Particle Overlap - Omni Emitter not Random? - Simply Maya User Community

# 1 04-03-2004 , 05:44 AM

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Join Date: Jul 2003

Location: Bay Area, CA

Posts: 14

Particle Overlap - Omni Emitter not Random?

Good evening,

I'm working on my thesis on Generating Starfields in 3D and have run into a bit of a problem.

Following suggestions by Tolerate and Mr. McKinley, I've created a Starfield using particles. Specifically, this is done by placing an Omni emitter at the origin, setting speed to 0, minimum distance to 600, maximum distance to 900, and then letting the emitter fire away until I have the desired density of stars.

From there, I wanted to add some variation to my stars. Not being too confident with per-particle attributes, I figured the easiest way would be to create a couple more emitters with similar settings and have these emitters fire different particles.

My current set up has three Omni emitters all at the origin:
one for bright yellow stars
one for medium bluish stars
and one for dimmer greyish stars.

Ideally, this would randomly fill the sky with random placements of these three types of particles.

The problem is, all three of my Omni emitters appear to be firing at the exact same locations in space! When all three emitters create a particle at the same spot, the large yellow ones are always seen (being the largest) and the blue and dim ones are unable to be seen, always encapsulated/blocked by the yellow ones.

To prove that this is the case, I put the three different particle types in three layers. If you view them independently, you can see that particles from all three emitters are being placed in the same locations.

How can I fix this?

I tried rotating the emitters, but this made no change.

Any ideas?

Also, if MTMcKinley, Tolerate, Oculus, or NitroLiq happen to view this post - I'd love to give you guys credit once my thesis is complete. If you're willing to give me a little personal information and would like the credit you most definitely deserve, send me a message here or an email to bmrodrig@calpoly.edu . Your full name, and then the company and/or college you most strongly affiliate with would be great.

Thanks in advance,

Brian

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# 2 04-03-2004 , 08:35 AM

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Join Date: Sep 2002

Location: London, UK

Posts: 3,198

You could try connecting turbulence fields to your particles... that should mix up your particles user added image

Kari
- My Website
- My IMDB

Do a lot, Fail a lot and Learn a lot!

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# 3 04-03-2004 , 12:32 PM

Moderator
Join Date: Oct 2002

Location: London, UK

Posts: 2,800

try changing the seed, if you change the seed it should generate completely different results (it's basically a number that maya uses to generate the data, if you alter it you will get differernt results but if you change back to it the results should be exactly the same....well in theory)

Alan

Technical Director - Framestore

Currently working on: Your Highness

IMDB

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# 4 01-10-2005 , 06:56 PM

Registered User
Join Date: May 2004

Location: New York City

Posts: 42

Totally stupid question, but the the life of me, I can't find the seed parameter in the emitter attributes or the particle attributes.

I see the "general seed" attribute in the lifespan section of the particle shape attributes, but that doesn't change the randomness of my emitters.

I too have three seperate emitters that are emitting at the exactly same rate, thus overlapping each other.

Can someone help. Like I said, I small brain cannot find the "seed" parameter if it is different than the above.

Thanks.....

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# 5 02-10-2005 , 06:53 AM

Registered User
Join Date: Sep 2002

Location: Minnesota, USA

Posts: 3,709

Like Pure morning said, Seed is what this is for, but a lazy way would be to Set an initial State offset for 2 of the emitters.

This way, you can fire one emitter, and stop it at, say, frame 10, set its' initial state, then do the same for one more at a different frame, then, rewind and play, and all 3 emitters should be shooting particles all starting from different locations, i.e. locations from emitter center.

Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS
izzylong.com

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