Additive Density not showing past Exponent of -1

Deprecated Krakatoa 1.0 Beta Discussion
1

Hi guys, i just joined the beta (0.9.6) and i’m having a small problem.

I may have missed something somewhere, but following the basic guide in the “Additional refinements” section, i’ve set the Density exponent to -3.0 and nothing renders. Even at -2.0 i’m getting nothing, but at -1.0 it works. Switching back to volumetric works also, but additive shows nothing.



I don’t want to flag anything yet, as i’m sure it’s just my ignorance. :slight_smile:

_____________________

Martin Brennand

2

Martin,



The Exponent jumps by orders of magnitude. Additive Density is highly dependent on the particle count (while Volumetric Density takes into account the particle count and keeps a constant density). So if you see particles at -1 but none at -2, you should keep -1 and go down slowly with the Density value (it defaults to 5.0, so if you have 510^-1, you are using 0.5 density).



When you switch to -2, your density is 0.05 and that could be a jump too large for your particle count to add into something visible, so going down with 0.4, 0.3, 0.2, 0.1 etc. (0.4 = 410^-1 -> Density 4.0, Exponent -1) would be the real “fine-tuning”. You can of course enter 0 for Exponent and adjust the Density in the first field with any value step you want.

The Exponent was added so if you need a VERY large or VERY small number, you don’t have to enter numbers like 0.00000001 or 420000000.0 but can use scientific notation instead. Also, when you want to reduce or increase density by a whole order of magnitude, it is very easy to click the spinner arrows once.



Hope this helps…



Borislav “Bobo” Petrov

Technical Director 3D VFX

Frantic Films Winnipeg

3

Makes sense! Thanks Bobo.

Can this explanation or something like it be added to the tutorial in the documentation? I was just following along with the specific instructions when this occurred.

EDIT: Scratch that. I just read it in the next section. Apologies.


_____________________

Martin Brennand

4

Also read what is says in the group box in that section of the GUI (in the next build, the HINT will be underneath the Density controls at the right instead of the Light Pass Density at the left)…



:o)



Borislav “Bobo” Petrov

Technical Director 3D VFX

Frantic Films Winnipeg

5

Heh… thanks! I’m starting to get my head around it. The pieces are falling into place. :smiley:

_____________________

Martin Brennand