whats with the holdup?

[F J]

hey,

 

i need to get me some grass so i started experimenting with VRayFur..

all went fine, the Light Cache started to take longer as i bumped up the fur density.. eventhought this image took 1h45m to calculate the LC, i accepted it cuz at least it got finished..

 

now on this next shot all i did was move the camera to the other side of the house to get another feel of the fur density..

just about everything in LC is set to default, subdivs=500..

i feel like i've set Snail Cache for Secondary Bounces *LOL*

its just stuck there for 2hrs now.. my CPU efficiency seems stuck between 25-30%..

any thoughts?

 

TIA

[Brute Guy]

Hi TIA,

 

Was doing some grass this afternoon, had a few similar excapades, I bring in my grass plane from rhino, mesh it fairly densly, then give the grass a distribution of 3.0 per area, my LC settings are about 1000, but I found that by turning down my Iradiance map to 'low' seemed to speed things up a bit. I'm not sure about the camera movement though? Seems bizzare

 

marc

[F J]

Hi TIA,

 

Was doing some grass this afternoon, had a few similar excapades, I bring in my grass plane from rhino, mesh it fairly densly, then give the grass a distribution of 3.0 per area, my LC settings are about 1000, but I found that by turning down my Iradiance map to 'low' seemed to speed things up a bit. I'm not sure about the camera movement though? Seems bizzare

 

marc

 

hi,

 

my name isnt TIA (that means Thanks In Advance)

 

i dont see how changing Irradiance settings could have an effect over the LC calculation, specially cuz LC gets calculated first..

 

i do know though that Irradiance takes advantage of LC, using information calc'ed in the LC stage to speed up Irradiance calc.. but not the other way around..

 

i ran another test:

reduced thickness by around 60%, so i had to increase the distribution per area to compensate, which is now 1.6 n, as u can see, will still need to increase a lil bit more..

on this example LC alone took almost 3hrs (starting off real slow n exponencially increasing speed), still with a major inefficiency of 25% CPU load..

 

im just wondering if there's any sort of settings i can mess around with to speed up the LC calc stage.. if its not a settings issue, i dont see this improving much rendering over a network, since this PC still got plenty of resources available..

[Q-Bix]

Just a thought....

 

Do you have the Fur set to generate GI? maybe look at turning off GI on the grass object and lighting it independently?

 

That should speed things up, im not sure what it will look like though.....

[Brute Guy]

Lol, TIA, sorry Francisco, twas a night of hard rendering before I replied to your thread, wasn't with it! Grass looks good on the picture, I'm affraid I don't know in that case, could you reduce your LC subdivs?

 

Marc

[F J]

Just a thought....

 

Do you have the Fur set to generate GI? maybe look at turning off GI on the grass object and lighting it independently?

 

That should speed things up, im not sure what it will look like though.....

 

i unchecked both generate/receive GI for the Fur, still takes a long time to calc LC..

 

ran another test:

lowered LC subdivs down to 200, as well as LC interp. smpls from 10 to 5..

increased fur distribution per area from 1.6 to 2.0..

LC calc took a lil bit over 4hrs, still at the inefficient CPU load of 25%

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does anyone know if LC is one of the stages that can take advantage of DR ?

 

TIA

Edited August 6, 2008 by F J
dead link

[F J]

VRayFur? DR?

 

anyone at all?

[F J]

hello again,

 

sorry for digging this up, i figured everyone was on vacation so im trying one last time to get some feedback about this VRayFur issue..

[Stephen Thomas]

Light cache is great for getting a lot of light bouncing around in interior scenes, but for exteriors where you have light coming from all angles you may find that you are quicker using a combination of irradiance map and brute force. You should be able to get away with dropping your secondary bounces to 1 or 2.

 

As far as optimising light cache settings go, no DR I'm afraid. It has to be done on one machine, though obviously make sure you have set the number of passes to match the number of processor cores on your system.

[F J]

hey, thx for replying Stef,

but oddly enough the issue still persists

set QMC 4subdivs for 2nd engine, no change in CPU efficiency..

its like all of the sudden VRay ceases to be multi-core capable..

 

[Stephen Thomas]

Can you post a screengrab of your render settings as well as vray fur and material settings? Or if you want to send me a test scene containing an area of the grass I can take a look at it and see if I experience the same problems.

[pg1]

not entirely sure how vray treat vray fur when it comes to memory management and rendering but i would try changing some of the settings in the v-ray systems panel and see what results you get.

Maybe change the memory management from static (if its set to static) to auto and change you dynamic memory limit up to for example 3000 mb if you got a 4 gig machine (this should help if vray treats fur in the same way it does vray proxies)

face coeficient to 1 maybe

not sure if any of this will help but this panel controls how vray allocates memory and cpu usage so something in there should help

[Stephen Thomas]

Hope the email and scenes I sent helped with that Francisco! For the benefit of anyone else following this thread here is the gist of it:

 

"First off the vray fur settings. I never use the per area setting, I'm not even sure what the area refers to, and I think this was giving you too great a density. Instead use the 'per face' option and I think it works better with a small number per face and a highly subdivided plane rather than low subdivs and a high number per face.

 

Next the GI settings. As I said before, DMC for secondary GI should be faster than light cache in the majority of exterior scenes as you just don't need to bounce that much light around.

 

Also a small point relating to the material for the fur itself. You might have noticed that you can't add a UVW map to it, that's because it only has W coordinates i.e. vertical. Best to stick with a single colour or gradient for this, a slight colour gradient might give a nice variation in colour if you vary the length of the fur."

 

Also I should add that I tend to leave my dynamic memory settings on auto. If you are going to choose dynamic, make sure you have allocated enough. An added benefit of using Irradiance map + DMC for GI is that the lighting calcs can take advantage of distributed rendering whereas LC has to be done on 1 machine.

Edited September 30, 2008 by stef.thomas

[F J]

hey Stef,

u tried just hitting the Render button on my scene, right? did u also experience the CPU inefficiency at 25%?

if so, then i guess there's no way around it..

as i've said, i get the same behavior whether i use LC or QMC..

after some tests i came to the conclusion that the 'per area' n 'per face' settings r just different means to the same end, as u can adjust both settings to accomplish the same fur density..

as u noticed, im using the Dynamic memory setting.. there's still a lot of memory to go around, but i tried using the Static anyways, just in case.. plus i know when the value for the Dynamic setting becomes an issue.. CPU efficiency drops from 100% n the memory graphic goes into a constant tiny zigzag..

oh well, screw it:rolleyes:

guess im gonna try out a bunch of proxies of actual geometric grass patches..

thx anyway everyone..

[ronyuni]

first : sorry for my English.:p

 

i have same issue.

 

just before, i success add some vrayfur effect at blacked, and now i wanna have some rugs on the floor.

and hit render, ....and it take long enough till i decide to kill it!.

 

render went well if the rugs are deleted, while my blanked with vrayfur, render perfectly.

 

and i came on conclusion.

the blanked consist of many faces, while the rugs, as per my regular 3dmax thinking, only happened to have 2 face, to make the polygon counter small, to make 3dmax running smooth.

 

when i set my rugs ( make it from 'plane') have many segment, about 5 cmx5cm per segment, it render perfectly and fast too..

so, to make Vrayfur effect, you must apply on object that has many segment/faces.

i don't know how to explain this, may be the guy from Chaos can.:confused:

 

hope it can solve your problem.