The mushroom cloud is pretty mush finished at this
point, but now it's time for the icing on the cake. This is the rings of moisture
in the air being displaced by the explosion's shockwave and the dirt thrown
out at the base of the explosion. These effects are all achieved through more
animated displacement maps. As this part of the tutorial is really just a
mixture of techniques from parts 1 and 2, so I won't be particularly thorough
here as everything is covered in the previous two parts.
Start off by making a three new patch grids. These will
all be exactly the same so you can cut and paste the mesh into a new model,
but make sure you have three separate models as you will need to have separate
displacement maps for each. These grids should be fairly dense, something
close to the resolution of the mushroom cloud surface. Before I go any further
I'll just say that the reason I'm putting animated displacement maps onto
a square grid rather than animating a ring shape is that animating a ring
shape requires scaling, which alters the patch density of the surface relative
to the camera which in turn creates it's own strange displacement artifacts.
Right, on with the show.
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| A patch grid like any other |
Create a new object, in the front view make a 2 point spline,
snap it to the grid and move it off the Y-axis a bit. Goto the properties
and set the pivot back to X-0, lathe it with eight cross sections. Still in
the front view, make another 2 point spline and extrude it out to eight times.
You will need to load up your image editor again and make another one of those
fantastic gradients. This one needs to start off black at the top, then fade
to white in the middle before fading to black again. This is going to be another
transparency map. Back in A:M import this map and apply it as a decal to your
eight-patch strip. You can move the ring out of the way, that's just for modeling
reference. After you've applied the decal you can lock the strip so you don't
accidentally get your points tangles up with the ring's points. Now you need
to move the strip points on top of the ring's points in the top view. You
will probably get a nasty bulge at one end of the strip, just select the two
offending points and hit the 'p' key to peak them. The curvature for these
two points will be wrong now, but you can fix that be adjusting the gamma.
Once the points have been ordered into loverly ring you can delete the original
ring used for modeling reference.
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 |
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| Make a 2 point spline |
Lathe it with 8 cross sections |
Extrude another 2 point
splin 8 times |
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| Yet another gradient transparency
map |
Use the lathed ring as reference |
Correct the gamma on the
first 2 points |
Make a new action for the ring. Go to frame 0, select muscle
mode, then scale the points down so you have a small disk (scale the inner
ring of points more than the outer ring) and make a keyframe for all the points.
Now go to about frame 80 and scale the points back into a ring again and set
another keyframe. The ring should expand rapidly at first and then slow down
in the latter part of the animation, so make another keyframe at about frame
60 then drag it back to about frame 35 in the timeline. It's easier to do
it this way than it is to try and adjust the interpolation for all the points.
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| Scale the ring to a disc
and set a keyframe |
Scale it out to a ring and
set another keyframe |
Once you're satisfied with the look, create another new
choreography. This will be our standard texture making setup: No lights, orthographic
camera looking down with a square resolution/aspect ratio (about 800x800,
aspect 1). Bring in the ring along with its action and position it under the
camera. Scale the ring so that it just fits into frame when fully expanded.
Now you need to create another material, the standard perlin. Set the noise
to 5, top attribute to white with ambience up to 100%, bottom attribute to
mid grey with ambience also up to 100%. Drop this material onto your ring
and then adjust the perlin scale appropriately. Make sure the material uses
'global axis'. In the choreography you need to animate the the ring along
the Y-axis to get the texture to churn.
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| It should look something like this when
rendered |
Render off this animation, import it in and apply it as
a decal to one of your grids, and change the map type to displacement. Add
the image again to the grid and change the type to transparency. Drag the
'base cloud' material onto it and drag the grid into the main mushroom cloud
choreography. Repeat this process for one of the other grids. In the choreography
position one of the grids above the mushroom cloud and one about the middle.
Obviously, scale both the grids to an appropriate size and flip them over
so that their normals are facing towards the ground. Go back to the ring displacement
generator choreography and change the camera background color from black to
mid grey, render it off again and apply this new texture as a displacement
to the third and last grid, you don't need a transparency map for this one.
Create a new material for it, this material is whatever you want your ground
to be. It looks good if you give this material a bit of a glow so it looks
like a bits of dust has been thrown up into the air. Drag this material onto
your last grid and bring the grid into the main mushroom cloud choreography.
Sit it on the ground plane and then all that's left is the timing of all the
rings going off. You will probably also want the rings to fade to transparent,
which can be done by manually fading the last few frames' color to black in
your image editor.
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| Lay out the grids |
Then render it off! |
This animation can still be taken a lot further, one of
the obvious things that could be done is to make animated color maps for the
mushroom cloud the same way that the displacement maps were generated. On
top of that you can add particles and volumetric effects like dust to give
it that extra realism.
Download
the Project file for Part 4
Home
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Copyright © 2001 by Ilya
Anisimoff. All rights reserved.