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VOLUME USER SURVEY: Usage side: Workflow/Drawbacks

 
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schoenberger
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Joined: 02 Mar 2005
Posts: 3785

PostPosted: Wed Oct 17, 2007 12:37 pm    Post subject: VOLUME USER SURVEY: Usage side: Workflow/Drawbacks Reply with quote

This is a small user survey about the Binary Alchemy volume shaders.
In case you are not a direct user, please forward this email to your shader artists.
If we get enought replies for the the survey and it was effective,
then it will lead into a FREE UPDATE from v3.0 to v3.x.



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2. Usage side: Workflow, Current Drawbacks,
most time consuming parts
---------------------------------------------------------------------


a) STARTUP, GET A FIRST RENDER LAYOUT
You get a new task which will perhaps be solved with the volume shader.
So you have to deliver something to your supervisor to show it can be done.
- what are your main steps/workflow steps?
- what takes you the most time to get a first result?
- Any steps you are not understanding?
(You are tweaking some parameters but you don't know if it helps to increase or lower the parameter value.
You are just playing with the parameters and checking the rendering)
- Have you reached a limit?


b) GET THE VOLUME TO SOMETHING SUITABLE FOR THE PRODUCTION
Ok, first result looks promising, you are resposible to create the volume rendering for the production.
You have to get it to the final look. Right shape, right textures, right light/shadows...
- what are your main steps/workflow steps?
- what takes you the most time to get?
- Any steps you are not understanding?
(You are tweaking some parameters but you don't know if it helps to increase or lower the parameter value.
You are just playing with the parameters and checking the rendering)
- Have you reached a limit?


c) FINAL TUNING
You got it to something which was approved by supervisor and customer.
Now you have to fiddle with the last steps.
Perhaps some small flicker, light is not completely right, it just misses some final touches.
- what are your main steps/workflow steps?
- what takes you the most time to get?
- Any steps you are not understanding?
(You are tweaking some parameters but you don't know if it helps to increase or lower the parameter value.
You are just playing with the parameters and checking the rendering)
- Have you reached a limit?
_________________
Holger Schönberger
Binary Alchemy - digital materialization


Last edited by schoenberger on Wed Oct 17, 2007 3:57 pm; edited 1 time in total
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lyn



Joined: 06 Apr 2005
Posts: 17

PostPosted: Wed Oct 17, 2007 3:01 pm    Post subject: Reply with quote

2. a) I start with a rough scene and layout the effect.
Rough in any animation thats needed. Setup some lights,
then start on the shader.
More often than not this involves checking one of the
example scenes to see what was done there
and then modify from there. This doesn't take much time but it is an added step.
I don't work with shaders as often as needed to keep the skills up, so
I end up having to " relearn " things because it has been a while sense I was last in shader land and this is something that slows me down. Presets are good!

b) This is where most of the time is spent, getting the look vs. speed vs. quality. At this point its time to finalize animation (if any) and finalize lights, and check scale because thats a huge problem if its not set correctly.
Then we start messing with the shader to finalize the look and get it to render in a reasonable amount of time, which in commercial production is something of an oxymoron, it's never fast enough.

c) Flicker seems to be the big one as far as troubleshooting, the rest of this stage is render time and quality. This is where we try to optimize things and look at all the sampling parameters to try get rid of any flickering, and also try and get that elusive quality vs. speed balance.

Render time is always the limit. I think you have provided a great set of tools in this shader collection. I have never worked with it a said you know I wish it had "x" node.
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goshone



Joined: 11 Oct 2006
Posts: 68
Location/Company/Country: hydraulx, Santa Monica

PostPosted: Wed Oct 17, 2007 7:51 pm    Post subject: Reply with quote

a) STARTUP, GET A FIRST RENDER LAYOUT
You get a new task which will perhaps be solved with the volume shader.
So you have to deliver something to your supervisor to show it can be done.
- what are your main steps/workflow steps?

I usually work out the initial look and motion using Maya particle clouds. If I can get by with using this, I will usually go with that (soft dust, simple steam, etc.). Most likely, this will not cut it however, but I can use the setup to pipe attrs directly into BA_volume shaders.

Very important: particles cannot be set to clouds when using BA_volume - it just doesn't work.

I go thru the steps of adding the shaders to the network. We are working on some scripts to automate this, possibly with presets, so an artist can make the shader with a single click. This is the one of the more compliated steps, or at least the step where most of the errors occur.


