Imagine PD 3D/Imagine PD 3D.iso/objects/earth/readme1.txt

Text File | 1994-10-19 | 23KB | 558 lines

The Amiga-Video Journal                  June 1991
                            vol 2 issue 3

3D MODELING -"Earth Rise" - An Imagine Project

by R.L. Kellogg, PhD


Creating an animation of the rotating earth as seen from the moon
was inspired by the incredible animation graphics of the PBS
series "The Astronomers".  Since the Amiga can also produce
quality graphics and animation, I decided to create my own space
art.  The approach was conceptually simple:  digitize a map of
the earth and, using a 3D rendering program, wrap the image
around a wireframe sphere. I would do the same thing again,
creating an "atmosphere" of clouds for an extra effect.  A
digital "stage" could be set, hanging the rotating earth in a
background of stars and filling the foreground with an image of
lunar terrain.


Step 1:  Obtaining the Earth Map


All of the maps of the earth in atlases, back issues of the
National Geographic and airline travel magazines had too much
printing and lettering.  Fortunately, I found one map of the
world that was simply an outline of continents.  It was an easy
matter using Digi-View (by NewTek) to digitize the map as a high
resolution (640 x 400) image in "Line" mode, creating a 2-color
map in only black and white.  By adjusting the brightness
control, I found a setting which clearly showed the continents.

With DeluxePaint-III (by Electronic Arts) set to the HiRes 16-
color mode, I loaded the 2-color map into the 16-color palette.
I then adjusted the palette to provide a range of pastel colors
for drawing yellow-tan deserts, brown mountain ranges, flat-green
forests, and deep blue oceans.

To insure that I only drew inside the continental boundries, I
locked the blue ocean color with the "make stencil" command. This
prevented any of my drawing from altering the ocean.  Then for
several hours I drew deserts, mountains, and forests, using
National Geographic and several other atlases as a guide.
Whenever I was able to make a feature that I liked, I used the
brush command to replicate it.  Mountain chains were easy that
way!  Sometimes I rotated and scaled (using the perspective) the
brush to "fit" the geography.  Every 15 minutes or so I would
save my map to disk, in case of catastrophic failure. In an
evening I had my artwork finished.


Step 2: The Cloud Layer


I wanted clouds over my earth to add some realism. In fact, I
wanted the clouds as a separate layer just hovering over the
earth.  This meant that I needed to draw clouds which registered
to the map that I had draw, but could be separated as a different
rendering layer. Deluxe Paint III has a way of dealing with
separate layers: it has a "fix" command to lock the screen image
into an uneditable background.  This command allows any new art
work to be created on a separate foreground image plane while the
background is still visible.  I locked the finished earth map
into the background and used the airbrush tool to spray on some
white pixels to represent clouds. Then, I picked up those pixels
as a series of small brushes and painted the clouds over the map.
The polar regions were done in solid white, while desert areas
were left untouched.  I put clouds along the western edges of
mountain chains and a tropical depression in the Indian Ocean.
Short jerky motions with the mouse seemed to give the best "cloud
effect", and I changed my brush often.  Once finished, the entire
cloud layer was transfered as a large brush to the alternate DP-
III screen.  Then, with the screen format requester, I collapsed
the number of colors from 16 back to 2 and saved the cloud image,
which now consisted of only white clouds and color zero
background.  For proper use in the 3D rendering program, I needed
the colors reversed.  I used the image utility Butcher (by Eagle
Tree) to exchange the pixel order in the color registers and make
the image a "negative" color. The final saved image was therefore
made of black color zero clouds and white background.


Step 3:  Imagine


God may have created the heaven and earth in six days, but to
learn how to create images using Impulse's 3D rendering program
"Imagine" takes considerably longer.  But the effort is worth it,
and after you get to know the program commands, Imagine becomes a
very powerful 3D rendering program.

First, I established a new project on disk df0: called
"EarthAnim", and from the project screen made a new sub-project
to hold the selected image renditions.  The subproject was titled
"EarthRise-Ham", and on initializing Imagine requests rendering
information of rendering method, screen type, and path.

