hmmmh?

Started by j meyer, October 28, 2007, 04:45:13 PM

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Mr_Lamppost

#60
I have just been experimenting with the scene I posted tonight on the other thread.  Working on basically the same thing in two places at once is going to be confusing for anybody reading this later on.  ;) ;D

http://forums.planetside.co.uk/index.php?topic=3093.new#new



The rotate Y vector looks like it gives the biggest variation in colour (Not properly tested). :-\  I switched to highly distorted Perlin ridges for the nebula and am getting loads of those squares showed up in some of the previous renders.  This is probably related to the Acceleration Cache setting but I don't think I am going to get the effect I am after using rotate vector  so will try something else


*** EDIT *** The squares are definitely down to the Acceleration Cache setting  *** /EDIT ***
Smoke me a kipper I'll be back for breakfast.

j meyer

I will try to rerender the one with the squares with other
Acceleration Cache settings then later today.
Looking forward to what you'll come up with.


j meyer

It worked for me too,thanks Mr.L..

As for the dark line i disabled the sphere and set the
planet size to zero to be sure that there are no shadows
casted by objects,then i disabled the atmosphere and
its cloud layer,but the line was still there.So finally i
unchecked shadows of atmosphere and got rid of that
line,but....see attached picture.
Still no idea what that is.

Mr_Lamppost

I sometimes get those dark lines in normal cirrus clouds when the sun is on or just below the horizon.  They are not always visible I guess a lot depends on the other settings.  There is one in the original nebula test I made.

Without the shadows the cloud is going to be fully illuminated all over, not tested but try lowering the density and see if you get your bright colours back.

I am probably not going to get the chance to do any TG for a couple of days  :(
Smoke me a kipper I'll be back for breakfast.

j meyer

Lowering and upping the density gives you slightly better
results,the best results i got by unchecking secondary for
the 3d cloud layer or for both cloud layers,but there's always
some loss.
At the moment i assume it could be the terminator of the
cloud sphere or at least something like a terminator.

Matt

Quote from: j meyer on January 18, 2008, 10:49:40 AM
Lowering and upping the density gives you slightly better
results,the best results i got by unchecking secondary for
the 3d cloud layer or for both cloud layers,but there's always
some loss.
At the moment i assume it could be the terminator of the
cloud sphere or at least something like a terminator.

That's exactly what it is. If you use 3D clouds the terminator is usually less noticeable, although it still depends on the depth of the cloud layer and the shapes and density of the clouds. With 2D clouds it's very difficult to avoid this line at the terminator.

Matt
Just because milk is white doesn't mean that clouds are made of milk.

j meyer

 ;D Thank you Matt!Good to know. ;D

Mr_Lamppost

Terminator.  That's the word I was wanting last time Doh  :-[

I have been working on some other things recently, looked at the sky and got inspired   ::) 

Here is my latest test and to be honest I think this volumetric nebula idea may be dead in the water.  :( :(    The cloud sphere is pushed out to e+09m and is e+07m thick   I used the "Halo" built vector technique to give it colour and it works OK in places but over all is less than satisfactory.  The terminator is clearly visible and there is a definite difference in the way the nebula is illuminated either side. 

Unless someone knows how to Freak the settings I doubt it is possible to achieve the effect we are after.  This is a perfectly reasonable limitation as TG is intended to simulate landscapes  ;)  The way light is scattered by clouds is exactly that; light scattered by water vapour, what these nebulas need is scattering based on gas.  Years ago I experimented on something similar using POV-Ray, which has a wider variety of scattering models to choose from.  Has anybody experimented with Cloud Colour and Scattering Colour?
Smoke me a kipper I'll be back for breakfast.

Matt

#68
With those settings the depth is only hundredth of the distance to the nebula. To me it seems unrealistic to have the view filled by a nebula when the nebula is contained to such a thin shell. I would try something like altitude 1e8, depth 1e8 (i.e. about the same depth as the distance).  This should avoid terminator issues and also avoid the flat look that the clouds have in your image.

Matt
Just because milk is white doesn't mean that clouds are made of milk.

j meyer

#69
In the last few images i used a mix of cloud color,scattering
color and the vector coloring,so a start has been made,but
as always more tests are required. ::) ;)
Edit:I didn't mention earlier,'cause first i thought that the
normal cloud coloring would be overridden by the vector
coloring.

As for the thick cloud layer, believe it or not,that's almost
exactly what i was going to try next.As soon as possible,that is. ;D

Mr_Lamppost

Quite right Matt.  Thin shell of cloud, not one of my better days  ??? I had better go to the bottom of the class then.

Here is the test again using 1e+08 for distance and thickness,  I had to lower the density quite a lot.  Don't expect a nebula to render fast, I only used 256 samples for this test and that was bad enough.

The terminator and lighting problems have gone, which is what should have happened the first time.
Smoke me a kipper I'll be back for breakfast.

rcallicotte

Looks very cool.

What "depth" and what "distance" did you change?
So this is Disney World.  Can we live here?

j meyer

Nice result,seems you're getting there. ;D

Mr_Lamppost

I had intended to work on this tonight, I got distracted: see posts elsewhere   :)

Settings: e+8  and e+ 8 as Matt suggested; density something like e-5.  (Sorry can't check as I have a rreder on). 
Smoke me a kipper I'll be back for breakfast.

j meyer

Still not where i want it,but hopefully a step forward.