- what takes you the most time to get a first result?

Initial shader setup and verifying cache attribute reads. The PT_loader could be improved for faster setup. Possibly automatically finding the particle cache from the actual scene solver.


- Any steps you are not understanding?
(You are tweaking some parameters but you don't know if it helps to increase or lower the parameter value. You are just playing with the parameters and checking the rendering)

Preliminary setup is fairly straightforward, once you understand the shader connections/setup. I guess one thing would be the radius of the particles seems to be twice as big as the resulting volume, but this may just be a characteristic of volume rendering in general.


- Have you reached a limit?

Not this early in the process. Possibly the PT_loader cache read is often troublesome (loading wrong cache file, frame values are incorrect, etc.)



b) GET THE VOLUME TO SOMETHING SUITABLE FOR THE PRODUCTION
Ok, first result looks promising, you are resposible to create the volume rendering for the production.
You have to get it to the final look. Right shape, right textures, right light/shadows...
- what are your main steps/workflow steps?

Once a basic look is reached, it is really a matter of balancing look vs. render time. Focusing on the marching/lookup sections, we are able to dial in memory usage and rendering speed.


- what takes you the most time to get?

A lot of time is spent on the texture (size, frequency, octaves, distort) to get the desired look. Adjusting the lighting and shadows are time consuming, as well.



- Any steps you are not understanding?
(You are tweaking some parameters but you don't know if it helps to increase or lower the parameter value. You are just playing with the parameters and checking the rendering)

1. The marching section is still a bit mysterious. I use simple mode for the most part, but still find it difficult to get optimal ray marching settings.
2. The general section of the BA_particle_density node has roll and screw parameters which are unclear. I haven't explored them fully, but the docs are very brief about these. Are these just simple random values per particle, or is an accumulating value over the particle lifespan?
3. The flow texture section. This sounds like a very nice feature, can we expand on this?
4. Under misc, there are controls to manupulate the shape of particles based on size and neighbor distance. The latter seems to behave opposite of what I would expect, and I was baffled by the "hint" to use them together - what effect does that produce?


- Have you reached a limit?

Often, we are asked to get a specific look (more wispy smoke is a big request), and find it hard to determine which slider to move. For "more detail", do we increase noise octaves, or gradient bias, or contrast?
Actually, one difficulty is getting volumes that gradually go from very opaque to nearly transparent. What we usually end up with is a very fast dropoff, and can't get a soft fade. Imagine a blast of baby powder, that starts out with opaque points, then diffuses out to almost a uniform volume. Very difficult effect in general, but hard to get with a single particle system using BA_volume.


c) FINAL TUNING
You got it to something which was approved by supervisor and customer.
Now you have to fiddle with the last steps.
Perhaps some small flicker, light is not completely right, it just misses some final touches.
- what are your main steps/workflow steps?

Continue to adjust the lookup section, balancing memory limits with cell size. Possibly adding more lights, or ambient occlusion.


- what takes you the most time to get?

Sometimes preview renders take a long time. Don't get me wrong, this is one FAST volume shader, but if you change one wrong parameter, it can slow to a crawl.


- Any steps you are not understanding?
(You are tweaking some parameters but you don't know if it helps to increase or lower the parameter value.
You are just playing with the parameters and checking the rendering)

see above


- Have you reached a limit?

I have had issues with rendering holdout objects, which are critical to getting convincing volumetric effects. Sometimes, simply changing the matte opacity to "black hole" doesn't work, while it works in almost every other situation. We have had to make custom shaders to overcome this. Memory limits are also on the list here.
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rconover



Joined: 20 Apr 2005
Posts: 26
Location/Company/Country: Montreal

PostPosted: Mon Feb 11, 2008 10:30 pm    Post subject: Reply with quote

For me I'd say two things would really help me.
1) Presets on complex but typical presets/trees.
Every time I come back to BA I aften start on something I tweaked from before-which in turn may be based on one of the example scenes.
The more different types of presets there are the better.

2) Getting that last 10% of photo-real always takes 90% of the shot's production time. Your heart is in the right place with the preview mode.
But sometimes we don't want the see the over-all combined effect-ie this is what the render region/IPR is for. We want the context as it relates to a
paramter/node. XSI's shaderball system seems to be the means to an end here-but not every node is supported in a useful manor. For example BA_particle_density3 doesn't seem to have a good representation in the shaderball. But BA_fractal4D_scl is better.
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