Glossary 33
average colors for inserted pixels). Horizontal interpolation is relatively easy to perform, since the pixels are drawn to the screen in lines. Vertical interpolation is more difficult and requires a complete pixel line to be buffered.
KMIP mapping – In MIP mapping a number of textures are assigned to an object depending on distance. The representation of the object becomes more detailed as the observer approaches the object.
KMultifrequency/Multisync monitor – A monitor that can be operated at various hori- zontal scan frequencies, or that automatically adapts itself to different video signals (resolu- tions).
KOpenGL – 3D software interface (3D API). E.g. implemented in Windows NT and avail- able for Windows 95. Based on Iris GL from Sil- icon Graphics and licensed from Microsoft.
KPage Flipping – The image generated in the ➞back buffer is displayed
KPCI bus – Abbreviation of Peripheral Compo- nent Interconnect Bus. An advanced bus sys- tem, i.e. a system of parallel data lines to transfer information between individual system components, especially to expansion boards.
KPhong shading – ➞ 'Shading'.
KPixel – Picture element. Dot in the image.
K Pixel frequency – Pixel clock frequency (number of pixels drawn per second in MHz).
KPrimitive – Simple, polygonal geometrical object, such as a triangle. 3D landscapes are generally broken down into triangles.
KRAM – Abbreviation of Random Access Mem- ory. Chip memory of a computer or expansion board that can be read from and written to (unlike ROM = Read Only Memory).
KRAMDAC – The RAMDAC converts the digital signals to analog signals on a graphics board. VGA monitors are only capable of processing analog signals.
KRealColor – RealColor normally designates a
KRefresh rate – or image refresh frequency (in Hz) indicates how many times per second an image on the monitor is refreshed.
KRendering – Process for calculating the repre- sentation of a 3D scene, in which the position and color of each point in space is determined. The depth information is held in the ➞Z buffer, the color and size information is held in the ➞frame buffer.
KResolution – The number of pixels in horizon- tal and vertical direction on the screen, for example 640 horizontal by 480 vertical pixels (640 x 480).
KRGB – Color information is saved in the Red/ Green/Blue color format.
KROM – Abbreviation of Read Only Memory. Semiconductor memory that can only be read and not written to.
KShading – Shading or rendering is a way to define the colors on curved surfaces in order to give an object a natural appearance. To achieve this, the surfaces are subdivided into many small triangles. The three most impor- tant 3D shading methods differ in the algorithm used to apply colors to these triangles:
Flat shading: the triangles are uniformly col- ored.
Gouraud shading: The color shades on a trian- gle are calculated by interpolating the vertex colors, resulting in a smooth appearance of the surface.
Phong shading: the color shades on a triangle