EarthRise-Ham
    Rendering:  Trace
    Picture:    320 x 400        Aspect 12:7
    Image File: ILBM-12 bit      Ham-yes  Hires-no  Lace-yes
    Image Path: df0:Im_Pix/Ham
    Anim  Path: hd0:EarthAnim    ILBM

Trace was chosen to correctly render the earth's semi-transparent
atmosphere.  The picture size and aspect were from Imagine's
preset list for HAM display.  The image file type, ILBM-12, was
chosen to allow other HAM programs such as Digi-Paint (by New
Tek) and the Art Department (by ASDG).   The complete animation
will not fit onto floppy disk, since each HAM image is about 40K
bytes. In the next article, I'll discuss how to compress the
animation in HiRes format to a file of about 900K bytes.


Step 4: Creating the Earth


The basic work of creating the earth and the lunar foreground is
done in Imagine's Detail Editor. In each case an IFF image is
wrapped onto a geometric shape.  For the earth, it is a sphere.
For the moon, it is a vertical plane.

To start the formation of the earth, I chose "Add Sphere" from
the Function Menu.  In the viewing windows (called "quads") a
small, orange circle appears, and in the perspective window a
small wireframe globe appears.  Moving the mouse to either the
front, side, or top viewing quads and clicking on the center of
the orange circle (the axis origin), I change the circle color to
blue.  Only when the object is blue, that is "pick/selected", can
I manipulate, move, or transform it.

Rather than use the interactive transformations, I needed a
precise change in scale for this sphere.  From the Object Menu, I
select "Transformation" and a requestor appears.  Within the
transformation requestor I select size and set each x,y, and z
axis to 100 units, and "Perform" the transformation.  A large
multifaceted sphere now greets me in the quad and perspective
views. In summary, the transformation I performed was:

Earth Sphere Transformation Properties

size    xyz=    100 100 100    position    xyz= 0  0  0


Step 4: Managing the Attributes


This is by far the most challenging step.  Not only must
intrinsic color and texture properties be assigned to the budding
earth sphere, but the extrinsic properties of the earth from the
map image must be managed as well.  With the earth sphere
"pick/selected" (blue mode), I click on "attributes" of the
Object menu.  The following intrinsic properties were assigned:

Earth Sphere Attribute Properties

name:        Earth
color:         255/255/255        dither:        255
reflect:    0/0/0            hardness:      5
filter:        0/0/0
specular:    100/125/175        index refraction: 1.00

The specular color is essentially a blue-white highlight, which
with the low value for hardness, will create a reflection
highlight with a broad diffuse area.  For this kind of an object,
fairly high dithering is required to prevent "zoning" or "steps"
in the color gradients of the final rendering.

Special care must be taken with the earth map to insure that it
wraps correctly around the sphere as a "brush attribute". The
method is slightly different for a "wrap" that for a "flat"
transfer.  For the map, I wanted to wrap it around the sphere's
z-axis. Therefore, clicking on  the Brush-1 "brush attribute"
box, the following extrinsic properties were assigned:

Brush Attribute Properties

brush name:    df0:Im_Images/EarthMap-colormap.pic
brush type:    color
wrap type:    flat x
        wrap z

The most difficult part of assigning the "brush attribute" is
placing the brush axes onto the designated object.  Since this is
to be a "wrap", the z-axis of the brush needs to be near the z-
axis of the object, the y-axis of the brush nearly non-existent,
and the x-axis of the brush must extend slightly beyond the
sphere's actual size. Within the "brush attributes" requestor, I
chose the "transform" axis option to precise set the earth map
axes:

Brush Attribute Axis Transformation Properties

size    xyz= 110  4  300    position    xyz=  0  -2  -150

The x-axis was made slightly larger than the 100-unit earth
sphere.  The y-axis of the brush is nearly non existent. However,
the brush y-axis position at -2 is very important, since the it
needs to be ever so slightly to the left of the object axis.  The
z-axis of the brush is used for scaling the image, and the map is
stretched upward depending upon the size of z.  The position of
the z-axis at -150 (that is, one half of 300) insures image
symmetry with respect to the earth's equator.

