If you're new to viewing 3D art, you may find that images over 15 - 18
columns are too wide. This is because your eye muscles will need time to
strengthen and your brain will need time to learn to relax the eyes to
very wide angles before you can unfocus by a large amount. Persevere, it's
worth it and some people reckon it improves their eyesight!
__________________________________________________________________________
4. Changing depth
When the brain calculates how far away an object is, it measures the
angle between the two eyeballs. The closer the eyes are to being parallel,
the further away the object. As we have seen, getting the brain to overlap
two separate images gives the impression of there being one image at a
different depth. Therefore it follows that if we adjust the gap between
the repeated images, we can alter the depth at which the object appears.
If we take two objects again, but this time draw them with different
spacings -
. .
/|\ /|\
/ |:\ / |:\
/ |:/ / |:/
/___|/ /___|/
. .
/|\ /|\
/ |:\ / |:\
/ |:/ / |:/
/___|/ /___|/
. .
/|\ /|\
/ |:\ / |:\
/ |:/ / |:/
/___|/ /___|/
Start at the top two and get the single 3D image. Now if you look down
you should see that the next pyramid is closer to you. The bottom pyramid
is closer still.
To make the pictures symmetrical, I've decreased the spacing by two
characters each time. Changing the spacing by a single column gives you
more control over the depth of the image.
The general rule for viewers who relax their eyes (wide-eye) is that
bringing images closer together makes them appear nearer to the viewer,
spacing them out makes them appear deeper into the picture. Cross-eyed
viewers will see the effect in reverse.
We'll take the pyramids again, but this time copied across the screen
with a single space between each layer -
. . . . .
/|\ /|\ /|\ /|\ /|\
/ |'\ / |'\ / |'\ / |'\ / |'\
/ |'/ / |'/ / |'/ / |'/ / |'/
/___|/ /___|/ /___|/ /___|/ /___|/
. . . . .
/|\ /|\ /|\ /|\ /|\
/ |'\ / |'\ / |'\ / |'\ / |'\
/ |'/ / |'/ / |'/ / |'/ / |'/
/___|/ /___|/ /___|/ /___|/ /___|/
. . . . .
/|\ /|\ /|\ /|\ /|\
/ |'\ / |'\ / |'\ / |'\ / |'\
/ |'/ / |'/ / |'/ / |'/ / |'/
/___|/ /___|/ /___|/ /___|/ /___|/
The change in depth between each layer is smoother, but equally is less
pronounced.
I aligned the middle columns for symmetry, there's no actual need to do
this, sometimes it looks better if the images don't line up. In the above
example, the pyramids don't get out of step by more than a couple of
squares, but as we will see in the next section, it can become a problem
ensuring that different layers don't drift too far horizontally from each
other.
When it comes to deciding depths, it's worth remembering that most
viewers will expect the images at the bottom of the screen to appear
closer than those at the top.
__________________________________________________________________________
5. Multiple layers
Changing the gaps between columns produces different layers, but the
previous example is a bit cold and disjointed - the individual images are
flat and they don't interact with each other. A much better 3D effect is
gained when layers of objects at different depths are laid on top of each
other, or when one of the images contains more than one layer.
When discussing layers, I often use the term one layer deeper or one
layer nearer. If I say I've pushed a set of images one layer deeper into
the screen, it means I've added one extra column of spaces in between the
images. Bringing images one layer out of the screen involves removing a
column of spaces between the images. If the layer is continuous, then I've
either reduced it or widened it by one column.
Let's look at a simple example of the images containing multiple layers
first. Two squares (in case you weren't sure!) -
____________ ____________
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
|____________| |____________|
Completely flat and uninteresting, so lets add another square in the
middle -
____________ ____________
| ________ | | ________ |
| | | | | | | |
| | | | | | | |
| | | | | | | |
| | | | | | | |
| |________| | | |________| |
|____________| |____________|
Still flat, so lets try and make the inner square appear deeper in the
picture by making it further apart than the outer one -
____________ ____________
| ________ | | ________ |
|| | | | | | |
|| | | | | | |
|| | | | | | |
|| | | | | | |
||________| | | |________| |
|____________| |____________|
Now you get the feeling of looking into a pit, so let's add some more
squares -
____________ ____________
| ________ | | ________ |
|| ____ | | | | ____ | |
|| | | | | | | | || |
|| |[] | | | | | | [] || |
|| |____| | | | | |____|| |
||________| | | |________| |
|____________| |____________|
Now you have a reasonably convincing lift (elevator) shaft. Why the
stagger in placing the squares? Personal opinion. This is how the picture
looks if you only move the squares from one image -
____________ ____________
| ________ | | ________ |
|| ____ | | | | ____ | |
||| | | | | | | | | |
|||[] | | | | | | [] | | |
|||____| | | | | |____| | |
||________| | | |________| |
|____________| |____________|
Notice how the shaft now seems tilted to the left? (Did you just catch
yourself shifting your head to the right? Convincing isn't it?!!) If I am
drawing a double-image stereogram, I try to make changes to the layers on
both the left and right images, otherwise one of the images becomes very
distorted when compared to the other. It also makes for a more centred 3D
effect.
Still here? You are keen, aren't you?!! ;-)
Well this concludes the sections on the basic drawing techniques, the
next section lists some of the common problems that arise when drawing
ster...
