Asteroids in Imagine 3D

OVERVIEW:

This tutorial will demonstrate how to make a model of an asteroid with a minimum of time and effort.   The method makes use of “blob” objects in Imagine for Windows 3D modeling and ray-tracing software.  To get more information on modeling with blobs check out Bill Boyce’s Blob Tutorial.


STEP ONE:

Create a sphere.  To do this, select the menu item Object|New|Sphere as shown below.

Object menu - New Sphere


STEP TWO:

Now redefine the sphere as a blob.  To do this, first click on the sphere you created to make sure it is selected.   Then use the Functions|Blob Attributes menu item as shown below.  Set the mesh density to 3 and the strength to 1.
(Note: There is a good diagram of the effects of the blob strength setting in Bill Boyce’s Blob Tutorial)
Use a low mesh density to keep the polygon count of the finished object as low as possible.   This will help keep rendering times reasonable.   Later, you can add textures to hide the fact that the polygon density is low.

Functions menu - Blob Attributes

 

STEP THREE:

Using the Object|Copy command, make two copies of the blob and set them side by side.   This gives us the basic body of the asteroid.

Blob copy

 

STEP FOUR:

Make several more copies of the blob and place them randomly around the main body of the asteroid.   Vary the size and strength settings of the blobs.  To make craters or dents in the asteroid, set the strength of a blob to -10 and place it near the other blobs.   This will cause that blob to take a bite out of the blobs it comes in contact with.
You may be wondering by now why the perspective preview of the object doesn’t look right.   This is because the blobs must be grouped   together before the blobs can react to each other.   To do this, select all the blobs and click on the group button.
(Suggestion: Click on the center blob first, then use the Pick|All menu item to select the rest of the blobs.  This will make everything group to the center of the asteroid)

Group blobs

Now move, scale, and adjust the strength of individual blobs to change the shape of the asteroid.   Play around with the blobs and use the perspective preview until you get a shape you like.
Before we continue, do a quick render to check your object.

Asteroid quick render

STEP FIVE:

When you are happy with the shape of your asteroid, use the Object|Mesh Blobs command.   This will delete the blobs and leave a single object skin in it’s place.   The command also has left behind the axes of the blobs, so we are going to clean those up.   First, Ungroup  ungroup the asteroid.  Click on the center axis that everything used to be grouped to.   Then use the Pick|Reverse Pick command.  This will select all the axes except for the center one.   Press the delete key to delete the selected axes.

STEP SIX:

Now add some color and textures.  Pick a grayish-brown color similar to NASA images of asteroids.   Then add Ingvar Lybing’s Fractal Bump Texture.

Texture attributes

That’s all there is to it.  Do some renderings to see what it looks like. You can adjust the texture and color, add specular highlights, add more textures.   I would recommend playing with Alan Bucior’s textures.  Some good ones to try for this object are ABDented, and ABColorHeight.   Here are some sample renderings with different texture settings.

Asteroid rendering with fractal bump textureRendering with Fractal Bump texture, as explained in the tutorial.  The default settings for the texture were used.

 

Asteroid rendering with fractal bump texture, ABDented texture, and specularityRendering with specularity, Fractal Bump, and ABDented textures. The basic color was darkened. The darker color combined with specularity give the asteroid a glossy obsidian look.

 

Asteroid rendering with fractal bump, ABColorHeight, ABDented, ColorNoise texturesRendering with ABColorHeight added, and ColorNoise texture. The ABColorHeight texture is adding a reddish color to the bottom of craters. The ColorNoise texture is using three similar shades.

Download this asteroid model.