After "performing" the axes transformations, I always like to
make a visual check.  Still within the "brush attribute"
requestor, I click on the "edit" option which allows interactive
positioning (move, using the "m" key) or scaling (size, using the
"s" key) or rotating (using the "r" key). A yellow set of axes
appears over the earth sphere, showing the brush axes inside a
rectangle. From the front view, the upper right quadrant of the
axes rectangle should cover the right half of the sphere.  In the
top view, the axes rectangle should look like a long, thin box
going horizontally through the middle of the sphere. Everything
correct, I tap the "spacebar" and exit the "brush transformation"
requestor and "brush attribute" requestors.  The earth sphere is
saved as df0:Objects/earth.obj.  I use a convention of naming
objects ".wire" if it is just a wireframe object or ".obj" if
I've attached attributes.


Step 5: An Onion Skin Atmosphere


Clearing the Detail Editor, I created another wireframe sphere to
hold the cloud image in a manner similar to the earth.  However,
the wireframe sphere will be slightly larger than the earth, for
in the next step will slip over the earth just like a layer of
onion skin. Therefore the size of the "Add Sphere" was 105 units
in x,y, and z.

Clouds Sphere Transformation Properties

size    xyz=    105 105 105    position    xyz=    0 0 0

The following intrinsic properties were assigned in the
"attribute" requestor:

Clouds Sphere Attribute Properties

name:        Earth-Clouds
color:         255/255/255        dither:            255
reflect:    0/0/0            hardness:     10
filter:        0/0/0
specular:    110/110/110        index refraction 1.4

The atmosphere is made slightly harder that the earth beneath,
and the index of refraction is set to 1.4. The index of
refraction gives an exaggerated sense of depth between the earth
and the clouds. Experimenting with the index of refraction can
have some very exciting effects, especially if the earth and
clouds are viewed from the night side. A glittering halo effect
can be produced.

The extrinsic properties of the clouds again come from a "brush"
picture, but this time I use a "filter" brush rather than a
"color" brush, to create a transparent atmosphere.  Transparent,
that is, except were color zero exists, which will reflect light
just as real clouds.

Brush Attribute Properties

brush name:    df0:Im_Images/EarthMap-clouds.pic
brush type:    filter
wrap type:    flat x
        wrap z

The same kind of wrapping technique is used, but the brush axes
are slightly larger to cover the larger wireframe sphere:

Brush Attribute Axis Transformation Properties

size    xyz=    110  4  300    position    xyz=     0  -2  -150


Step 6: The Earth-Clouds Group


The earth and atmosphere spheres with their attributes were saved
separately as earth.obj and clouds.obj.  Then, still in Imagine's
Detail Editor, I load both objects at once and use the "Pick All"
command from the Pick/Select Menu.  With them both "picked",I
grouped together using the "Group" command from the Object Menu.
Both objects are now bright blue. This combine group of two
spheres is saved as df0:Im_Objects/earth.grp.  Now  I can treat
"earth.grp" as a single entity and think of it simply as the
object "earth-clouds".


Step 7: The Moon Picture


Although Imagine offers 3D rendering of terrain (or importing
terrain from programs such as Vista by Virtual Reality), I had a
terrific 2D HiRes image of the lunar horizon from Apollo 15
(which conincidentally is available from Virtual Reality).  I
wanted to use this image as a foreground "prop" on my 3D
rendering stage.  Therefore, in the Detail Editor I created a
rectangular plane and pasted the picture of the moon onto it. To
do this, I clicked on "Add Primitive" from the Function Menu and
selected "Plane" within the Primitive Types Requestor. I created
a plane with the following parameters:


Plane Parameters:        200    width
                50    height
                5    horizontal sections
                5    vertical sections

After "pick/selecting" the plane, I attached the image of the
moon horizon as a brush attribute:

Plane Attribute Properties

name:        Moon
color:         255/255/255        dither:        230
reflect:    0/0/0            hardness:      0
filter:        0/0/0
specular:    0/0/0            index refraction 1.0

Brush Attribute Properties

brush name:    df0:Im_Images/MoonHorizon.pic
brush type:    color
wrap type:    flat x
        flat z

Since I just want to "paste" my moon picture onto this
rectangular plane, the "wrap type" for both x and z was chosen as
"flat-wrap".  This means that the moon brush axes must have an
origin just to outside the lower left-hand corner of the
wireframe plane. The result was:

Brush Attribute Axis

size    xyz=    404  4  250       position    xyz=  -202  -2  -52

The x-axis was scaled to be just as long (wide) as the rectangle,
and the z-axis about five times higher.  The z-axis scale was
done by trial and error to fit the moon horizon image into
pleasant proportions onto the rectangular frame. The finished
object with attributes was saved as df0:Im_Objects/moon.obj.


