# The Online POV-Ray Tutorial

## Glossary / Index

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

## A

Adaptive: used to specify the level of adaptive sampling done with area lights. Adaptive sampling is a method of speeding up lengthy shadow calculations by only checking parts of the light for visibility. (Language Reference)

Agate: a pigment which has very swirly and turbulent bands of color. (Language Reference)

Ambient: in POV-Ray, an arbitrary amount of light added to an object to simulate the effects of ambient light. (Language Reference) (Exploration Tool)

Ambient light: light so scattered from various objects that no discernable source is evident. See ambient.

Area Light: a type of light source which is used to create shadows with soft edges, instead of those with the usual hard, well defined edges. (Language Reference)

Attenuate: to decrease in intensity with distance; usually referring to a light source.

Attribute: a property of an object; e.g. red.

Axis: a line of reference in a coodinate system.

## B

Background: the POV-Ray keyword determining what color will be assigned to a light ray that does not intersect with any object. By default, this is black. (Language Reference)

Bicubic Patch: a complex mathematical object which can be used to describe an smooth surface in space. POV-Ray uses triangles to approximate the surface. (Tutorial) (Language Reference)

Blob: another complex mathematical object which can be used to create organic and, well, blobby (for lack of a better way to describe them) objects. (Tutorial) (Language Referece)

Bounds: a simple object which surrounds a more complex one. When tracing, POV-Ray first does intersection tests against the simple bounding object. If the ray does not intersect the bounding object, it does not intersect the complex one (since the complex one is entirely inside the simple one). Thus, POV-Ray doesn't have to perform a lengthy test with the complex object. The bounded_by statement is used to assign bounds to an object. Automatic bounding objects is controlled with a command-line parameter. (Command-line Parameter Reference)

Bounded By: this statement can be used to assign a bounding object to any other object. (Language Reference)

Box: a three-dimensional geometric object that can be though of as a mathematically perfect... well, box. (Language Reference)

Bozo: a pigment which consists of splotches and swirls of color. (Language Reference)

Brilliance: in POV-Ray, an attribute that affects the angle between incoming light rays and an object; controls how polished or metallic the object seems. (Language Reference) (Exploration Tool)

Bump Map: a normal modifier which allows you to map a pattern of bumps around an object. The pattern of bumps is specified with an image. (Language Reference)

Bumps: a normal modifier which gives an object the appearance of having a bumpy surface. Note that this does not actually change the surface, just how it looks. (Language Reference) (Exploration Tool)

## C

Camera: the object which defines how you want to look at the scene. (Tutorial) (Language Reference)

Checker: a pigment which consists of alternating blocks of color. (Language Reference)

Clipped By: the clipped_by statement allows you clip away parts of an object. (Language Reference)

Clipping: refers to the use of one object to trim away parts of another. It is similar in function to intersection, except clipping shows an object's hollow interior. The clipped_by statement can be used to assign a clipping object to another object.

Clock: a built-in variable you can use to create simple animations. Its value is set by command-line parameter. (Language Reference) (Command-line Reference)

Color: used to set the color of any number of things, including objects and light sources. (Tutorial) (Language Reference)

Color Map: a list of colors that is used by many pigments to color an object. The default color map is a blend from black to white. (Language Reference)

Comment: a section of source code that is ignored by POV-Ray; used for including human text in source code files to improve clarity. (Tutorial) (Language Reference)

Cone:a three-dimensional geometric object that can be thought of as a perfect, well, ice-cream cone (minus the ice cream, of course). POV-Ray also lets you easily create cone that have their points chopped off, as well. (Language Reference)

Coordinates: a set of numbers specifying a point on a coordinate system. In POV-Ray, always in vector form. (Tutorial)

Coordinate system: a mathematical system of describing absolute positions in terms of distance (and direction) from a given point. (Tutorial)

Crand: in POV-Ray, used to simulate roughness or graininess on an object. (Language Reference) (Exploration Tool)

