Chaoscope Manual

Previous: Attractors 3. Rendering modes Next: Interface

 

3.1 Gas

 

The Gas rendering method, as well as the next three rendering modes, is based on pixel accumulation : after each iteration, the pixel value corresponding to the current orbit position is incremented, i.e. the pixel is brightened, just like a crystal on a photographic film being hit by a photon. When the image is updated, all the pixel values are normalised then Brightness and Gamma settings are applied.
The higher the number of iterations, the sharper the attractor rendering will be. With the default 640 by 480 image size, 1,000,000 iterations will be necessary to get a clear idea of the attractor features. Subsequent iterations will reduce chaos induced noise and will enhance details.


Gas rendering after various number of iterations :
104 105 106 107 108

Once the image is rendered, two parameters can be adjusted to improve the rendering quality of the attractor. These parameters are :
Brightness : Similar to the brightness setting of a monitor, it's a linear multiplication factor. The default value is 2 for Gas and Liquid methods, 4 for Light and Plasma. It may need to be lowered for attractors with a high fractal dimension. The Brightness parameter is common to all the accumulation rendering methods (Gas, Liquid, Light and Plasma).


Gas rendering with different Brightness values :
1.0 1.5 2.0 2.5 3.0

Gamma : Monitors, especially old CRTs, don't display brightness intensities linearly. For instance, a mid-gray at 50% of absolute luminosity will appear darker than it should on a screen (i.e. 40% of apparent luminosity). As a result, the dim features of an attractor would be hardly noticeable if the Gamma correction wasn't applied to the rendered image. It also helps brightening areas of the attractor with low orbit hits. As a side effect, colours tend to lose their saturation when the Gamma value is high. The default Gamma value is 2.5 for Gas and Liquid methods, 2 for Light and Plasma, 1 for Solid. The Gamma parameter is common to all the rendering methods.


Gas rendering with different Gamma values :
1.0 1.5 2.0 2.5 3.0

Gas is the fastest rendering mode. It can be used as an improved preview, before going for a more complex rendering method.

3.2 Liquid

 
As the basic accumulation algorithm the way it was implemented in Chaoscope lacks of natural visual clues like haze and perspective, it can be difficult at times to "read" the shape of a static convoluted attractor. To make it easier, the Liquid rendering method adds depth and opacity to the Gas rendering through the use of a z-buffer.

3.3 Light

 

The Light rendering mode is a coloured version of the Gas rendering mode. The colour is obtained by adding two different gradients.
The first gradient, a light spectrum by default, depends on the distance between two successive orbit positions, or what can be called the "orbit speed". A reddish tint denotes a slow orbit and is usually located in the centre of the attractor. Purple shades denote a fast orbit and are usually located at the periphery of the attractor.
The second gradient, which goes from black to gray by default, is based on the angle formed between three successive orbit positions. The sharper the angle is the lighter the pixel will be.
Different gradients may be loaded, as described in the Interface chapter. Three examples of the gradient arithmetic are shown below. The result obtained will be hard to predict at first, so it is a good idea to start experimenting with simple two-colors gradients, like those provided with the program.


Light rendering with different gradients
speed gradient   angle gradient   result

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3.4 Plasma

 
The Plasma rendering mode is similar to Light rendering with added opacity.

3.5 Solid

 

The Solid mode uses the same tools as the Liquid mode, an accumulation buffer and a z-buffer, but renders them differently. The accumulation buffer is used for transparency and the z-buffer is rendered using a ray-tracing-like lighting method which includes specular highlights and shadows. Once the image is rendered, two parameters specific to the Solid method can be adjusted. These parameters are :
Opacity : This is the transparency level of the attractor and shadows. The default value is 8.


Solid rendering with different Opacity values :
2 4 8 16 32

Roughness : This parameter sets the size of the specular highlights on the attractor. The default value is 0.008.

Solid rendering with different Roughness values :
0.001
0.004
0.008
0.016
0.064

Notes for the version 0.2 :

  • Control over colours and lamps is not implemented yet.

 

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