very dark shadows over your foreground, maybe what your looking for, maybe not. If not then you'll need to re-render the scene without the cloud and composite the two images together.
Richard
www.richardfraservfx.com
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