Step 8: Actors Upon a Stage


The metaphor of a "stage" in 3D rendering is very appropriate:
the camera, objects, lightsources, etc. become actors which are
positioned, moved or changed according to a director's script.
Within Imagine's Stage Editor, the interactive stage is
represented by the quad viewing windows and the director's script
is represented by a frame to frame sequencer accessible from the
"Action" command of the Object Menu.

The following sequence prepared my stage for 64 frames of the
rotating earth.  I worked between the "Action" director and the
interactive Stage Editor to position and align my objects.
However, for this tutorial, all of the setup work can be done
directly within the "Action" director.


Step 9: Action, Action


Clicking on "Action" in the Stage Editor's Object Menu, I enter
the "Action" director screen.  "Action" commands are selected at
the top of the screen in command boxes.  Going left to right
across the screen are the frame numbers (with initially only one
frame), and scrolling down the screen are the actors.  Initially
there are only two actors, "camera" and "global" (really a "stage
hand" who represents global stage settings).  Additional actors
are inserted at the line called "new".  Each actor has settings
of "actor" name, "position", and "alignment".  I'll ignore
"hinge" and "F/X" (special effects) until another tutorial.

a) I first click on the Highest Frame Number and change it from 1
to 64. Across the "Action" field, the frame numbers 1 to 64
appear.

b) I add my cast of characters one at a time using the "Add"
command.  The first object I add is the earth.  At the line of
"new" object, at the intersection of "frame 1" and "actor" I
click the mouse.  Imagine expects two mouse clicks in the add
mode: one for the starting frame and one for the ending frame.
With my first click at frame 1 the "add" command becomes hatched.
Then, using the scrolling bar, I find the intersection of "frame
64" and "actor". I click again.  A red bar appears and fills the
actor line from frames 1-64. Then a requestor asks for the kind
of object I'm adding. The earth is a "normal object", which on
the next requestor I identify by filename as
df0:Im_Objects/earth.grp.  No cycling or transitioning effects
are required.  Within the "Action" screen, the "new" actor is now
automatically chrisened "Earth-Clouds", derived from earth.grp's
attributes.

c) I repeat this procedure, adding into frames 1-64 the new actor
object df0:Im_Objects/moon.obj.  It appears within the "Action"
screen as actor "Moon".

d) I add another new actor into frames 1-64, but the type object
is "Light Source".  At the requestor, I define it as a spherical
light with full intensity of 255/255/255. Its stage name
automatically becomes "Lightsource".

e) I add a second spherical lightsource into frames 1-64, but
click the requestor boxes for "Cast Shadows" and "Diminish
Intensity".  Full intensity is set at RGB of 200/200/200.  Its
stage name becomes "Lightsource.1"

f) I add a final object into frames 1-64, but its type is simply
"Axis".  Its stage name automatically becomes "Track".


Step 10: More Action


Now, I switch back in the "Info" mode of the "Action" director.
If I stopped here and went back to the Stage Editor, I'd find all
my objects piled up on top of each other at the stage position
xyz= 0,0,0.  Therefore, I must move the actors to their proper
positions.

The earth will be "upstage" and slightly to the left.  The camera
will be a considerable distance "downstage".  In the camera's
foreground will be the rectangle holding the moon's horizon.
Illumination for the earth will come from LightSource off to the
right, giving the illusion of a gibbous earth. My other light,
Lightsource.1 will closely illuminate the picture of the moon.
Not wanting two "suns" to illuminate the earth, this light must
be placed such that the moon picture blocks any of its light and
only casts a shadow onto the earth. (That's the reason for it's
"cast shadow" mode).  Lastly, the Track axis will left at xyz=
0,0,0 as an object for the camera to point at.

