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alvin-cgi
05-11-2008, 12:57 PM
Is XSI instance function same as (LW) HD Instance plugin…

I want to do some basic crowd simulation in XSI, but wondering XSI instance(not Behavior) can do similar thing like LW HD instance.

Thanks

mocaw
05-12-2008, 02:31 AM
As far as I know, yes, and then some.

T4D
05-12-2008, 05:37 AM
As far as I know, yes, and then some.
and more on top of that .

XSI can handle Real objects at levels LW would Have to be using HD.. ( NO joke, REALLY !! )
SO XSI using Instancng means you can handle ..well Hell of ALOT !!!


I done a Battle scene in LW in 8-9 times and just doing one now in XSI and well ,.. I LOVE XSI !!:bowdown:

pooby
05-12-2008, 08:47 AM
I'm not sure that it can.

With HD instance you can instance an object with a piece of animation on it, say, a 30 sec loop.
Then have all your instances pick a random frame from that loop to start from. So you could make a very random looking animated crowd of soldiers from one animation. This I think is Hd'instances' biggest selling point.

the concept of which can be seen here http://www.mediafire.com/?x1hp9wtzng0 (http://www.mediafire.com/?x1hp9wtzng0)

I'm very much hoping that you can do that in XSI but I fear maybe not. please someone correct me if I'm wrong.

HD instance also has a great load of placement and distribution options, but XSI trumps that in general by using Hair guides.

However, HD's 'randomisation' system can be used with the animation offsets, to give each soldier a different combination of clothing items, making sure that each animated soldier has a different coat, hat and trousers etc, (meshes, not just colour (which can be randomised too) but no soldier would be wearing 2 coats.
(I know that soldiers would all be wearing the same, but it's mufti day at the army)

T4D
05-12-2008, 12:03 PM
I have not used the new version of HD with 'randomisation' it sounds interesting

so are you saying a jacket would be deformed as per the instance it's attached to ?
NOT how the master item is being deformed ?
how can it do that ?
I can understand offset frame cycles
but to deform a instance differently to the master object ?? I'm alittle confused ?


My point was In XSi you can have many more master objects to instance
different cycles, different jackets etcs, without slowing down the system

to spread them out you just need your guides correct and you do have a very random battle all running at very high useable speeds when fine tuning ,.

you can even paint and even animate ( using weight maps ) what is instanced and where and how many. it's alot of fun and very stable

and with XSI 7 ..well I'm so looking forward to the options that brings, I saw it when it was called moondust ... and ..I'm so looking forward to that ;)

ThE_JacO
05-12-2008, 12:22 PM
HD instance is a glorified loading and replacement system, which means the memory footprint isn't anywhere as advantageous as it would be if it was real instancing, reason why it can do things like randomized look-ups etc.

XSI's instancing is actual instancing, and the benefit of it is the lookup of a large portion of the data that makes a model always from the same chunk. The downside to it is that the only difference between instances of the same object can be its transformation (SRT), but its shader, point-positions etc will stay the same.

You can still work around it by creating a set of sources for instancing with offsets on the animation etc, but it might not be the same thing and it might fall short of what you visually need without some scripting capability.

Pooby's comments are for the most part, if not the entirety, correct.

mocaw
05-12-2008, 05:32 PM
I read the first post too quickly and didn't see the mention of doing it without behavior! Well that makes a huge difference!

Still, you might want to try just cloning or duplicating models and running a script to offset their animation. With some tweaking you might get similar render times, maybe even better depending on the complexity of the scene and your machine(s) resources. That will require some mr knowledge though...which I'm guessing that some of the LW'ers that are posting still haven't dipped more than a toe into. I say this because I've rendered scenes in XSI without using instances, that in all likely hood would have never rendered in LW.

It's a much more complicated way of doing it than HD instance though...but if you really do this thing all the time you might still want to learn some scripting and/or get and adv. license just for things like this- HD instance isn't in anyway a replacement for behavior.