CSG: Constructive Solid Geometry; a technique of combining simple objects into much more complex ones. CSG can be used to group objects together (union and merge), or use objects to carve away parts of other objects (difference and intersection). (Tutorial) (Language Reference)

Cubic: A third-order polynomial object; i.e. a polynomial in which the highest power a variable is raised to is 3. (Tutorial) (Language Reference)

Cylinder: A cone with equal radii throughout. (Language Reference)

## D

#declare: a POV-Ray directive which allows you to assign a name to an object, texture, or just about anything else that can exist. You can also declare constant vectors and floats. Once you have this name, you can easily create multiple copies of the object with only a minimum of extra typing. (Tutorial) (Language Reference)

#default: this statement allows you to change the initial texture on an object. You can declare a default pigment (normally black), a default finish (normally unpolished), and a default normal (normally flat). (Language Reference)

Degree: a unit of angle measurement. 0 degrees corresponds to no tilt; 180 degrees corresponds to a half-turn; 360 degrees corresponds to a full turn. POV-Ray uses degrees whenever angles are required. Degrees above 360 and below 0 are valid, but are mapped back to between 0 and 360.

Dents: a normal modifier which makes an object look like a gorilla had at it with a sledgehammer. The amount of denting can be adjusted between "baby gorilla" and "psychopathic gorilla". (Language Reference) (Exploration Tool)

Difference: a CSG statement used to take an object and carve different shapes out of it. Really, a difference is just an intersection with some of the objects inverted. (Tutorial) (Language Reference)

Diffuse: in POV-Ray, an attribute that controls how much of an object's color comess from direct light. (Language Reference) (Exploration Tool)

Disc: a two dimensional object which is basically a filled-in circle. You can also create discs with holes in the center. (Language Reference)

## E

Eggplant: a vegetable (well, fruit technically) which insures that have something in the "E" category of this glossary. See kumquat.

## F

Filter: an aspect of a color which defines how much light it transmits. (Tutorial) (Language Reference)

Finish: in POV-Ray, how objects interact with light; e.g. reflectivity, refractivity, roughness. (Language Reference) (Tutorial) (Exploration Tool)

Finite Primitive: a primitive in POV-Ray with well-defined limits; i.e. no component deals with infinity. See also infinite primitive. (Language Reference)

Float: see floating point.

Floating Point: a real number.

Fog: used to add colored mist to a scene. Using small amounts of fog can greatly enhance the realism on nearly any scene. (Language Reference)

Frequency: a modifier for certain pigments and certain normals. With pigments, it controls how many times the color map is cycled through in a given "distance". With ripples and waves it controls the density of the waves. (Language Reference)

## G

GIF: an image stored in CompuServe's Graphical Interchange Format. GIFs support 256 colors and a number of other features. All in all, they are a good general purpose image format and are popular because of their good compression system and short decompression time..

Gradient: a pigment which consists of parallel planes of color. (Tutorial) (Language Reference)

Granite: a pigment which consists of spots of on color surrounded by bands of other colors. When used with the proper color map, it can create a very convincing stone texture. (Language Reference)

## H

Height Field: a surface created from an image file which basically defines a mesh of triangles in space. The height of each individual triangle is defined by the color of the pixel in the corresponding location in the source image. This is the easiest and least painful way to create mountains. (Language Reference)

Hexagon: a pigment which consists of hexagonal cylinders of color running parallel to the y-axis of the space. (Language Reference)

## I

Icosahedron: a three dimensional geometric shape with 20 faces, all of which are equilateral triangles. POV-Ray doesn't come with a built in facility to create icosahedra, but there's an example with the triangles in the Language Reference.

Image: a computer term for a displayable file. Generated by POV-Ray from source code files.

Image Map: a technique for wrapping an image around an object. Image mapping is perfect for coloring an object when the standard fare of pigments doesn't contain exactly what you need. (Language Reference)

#include: a directive which tells POV-Ray to read the specified file as if its contents were actually part of the current file. It's very useful for creating libraries of objects or textures. (Tutorial) (Language Reference)

Index of Refraction: how much a translucent object refracts light rays passing through it. (Language Reference) (Exploration Tool)

Infinite Primitive: A primitive in POV-Ray which contains elements dealing with infinity; e.g. a plane. See also finite primitive.