Remaining within the "Action" direction, and using the "Info"
mode, I click on each of the actor's green "position" bar at
frame 1 and change positions:

a) Camera:        xyz =    0 -1000    0
b) Earth-Clouds        xyz =  -50   400  100
c) Moon            xyz =    0  -320  -80
d) LightSource        xyz = 1000  -250  100
e) LightSource.1    xyz =    0  -600 -150
f) Track        xyz =    0     0    0


Step 11: Point and Twist


I'm almost done setting the stage. However, three of the actors
need special attention while in the "Action" director:

a) Camera:  I delete the blue "align" bar at frame 1, switch to
the "add" command and double click on the camera's frame 1 align.
A requestor appears asking whether to Tween, Align or Track.  I
select "Track" and at the next requestor, inform Imagine that the
camera should follow the Object Name "Track".  No camera rotation
is required.

b) Earth-Clouds: I delete the blue "align" bar at frame 1, switch
to the "add" command and click once on Earth-Clouds frame 1 align
and then once on frame 32.  To make the earth appear in different
perspective rotations, I select "Tween" and at the next requestor
inform Imagine that it must change the alignment in between
frames 1-32 by z = 180 (degrees). This will sequentially rotate
the earth over 32 frames from its inital alignment to half way
around. I repeat this procedure, clicking once on frame 33's
align and then once on frame 64.  I select "Tween" again, but set
the z axis of rotation to 360.  This finishes the task of
rotating the earth.  Imagine's logic compensates for looping, so
although frame 64 ends up exactly at 360 (zero) degrees rotation,
frame 1 actually is adjusted to start at 5.625 (360/64) degrees.

c) Global: Using the "Info" command, I click on the red "actor"
bar at frame 1.  The only global property I need to change is
"Star Density" for the number of background stars which Imagine
will automatically generate. A star density of .01 looks nice.

I exit the "Action" director by clicking "Done"


Step 12: What Does The Stage Look Like


Within the interactive Stage Editor, I select from the Display
Menu "Camera View".  If I've done everything correctly in the
"Action" director, the perspective view should show a wireframe
earth slightly above and to the left of center. The bottom half
of the view should be covered by the moon-plane's rectangular
mesh.  If everything appears to be in its proper position, I
select "Last Frame" from the Frame Menu" and check again.  In
creating animations sometimes I managed to lose my actors.  If an
actor is missing, I return to the "Action" director and check
that the actor's line goes completely between frame 1 and 64
(camera and global are the exception).

Before leaving the Stage Editor, I "Save Changes" from the
Project Menu.  I've forgotten to do this more than once, and it
is very disheartening to lose the results of all this stage
planning.


Step 13: Rendering.


In the Project Editor, I alway render one test frame before
rendering the entire set of images.  At 10 minutes per image (on
a 28 MHz machine), that's a little over 10 hours for a 64 frame
animation. Therefore, caution is warranted.  I select frame 14
and click on "Generate".  When complete, an asterick (*) appears
below frame 1.  Now comes the moment of truth. With frame 14
still selected, I click on "Show".  Moments later I'm seeing a
HAM image of the earth rising above the moon's horizon.

By my subproject specification, this picture was automatically
stored as df0:Im_Pix/Ham/pic.0014. The directory path to a floppy
disk is inadequate for holding the complete animation.  I can
check my animation directory path for this subproject  clicking
on the "Modify" box of the Project Editor.  Large frame
renderings can be only done on a path to hard disk. My selected
directory path is hd0:EarthAnim. Confident of my results, I
select the range of frames 1-64 and click "Generate".  See you in
the morning!

If you would like a disc containing a copy of the earth map,
cloud layer and moon horizon images; the earth, clouds, and moon
objects and the completed "Imagine" 3D rendering stage; and the
completed rendering of frame #14 as Ham, HamE, HiRes, and ILBM-24
of this animation, send $5.00 to cover postage and handling to:

            First Principles
            Dr. Robert L. Kellogg
            7509 Dew Wood Drive
            Rockville, MD 20855