create a meteor using the particle system in softimage xsi
TRANSCRIPT
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Tutorial • A Meteor
A Meteor
This tutorial was written by Sim Yee-Kian of the Avid Singapore office.
Create a Meteor using the Particle System in SOFTIMAGE|XSI.
Summary
In this tutorial, you will:
• Use a sphere as the emitter for a particle system.• Make the particle stream behave like the meteor’s tail.• Give the particle stream a fiery red-orange color.• Deform and texture the sphere to make it look like a meteor.• View the result in the render region.
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Tutorial • A Meteor
Creating the Meteor
1. From the Simulate toolbar, select Get > Primitive > Surface > Sphere.
2. Reduce the sphere’s Radius to 2.
3. Rotate the sphere about the Z axis to –65.
Rotating the sphere puts it on an angle, as if it were falling from the sky. Later on, the sphere’s angle will affect the direction of the particle stream.
4. With the sphere still selected, choose Create > Particles > From Selection from the Simulate toolbar.
This turns the sphere into an emitter for a particle system. If you’d like to see the particles being emitted, click the Play icon to play back the default 100 frames.
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Tutorial • A Meteor
Making the Meteor’s Tail
5. In the ParticlesOp property set, change the following parameters:
- Set the Execution State to Interactive.
Now the particle stream animation is updated from the start frame, whenever you change a particle parameter.
Note: On slower computers, it might be better to leave the Execution State set to Not interactive, and refresh the animation at playback time.
- Set the Start Frame to -100.
Setting a negative start frame creates a pre-roll for the particle system. When the animation is played from frame 1, the particle system has already been calculated for 100 frames prior to frame 1. That way, the particle stream (meteor tail) already exists at frame 1.
6. In the Emission property set, change the following parameters:
- Set the Emission Direction to Local.
This makes the particles travel in a straight line instead of flying off in all directions.
- Set the Rate to 1000 and the Variance of 50.
These parameters determine the number of particles emitted by the system. A variance of 50 will generate a semi-randomness in the emission, making the rate range between 950 and 1050 particles.
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Tutorial • A Meteor
Note: On slower computers, reducing the ParticlePercentage value, in the ParticlesOp property set, to 20-50% will speed up previewing. Just remember to set it back to 100% for final rendering.
- Set the Spread to 8 and the Variance to 5.
The spread specifies how the particles spread away from the center of the stream as they fly outwards from the emitter. Variance randomizes the spread.
- Set the Speed to 5 and the Variance to 3.
7. In the Particle_Type property set, click the General tab and change the following parameters:
- Set the Maximum Life to 3.
Increasing the life span of the particles creates a longer particle trail, or in this case, a longer tail for the meteor.
- Set the Birth Size to 0.15.
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Tutorial • A Meteor
Setting the Tail’s Rendering Properties
8. In the Particle_Type property set, click the Rendering Properties tab and change the following parameters:
- Set the following RGBA values in the Color section:
R:0.948G:0.352B:0.069A: 0.648
This will give the tail an orangey-red look like a burning meteor. If you’d like, you can change the RGB values to R: 0.077, G: 0.579, B: 0.983, A:0.648 to create the icy blue color characteristic of an ice comet.
- Go to frame 1 of the scene, and click the animation icon next to the Display Color option to set a keyframe. Then go to frame 50, reduce the A value to 0.448, and set another keyframe.
Animating the A value changes the particles’ alpha value over time. In this case each particle will become more transparent near the end of its life span.
- In the Animation Reference section, set the Alpha value to Age%.
This ensures that the animation that you put on the particles’ alpha value will continue to affect the particle as it ages.
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Tutorial • A Meteor
- Set the following HLS and Alpha values in the Jitter section:
H: 0.05L: 0.069S: 0.05Alpha: 0.036
Jitter values add color gradation between the particles. The different shades of orange (or blue) give a more realistic look to the particles.
9. In the Particle_Type property set, click the Shader General tab and change the following parameters:
- Set the Additivity to 1.
Additivity gives the particles their bright glow. When particles overlap, the luminance values are added together which creates a higher intensity of color.
- Set the Motion Blur values to:
Forward: 0.7Backward: 0.7
Feel free to play around with the motion blur values to get the look you want.
Leave the default values for all other parameters.
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Tutorial • A Meteor
Making the Meteor Look Like Rock
Note: Since the particle system is regenerated each time you change the meteor, you may want to return to the ParticlesOp property and set the Execution State to Not Interactive before you begin.
10.From the Render toolbar, choose Get > Material > Lambert. Leave the default values.
11.With the sphere still selected, choose Get > Texture > Rock.
- From the Texture Support tab click the New button to create a new texture space. Select UV from the menu.
- From the Rock tab set the following values:
Grain Size: 0.092Diffusion: 0.245Mix Ratio: 0.5
12.Select points on the Sphere and translate them around to deform the sphere and give it a more rock-like shape.
13.Now, making sure that the sphere is still selected, choose Get > Property > Glow from the Render toolbar.
This gives the meteor the kind of glow that it might have as it enters the atmosphere.
14.Move the play cursor to a frame somewhere in the middle of the animation.
15.Now press Q to activate the render region tool, and draw a render region in your Camera viewport to see how your meteor will look rendered.
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Tutorial • A Meteor
16. If you are satisfied with the way it looks, go ahead and render the scene.
You can play around with some of the particle system’s other parameters to further change the look of your meteor.
Enjoy!
Questions & comments: [email protected]
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