Intersection: a CSG statement which is used to make a new object out of the regions that are inside two or more other objects. It's similar to clipped_by, except intersections don't show a hollow interior. (Tutorial) (Language Reference)

Inverse: a keyword which tells POV-Ray to switch an object's "inside" and "outside". The only time inside and outside of an object matter is when it's in a CSG object or if it's clipping another object. (Tutorial) (Language Reference)

## J

Jitter: refers to random jostling of things. When applied to area lights is causes the lights to be shaken up a bit to prevent shadow bands from forming. With anti-aliasing, it bumps the extra rays around a bit, which breaks up edges. (Language Reference) (Command Line Reference)

## K

Kumquat: an orange-like fruit with an edible rind and a bitter pulp. Note that the only connection with POV-Ray is that it puts something in the "K" section. See eggplant.

## L

Leopard: a pigment which consists of regularly spaced spots of color, like a leopard's coat. Well, it would have to be a very geometric leopard, but that's the basic idea. (Language Reference)

Light ray: an imaginary geometric line describing the path of light as it leaves the light source.

Light source: an object that emits light. See also point light source. (Tutorial) (Language Reference)

## M

Mandel: a pigment which paints the famous Mandelbrot fractal onto an object. Surprisingly, this is not very time consuming for all the extra calculation that must be done. (Language Reference)

Marble: a pigment which is a variation on the gradient theme. Marble also creates parallel planes of color, but uses the color map in a different fashion. With some turbulence it can create a very good looking marble texture. (Tutorial) (Language Reference)

Material Map: a method for mapping complete textures around objects. Material maps use images as templates to do a sort of "paint-by-numbers" operation on an object. Material maps are very powerful for creating exciting textures. (Language Reference)

Merge: a type of CSG which is very similar to a union. However, a merge takes the resulting object and removes an internal surfaces. This is primarily useful on transparent objects, where any internal surfaces would be visible (bad). (Tutorial) (Language Reference)

Modeller: a program that provides a visual interface to creating scenes in POV-Ray; often extremely useful for large scenes in which mental visualization ccan be tricky. (Resource Library)

## N

Near-photorealistic: obviously not taken from a physical camera (but not blatantly so)

Normal: in POV-Ray, surface effects simulated on objects by manipulation of light rays. (Language Reference) (Tutorial) (Exploration Tool)

## O

Object: a thing in space. Objects are what you see when you render a scene. Examples of objects are spheres, boxes, and CSG objects. (Language Reference)

Onion: a pigment which consists of concentric spheres of color, like the layers of skin on an onion. (Language Reference)

Origin: the center of a coordinate system. (Tutorial).

## P

Phase: a keyword which modifies pigments and some normals. With pigments, it controls where the pigment begins when it looks at the color map. With ripples and waves it controls the position of the waves. (Language Reference)

Phong: in POV-Ray, a bright highlight on an object caused by light rays hitting directly from a light source. (Language Reference) (Tutorial) (Exploration Tool)

Pigment: in POV-Ray, how colors or patterns of colors are assigned to an object. (Language Reference) (Tutorial)

Pixel: abbreviation for picture element. One of the thousands of tiny "dots" that serve to make up the display portion of a computer screen.

Point light source: an infinitly-small light-emitting point. In POV-Ray, the simplest type of light source: invisible, non-attenuating, fast. (Language Reference) (Tutorial)

Primitive: one of the basic building blocks of all objects in POV-Ray. Examples of primitives include boxes, cones, and cylinders. (Tutorial)

## Q

Quadric: A second-order polynomial object; i.e. a polynomial in which the highest power a variable is raised to is 2. (Language Reference)

Quartic: A fourth-order polynomial object; i.e. a polynomial in which the highest power a variable is raised to is 4. (Tutorial) HREF="language/iobject.html#quartic">Language Reference)

## R

Radial: a pigment which takes the color map and wraps it around the y-axis. (Language Reference)

Ray-tracing: the process of mathematically generating near-photorealistic images form a given description of a scene or object via geometrical modeling of light rays. (Tutorial)

Real number: a number between positive and negative infinity that does not have any imaginary components (an imaginary component is in terms of i, or the square root of -1); the type of number that POV-Ray works with.

