fastsss2 flythrough mode

[super gnu]

is this maya only?! i dont see it in the documentation or in the material for max.

[super gnu]

anyone? im being asked to do a flyover of a large sss2 model in a scene imported from maya. client has asked if i have vray 3 "as it had a nice flythrough mode for sss2"

however it seems in max , it doesnt.

[joconnell]

If the model isn't moving you can definitely cache to file? In the options tab there's a prepass section where you can cache a lighting result to file and it'll use it for future frames. The only thing of note is that the cache is locked to world space, not to the model itself, so even if the model doesn't deform but moves in position, the cache won't move with it. If it's a totally static model though, you're safe.

[super gnu]

yes but unless i missed something, in max we only have a per-frame prepass, and "from file" to load the solution per-frame.. this means any variance between frames lead to flickering.

apparently in maya you have another option for calculating a single flythrough prepass, in much the same way you can calculate an imap for a whole camera path. thus eliminating any blotchy shimmering.

from the vray for maya help page:

Prepass mode - this parameter is similar to the Mode parameter of the irradiance map and controls the way V-Ray handles the illumination map for the subsurface scattering
*new map every frame - a new map will be calculated for every frame of the animation and then discarded after rendering
*save every frame - a new map will be calculated and saved on the hard drive for every frame of the animation
*load map every frame - V-Ray will look for and load a previously saved illumination map for each frame of the animation
***save/load fly through map - V-Ray will create/load a single illumination map for all frames of the animation when only the camera is moving***

[joconnell]

So, if anything we're lacking the save every frame and load map every frame options, but what we do have is the prepass mode "single frame (autosave)". I've just done a tiny test here where I've made a box and a vray light, put on an sss2 material and set it to use prepass based illumination for the multiple scattering. In the options section I set the prepass mode to single frame (autosave) and set an output file name. I did a single frame render where my sss worked fine, then I set the prepass mode to from file. It still had the path to the prepass filename set. I then turned off my light in the scene to see if the sss would work and it looked the exact same as the render with the light on. I also rotated around the model to check if the sss file was view dependent like an irradiance map cache from a camera view, but it's not - the sss was calculated all the way through the model.

[super gnu]

erm.. no we are missing the "save/load flythrough map" option. its present in maya, but not in max.

"new map every frame " is equivalent to "single frame" in max

"save every frame" is equivalent to "single frame (autosave)" in max

and "load map every frame" is equivalent to "from file" in max.

To be honest ive not tested any significant models with sss2 and animation (even with just the camera moving) so i dont know how critical it will be. but i do know that in maya you can cache a range of frames into a static sss solution, and my client will be using this feature.. i will not be able to..

if , as you say the sss cache isnt view dependent (seems odd to me this) then i can maybe get away with doing a single cache for a point of view that incorporates the whole model at sufficiently high res (its a city) then fly over it, but since its an interpolated effect, it will be hard to get enough detail all over the model from a single frame calculation, and if i do a fresh cache for each frame (or dont use caching) then i have a good chance of getting shimmering.

[vlado]

Hm, it looks like this is indeed missing from the 3ds Max version. Will make a note to add it. How soon do you need this?

The samples in the sss illumination map are view-independent, but they are generated only on the parts of the object that the camera sees (same as the irradiance map for GI).

Best regards,
Vlado

[super gnu]

well im due to start the job in 4 weeks, so not super urgent but it will be a bit problematic to accept the job if its not included by then.

thanks Vlado.

[joconnell]

erm.. no we are missing the "save/load flythrough map" option. its present in maya, but not in max.

"new map every frame " is equivalent to "single frame" in max

"save every frame" is equivalent to "single frame (autosave)" in max

and "load map every frame" is equivalent to "from file" in max.

To be honest ive not tested any significant models with sss2 and animation (even with just the camera moving) so i dont know how critical it will be. but i do know that in maya you can cache a range of frames into a static sss solution, and my client will be using this feature.. i will not be able to..

if , as you say the sss cache isnt view dependent (seems odd to me this) then i can maybe get away with doing a single cache for a point of view that incorporates the whole model at sufficiently high res (its a city) then fly over it, but since its an interpolated effect, it will be hard to get enough detail all over the model from a single frame calculation, and if i do a fresh cache for each frame (or dont use caching) then i have a good chance of getting shimmering.

Yeah I get what all the various modes are and what I found in my simple dumb test is that the cache worked through the object totally fine. Admittedly my test was quite simple but it help up fine. What type of lighting will there be in the scene?

Maybe a thing to do might be develop a very small app to allow the merging of multiple saved illumination files, similar to the irmap viewer, so you can at least pre render some of the views you'll see? It might be a bit more of a pain in the ass than having it as base functionality but then might be a quicker thing for Vlado to write than a larger vray module upgrade?

[super gnu]

well fingers crossed before i have to start this job (im neck deep in another job at the moment) vlado can update the max build.. i get the impression its an oversight that its not included.

[vlado]

It was more like a one-time specific request for Maya and I never saw a reason to include it in Max until someone asked.

Best regards,
Vlado