Finally finally finally, after having been on the beta a while back (ages as it feels ) we did buy a set of licenses finally, so here i am back in business and ready to go all particular
After installing and playing with some premade flows i created knowing that the lics should arrive soon (and beeing in production already of course ) i realised a strange
difference in vfb brightness and the final output files. It seems that Krakatoa is not respecting Gamma/LUT settings (or the max vfb is double correcting ? without real krakatoa
experienced itâs hard to tell wich is correct).
As we work in linear workflow using VRay usually any input on this issue would be very welcome. For now iâll add a warning to the GUI macro i guess, but it would be very
appreacieted if anyone had any more insightful input on that issueâŚmore to come soonâŚrest assured
I am looking into creating custom âRenderelementsâ like velocity and alike. Now it seems pretty straightforward to me
to extend the Color by speed example to reflect particleâs velocity. What i would want tho would be screenspace velocity.
Before diving into the depths of PFlow and its MXS interface iâd like to ask if thatâs really possible at all ?
I GUESS i would have to take the particleâs position + its speed and mangle it through the current viewâs matrix.
so in short iâd like to know if this is possible at all and if i am on the right track before diving into it for hours.
I did a shot where I did a custom control of the specular/diffuse function. Box#3 made it quite simple. In your case you donât need the light, just the camera, the particle position, and the particle speed.
As to the brightness, why not just render out linear float? Krakatoa is EXTREMELY picky when it comes to lighting and shadow, and changes in particle density can have a huge effect on those. Best to render linear float and correct it in post.
Well from VRay we do render to linear float. I was wondering if krakatoa does linear float if Gamma/LUT is set to 2.2 ?
It uses the MaxVFB tho and the Max VFB automatically gamma-corrects if Gamma/LUT is turned on. So i dont see
what i am rendering. Am pretty sure i got something set up wrong hence i asked.
Thanks a lot for the input on velocity, so am ready to dive in
Having thought a little about the first question (while not having started working on it) an additional question arose.
How would i make sure that a correct absolute float value is used when the density is changing them so much. Is there
any way at all ? i assume iâd render without lighting and shadows, but the density alone changes the brightness a lot
and would hence act as a multiplier. On a sidenote i was wondering if multiplying the speed vector with the current
view transform matrix wouldnt give screenspace speed ? or am i off there ?
Krakatoa does linear float. Itâs something we tested a lot in the beta, and use all the time. Thereâs no setting for it, itâs the default. I wouldnât worry about the vfb much, we never use the renders straight out of Krakatoa, and weâre always checking values with the eyedropper.
If you render with very high density, and with nearest neighbor sampling, and without lighting, you will see the the per particle colors, but thatâs assuming youâre mapping the particles to voxels 1:1. Not sure how useful that would be. Better to have âcorrectâ colors and âcorrectâ density and âcorrectâ lighting and then youâll get âcorrectâ renders. Krakatoa can only handle the last 2, not the first 2, so youâd be on your own for that.
) we did buy a set of licenses finally, so here i am back in business and ready to go all particular 
) i realised a strange