Reflect: the process in which a light ray bounces off an object and continues travelling. (Tutorial)

Reflection: in POV-Ray, an attribute which controls how much an object will reflect its surroundings. (Language Reference) (Tutorial) (Exploration Tool)

Refract: the process in which a light ray is bent slightly when entering a translucent object.(Tutorial)

Refraction: a keyword which tells POV-Ray to refract light that is being transmitted by an object. You also need to specify an index of refraction. (Language Reference)

Ripples: a normal modifier which makes the surface appear like a lake into which a stone was thrown. It creates nice, cirlcular ripples which originate from the origin. (Tutorial) (Language Reference) (Exploration Tool)

Rotate: a transformation which revolves an object around an axis of the space. (Tutorial) (Language Reference)

## S

Scale: a transformation which changes the size of an object. (Tutorial) (Language Reference)

Software: a set of instructions executed by a computer in the form of a program.

Source code: the human-generated code given to POV-Ray to be converted into an image.

Specular: in POV-Ray, a highlight similar to phong but more accurate, as far as physical laws are concerned. (Language Reference) (Exploration Tool)

Sphere: a three-dimensional geometric object that can be thought of as a perfectly round ball. (Tutorial) (Language Reference)

Spotlight: a type of light source which only emits light in a certain direction. (Language Reference)

Spotted: a pigment which is identical to bozo, except it doesn't respond to turbulence. (Language Reference)

## T

Targa: an image stored in the TrueVision Targa format. Targas are versatile and easy to use, and can support 24-bit color. This makes them a good choice for POV-Ray output (see the F command line parameter). Their only drawback is their size, as POV-Ray outputs them in an uncompressed format. See also GIF.

Texture: the texture of an object defines how it looks. It's one thing to have a sphere. It's another to have a striped, bumpy, reflective sphere. A texture is composed of a pigment, a finish, and a normal. (Tutorial) (Language Reference)

Torus: the mathematical name for a doughnut or ring shape. Technically, this is a quartic shape, but it's so useful that POV-Ray authors created an easy way to define one. (Language Reference)

Translate: a transformation which moves an object to a new location. (Tutorial) (Language Reference)

Translucent: able to let light pass though.

Triangle: a two dimesional object which has three vertices and three sides. Exactly what you'd expect from a triangle. (Tutorial) (Language Reference)

Turbulence: a pigment and normal modifier which can be used to stir up a pattern. (Language Reference)

## U

Union: a CSG object which takes a number of objects and combines them together into one. (Tutorial) (Language Reference)

## V

Vector: a set of related numbers. In POV-Ray, enclosed with angle braces, such as <0,0>.(Tutorial)

## W

Waves: a normal modifier which creates waves on the surface of an object. Waves are similar to ripples, except waves are not evenly spaced. (Language Reference) (Exploration Tool)

White space: the computer term referring to all "invisible" characters -- spaces, tab characters, new line characters, etc.

Wood: a pigment which consists of concentric cylinders of color, kind of like growth rings in a tree. (Language Reference)

Wrinkles: a normal modifier which makes a surface appear like it had been wadded up and then stretched back out again. Either that, or left out in the sun too long. (Language Reference) (Exploration Tool)

## X

X: a built-in vector (actually x, as far as case is concerned) with the value <1, 0, 0>.

## Y

Y: a built-in vector (actually y, as far as case is concerned) with the value <0, 1, 0>.

## Z

Z: a built-in vector (actually z, as far as case is concerned) with the value <0, 0, 1>.

The Online POV-Ray Tutorial © 1996 The Online POV-Ray Tutorial ThinkQuest Team