CLOUD SCRIPT THREAD
See my vimeo tutorial on the Script here:
Dark Scarab did a nice tutorial on how to use the cloud generator(it’s somewhat sparse, but for those that do not like my vimeo tuts here’s a written one):
Also another tutorial on the script here making a tornado:
Here are some clouds animated:
Here is a Billboard Animateable Cloud Tutorial:
Notes about the script:
Be aware that some things are created in memory that I cannot delete. I tried to use commands like main.materials.remove to clean up memory after degenerate, but it only crashes blender so degenerate leaves lots of junk in the memory of your file that will eat into your file size, so degenerate sparingly.
As of 28315 Script now included with BLENDER!
No more installing etc.
Just go to preferences AddOns and enable the script! The version included is my latest and degenerate now works properly so have fun!
OK, so I’ve spent quite a few hours working volumetrics because I REALLY want clouds and thought I’d post what I have.
Here’s a tutorial I made on somewhat how to do it with nodes…
And here is the fairly old volume point density tutorial
And here is a quick flythrough:
Notes about how to do volumes:
Here are some general notes about volumes from Matt Ebb (the creator of volumes)
Anyway, the main thing to realise with this stuff is that it’s ‘physically based’. That is, it works internally based on physical principles of how light works in reality. So, it’s important to remember that in rendering, it’s all about light, and the final picture you get (just like in a real world camera) is just the resulting light that’s made its way through the scene and into the lens. That light can be emitted from a light source like a lamp, or coming through/from the sky, or being reflected off a solid object. In physical terms, there’s no difference between light that has reflected off an object (eg. the resulting color coming to the camera after a solid object has been shaded) vs the light being emitted from a lamp, it’s all just light.
When you think about it like this, there’s not really such a thing as ‘transparency’, its more like ‘how much light is transmitted through the volume’ - i.e if lots of light passes through from behind, its transparent, but if the volume blocks out lots of light from behind, it becomes opaque. But to keep this physically consistent, this doesn’t just govern ‘the light coming from behind’ (i.e. transparency) but also the way that the volume reacts to light that’s coming into the volume from light sources. This must be treated consistently in order to get realistic results.
One other disclaimer I should add is that (i regret) that the system has some problems atm that may not be fixed soon. When I merged this code into blender 2.5, the plan was that we would have a new shading system, implemented during durian, for the 2.5 release. The current shading system in blender is really nasty ancient code, and it’s not very well set up for more sophisticated stuff like volumes, so there are several issues such as volumes interacting with refracting/reflecting solid objects that can have problems, among other things too.
Some of this i was able to hack around with dodgy workarounds, but some of it is just really difficult in the current architecture. I didn’t think (and still don’t) it was worth my time and frustration spending a lot of time making even more dirty hacks to try and get it to ‘kind of work’ especially with a new shading system around the corner (bmesh syndrome!), so I’ve ignored some of those things. But now it seems we have no new shading system, and are a bit stuck with what we have for the time being. So unfortunately the volume rendering isn’t up to the standard of quality that I really hoped it would be, which i’m unhappy about, but there’s not a lot I can do about it right now from a practical standpoint
So, with all that said and in mind, this page might be a bit more understandable: http://wiki.blender.org/index.php/Us…olumeRendering
and also for some more background, you can read here too: http://mke3.net/weblog/volume-shading-updates
In blender now, ‘transmission’ is a kind of inverse. Transmission defines the colour (and intensity) of the remaining light after it has entered, and then been absorbed or scattered out of the volume. So in a sense you’re indirectly controlling how much light gets lost, by defining what the remainder should be. The reason it’s done like this is mainly because it’s more intuitive - you’re controlling how the end result should look (eg. ‘blue’) rather than specifying the colour of light that gets lost (orange) that would leave your final result that is blue.
Reflectance is a non-physical parameter i added, which is an exception to all that previous stuff i wrote above It’s a bit of a multiplier/tweak to let you control the colour/intensity of the reflected light (i.e. the light heading out of the volume and towards the camera) easily. it lets you do unphysical things like if your turn it up high, it will mean that more light is heading out of the volume than what entered it (since it’s scaling up the amount of light that gets reflected). This is un-physical, but can be useful if needed, though it’s better to use the non-physical stuff as a last resort after working with the other settings.
The texture stack is how you control volumes, the graphic below maps how the texture parameters to the actual material paramters:
These are my definitions from trial and error (not correct! but possibly useful)
Density:Where the volume is.
Scattering: How whispy the volume is 0=really faint, 10 = absorbs a ton of light
Asymmetry: How effective the Scattering is (0=scattering is really whispy even all the way to 10) as you go higher material gets really black and scattering gets more potent. Also effects how much volumes glow when backlit.
Emission:Make the material not black anymore.
Reflection: Leave at one because dropping it lower makes material black and higher is warned against. (haven’t played with this one too much)
Resolution: How accurate the shadows are. Lower resolution puts the shadows in the wrong areas and looks weird.
Step Size: How Pixelated the volume is. If this number is too large you will get weird star shaped spots in the volume.
Ok, I’m sure Matt Ebb is going to shoot me for the above definitions, but I don’t have all his technical knowledge and I want to make pretty pictures and these help me do it.:o Please comment and Correct me… Anybody?
Here’s more renders…