At worst you could render your static instanced models (trees and buildings etc.) in XSI and your HD items in LW and combine them in post.

I did see somewhere however, and can't find it now, a script that would let you use particles and instances with an animation offset. Anyone know what the file name is or have a link to a post?

pooby
05-12-2008, 10:24 PM
HD instance is a glorified loading and replacement system, which means the memory footprint isn't anywhere as advantageous as it would be if it was real instancing, reason why it can do things like randomized look-ups etc.




No, Its true instancing. It uses it's own renderer and plugs into LW's Volumetric system. I made a scene with about 200,000 of those Imps in, and it took about 3 secs a frame to render and very little memory hit.

so are you saying a jacket would be deformed as per the instance it's attached to ?
NOT how the master item is being deformed ?
how can it do that ?
I can understand offset frame cycles
but to deform a instance differently to the master object ?? I'm alittle confused ?


No, I'm saying that the jackets and clothing items would be separate meshes who's animation matches the original objects and because HD instance randomisation works with a seed number, and separate layers put instances where others are not, you can distribute the different jackets so that each soldier wears only one jacket, but they can be randomly picked.. Its hard to explain, but it works.

I'm not Trying to say HD is better overall or anything, but it does have some very cool features that are very easy to set up.

ThE_JacO
05-13-2008, 09:36 AM
No, Its true instancing. It uses it's own renderer and plugs into LW's Volumetric system. I made a scene with about 200,000 of those Imps in, and it took about 3 secs a frame to render and very little memory hit.

Fair enough, then things changed since I last saw it.
What it does is probably figuring out what combinations you are using considering offsets etc and build a table of permutations, then instances the permutations by its shader.

I've written similar things before for xsi, to run large scenes with particles cloud instancing that would look like you could change properties and offset them, but while doing it on a per-project basis isn't too much work, but a framework to make it generic enough and usable by anybody would take a fair bit of time.

alvin-cgi
05-14-2008, 03:42 AM
Thanks guys, I will "try" both and see... :)

Michael32766
05-14-2008, 04:41 AM
At work we are working on a couple of shots of a large army using HD instance 2.0.
So far it's working pretty well. It will do offset animation and scale and color tints of surfaces.
Right now the pipeline is rig the character, Animate, Bake out the motion as an MDD file, Load the base soldier into the final, apply the MDD file and HD instance that soldier.
You can apply constraints like face towards shortest poly edge etc.
The only draw back is when you have to change the base animation of the soldier.
Then you have to go back to the start.

What I'm wondering about is if in XSi you can do random parenting?
Say you have a base soldier and then randomly parent items like Shields, Swords, Flags to them.
Also can you say here is a base flag with Cloth sim on it. Bake out the motion of the flag, reapply it as a deformation to a flag and make that flag a child of a specific instanced soldier? Also don't collide with other instances
mash

grahamf
05-29-2008, 03:38 AM
The only draw back is when you have to change the base animation of the soldier.
Then you have to go back to the start.

Can you elaborate on that one Mike? Can't you just point the MDD displacement to the new MDD file?


- Graham

grahamf
05-29-2008, 06:00 AM
What it does is probably figuring out what combinations you are using considering offsets etc and build a table of permutations, then instances the permutations by its shader.

That's not in fact what HD Instance does. It's not a trick, hack, shortcut or script. It REALLY does what it says it does. Even if you asked it for a billion different permutations, it still works. It does the instancing rendering by itself with its own code, on-the-fly.

Ideally, I would port it to Mental Ray someday.

- Graham

pooby
05-29-2008, 09:08 AM
You should as it really is a brilliant system.

I'd love to see it in XSI. Especially The animation offset part - Actually, all the controlled randomisation and placement too.

Carm3D
05-29-2008, 09:56 AM
Ideally, I would port it to Mental Ray someday.


That would be sweet! Especially if I can get a cross-platform discount. ;)

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