Im trying to produce a sandman at the moment. The current workflow was just to use a PRT Volume on the sandman mesh and then I have used fumeFX to drive a layer of sand falling off. I think my boss wants more of an internal movement, pretty much like a noise pattern with an animated phase but following the sandmans geometry. So I created this effect using a simple Pflow setup with a position born and using density by grayscale and animated phase. the particles are spawned between 0 and 100 and have 1 frame life. The update time is just crazy and thats with under a million particles then trying to save to a PRT sequence is 5 mins a frame or so.
Just wondering if anyone would have a better approach or has done a recent sandman setup and maybe have some pointers I was thinking maybe I could save 1 frame of the PRT Volume and maybe effect the colour using a KCM and have it appear like the particles are shifting around the body. Not quite sure yet as just started!
Since sand is pretty much opaque after a very low depth, you probably don’t need the WHOLE body inside to have moving particles. So I would suggest the following approach (but I haven’t tested it, so not sure how well it would work).
*Create a PRT Volume from the T-Pose of the character.
*Set the PRT Volume to “Seed In Surface Shell” with “Shell Start” 0.0 and SOME Thickness (the exact value will require some tweaking).
*Save this PRT Volume to a single PRT file - this will be your “Sand Skin”
*Create another PRT Volume from the character and set the Seed In Surface Shell to start at the Thinkness value of the previous PRT Volume, and have a higher Thickness.
*This PRT Volume will be updated dynamically as the character moves and will be just a “filler”. You can tweak this Thickness to produce enough particles to block all light and make the body look solid. You could even set the Thickness so high that the whole body is filled with particles, but it might be just a waste of resources if you never see deep enough.
*Create a PRT Loader and get the single PRT file saved from the first PRT Volume. Check “Load Single Frame Only”. Add a Krakatoa Skin Wrap to it and pick the character. You MUST have your character in T-pose on one frame (say, frame 0) as a reference frame for the Skin Wrap to deform against. Now your PRT frame will be following the character’s surface. This can be quite slow, but you will get particles that actually stick to the moving body instead of coming in and out of existence as the mesh moves through space.
*You could try to animate the outer “Sand Skin” now using KCM or Noise Modifier to shift the particles around.
*You could then emit particles from the mesh surface using PFlow to get the falling sand.
With this setup, you get a dense volume of particles where the core is pure PRT Volume that is very fast and is just used to block light, plus a thin layer of surface particles that can be animated dynamically and follow the body animation, plus dynamic particles from PFlow to fall off.
Ah thanks Bobo… that sounds a very interesting setup that may work, shall give it ago.
I really didnt notice that you could give the volume a thinkness so I have been rendering the whole mesh as a volume and thus creating 34 million particles on one frame to get a very dense mesh as they wanted the character to be a mix between a sandman and a ‘mud’ type texture so theres a lot of definition in the mesh… I think your approach could work so I will let you know how it goes
Here is a quick video of what I did so far… obviously only using 1 frame rendered out for the body which is 34 million particles:
If you can get away with just a dynamic PRT Volume with enough thickness to block all the light but hollow inside to save you particles, you might not need the whole Krakatoa Skin Wrap setup which is cool but generally slow. If the character is moving, particles will be revealed as it moves through space, but that might actually look like “moving particles” anyway…
You could try to wire a KCM with a Noise input to shift the particles over time to make them move “alive”…
Luckily I dont have to do a whole moving charater… the sandman is going to form from a pile of sand which I have covered I think The only bit where there is going to be movement is a close up shot on the face so I could just wrap the head particles in another scene I like your idea on the KCM noise but I shall have a look in the morning as I am not too clued up on KCM just yet (had a little go with it) and I have to go home and sleep hehe…Really appreciate your help Bobo, as always!
Hey bobo… any idea why the saved particles always say no ID channel available even though it is specified in the channels to be exported? I am saving a single frame from a PRT_Volume and then loading into a PRT_Loader and then trying to load the same Loader into Pflow.
PRT Volume objects don’t have an ID channel to save unless you create one. The simplest approach is to create a KCM that writes the Index into the ID channel (which is what the PFlow op is doing, but warning you about). The reason this is not automatic is that the Index is not a valid ID when using anything other than a single frame.
You can use the Krakatoa Particle Data Viewer to determine what exactly is going on in your particles. Its a spreadsheet like window that shows all the channels and their values for your particles. Just select the PRT Loader and select “Launch the Particle Data Viewer Utility …” from the Krakatoa menu bar.
nice test so far, seems like if you cranked your particles up even higher for the falling sand you would land in a good density, still retaining enough
grain to feel like sand but with more refinement to make the areas that overlap feel like a fine dust.
The only bit where there is going to be movement is a close up shot on the face so I could just wrap the head particles in another scene 