Apophysis 3D Revealed

The Case For Apophysis

Apophysis 3D has a setting in the Adjust panel called “Perspective”. If you keep that value, Perspective = 0, you have a unique visual environment for your renders which is NOT available to an ordinary camera in the real world.

This is called Parallel Perspective. In this special case, the environment is parallel which means to obtain stereo image pairs, the camera has to angle towards the subject. The angle between the two views is referred to as the Stereo Angle. To Stereophotographers this might sound like toe-in, but due to the unique circumstances that is not the case.

1. The render camera does not have a distorting lens.
2. Features do NOT change size with distance – perspective lines are parallel
3. The camera’s virtual image-sensor/film-plane is practically infinite – or limited in part by your computer screen and the practical limits in the software as to where fractal flame image data exists.
4. Merely sliding the render camera sidewards does NOT result in a stereo perspective shifting, only a moving of the virtual film plane across the virtual image focal plane. (Virtual because we’re talking about what happens in the computer as the software is rendering based on complex algorithms)

If you introduce Perspective by changing the value in this control to positive (+) values, you cause the more distant features to reduce in visible size for both X and Y as compared to foreground features. The opposite occurs for negative values. Positive or normal perspective can be pleasing in it’s effect because it simulates the real world, but for stereo it can cause those distant features to shift vertically up or down during the effort to move the camera between the two requisite stereo view points.

When it is used in very small increments the difference may be minimal and not cause your image to be unviewable, but it can easily introduce distortion. Distortion causes eye strain when you try to view the stereo results. Eye strain is NOT good! Your goal is to avoid anything that will cause undue eyestrain.

If the perspective effects could be restricted to horizontal shifts with NO vertical (up/down) change, then it would work for stereoscopic image settings. At the moment, this is not possible.

So, the rule is:

• Keep perspective = 0 at all times
• Or, use very small amounts of perspective AND stay very close to a direct side view of the Flame Fractal, ie: Pitch=90 with no other tilting/rotating of the Flame up/down. Perspective is more noticeable as you move away from the direct side view.

The Case for the Ordinary Camera

In stereo photography there is a hardened rule: Never ever use toe-in to capture a stereo image pair.

Explanation – when you view a flower with your eyes, each eye is directed at the flower. So, the intuitive question comes up, why not direct the camera the same way to capture a stereo view of the flower?

The answer is an emphatic NO. It doesn’t work that way!!!!

Here’s why: Normal space involves perspective, or the property of the perceived size of an object getting smaller with distance. A nearby tree seems big, but one a long ways away is tiny. The eyes are very sensitive to this size issue as it’s a key depth perception factor. The flower in your garden may be relatively close to you, but you can perceive that the far side of the flower has a slightly  reduced scale compared to the near side. You may not think about it, but your eye sees this.

So does your camera, plus one more thing. The camera has a lens which causes a small amount of spherical distortion. You can watch it by looking at your viewfinder as you slowly pan a camera from side to side. You’ll notice the edges are being stretched relative to the center of the image view.

If you toe-in your camera for a stereo view the combined perspective effects and the lens distortion cause the two resulting views to be distorted slightly in different directions from each other. Some details in the background will shift vertically up or down relative to the same details elsewhere in the picture. This change is greatest when comparing near foreground and far background features.

One more critical factor makes this process fail for ordinary cameras. If you aim your camera at the flower, the two views converge closer together in front of the flower, converge at the flower and diverge at all points behind the flower. This causes the stereo depth factors as recorded on the picture-pair for parts of the scene that are behind your flower to have reversed depth!

The correct method is to keep the camera aligned in identically the same direction for both pictures, with only a slight non-rotated side shift. This results in the center of the camera’s view remaining parallel for both viewpoints. In this situation the camera lenses are parallel while the scene being recorded has perspective effects.

If you don’t have a background visible behind what you are aiming for and you use toe-in by aiming the camera at your subject for a stereo pair, you will find in some circumstances that you can get acceptable image pairs. The lens distortion still exists but can be smaller than the eye can notice, depending on the scale of your view and how you’re viewing the results. It can work but it’s not recommended. One example where it works is capturing the surface textures of a rocky cliff.