Here is a glossary of graphics terms that you might find useful when using CrystalGraphics' products. Please contact the marketing department if there are other terms that should be included.

3D Geometry - Traditional 2D draw and 2D paint programs constrain you to working within the height (Y) and width (X) of the page. But 3D applications also use depth (Z).

Try thinking of the concept in terms of a racquetball in an enclosed court. Bouncing the ball straight up and down uses the Y direction; side-to-side uses the X direction, and smashing the ball with all your might against the service wall vents your frustration in the Z direction.

3D Object - A closed arrangement of polygons that make up a three-dimensional form, such as a cube or sphere. For example, a cube is made up of six square polygons and a sphere is made up of an arrangement of polygons of varying sizes and shapes.

Aliasing - is the staircase or "jaggy" phenomenon brought about by the limitations of working with pixels. Because pixels are distinct points, smooth curves and diagonal lines are not possible.

Alpha Channel - carries transparency information. If your alpha channel has only one bit (i.e. the 16th bit in a 16-bit file), it can only tell if transparency is on or off. If your alpha channel has more than one bit (i.e. the last 8 bits in a 32-bit file), it can designate various levels of transparency. Alpha channels are used in many of the Materials features, such as all mapping and matting. Typically, a high value represents opacity, and a low value represents transparency.

Ambient Light - designates the overall lighting of your scene. The ambient light governs the darkness (or lightness) levels on objects in your model. When the ambient light setting is a light color, the side of your object that is opposite the light source(s) appears lighter. Conversely, when the ambient light is set as a darker color, i.e. black, the side of your object that is opposite the light source(s) appears darker. If you set the ambient light too high (i.e. white), your objects may appear flat. However, don't set the ambient light too dark because your objects may not be easily visible, especially if the objects already have a dark color assigned to them.

Anti-aliasing - reduces the staircase (jaggy) effect that is common along the edges of a polygon. Visually, anti-aliasing is most helpful on low resolution monitors. Anti-aliasing uses blended colors or shades of gray for the pixels along the jagged line. This blended color is a mixture of the object's color/shading and the background color/shading.

Attributes - are the color and material settings you apply to objects. Examples of material attributes are: transparency, roughness, shininess, shading, and faceting.

Axes - define the three dimensions of the universe (X, Y and Z). The X axis represents the horizontal plane; if you move an object on the X axis, you are moving it left or right. The Y axis represents the vertical plane; if you move an object on the Y axis, you are moving it up or down. The Z axis represents the third dimension which gives objects depth; if you move an object on the Z axis, you are moving it closer or farther away from you.

Bevel - the process of going from a 2D object to 3D. Bevel refers to the set of angle planes used to create a 3D surface.

Fast Render - provides much more visual information about objects than wireframe rendering, but takes longer. Fast rendering calculates the color and shading to show each object as a solid, colored object created from polygons. Therefore, a spherical object would appear faceted. Lighting, shading, and texture mapping attributes are displayed. Reflection mapping attributes are not. Fast rendered objects tend to have jagged edges because this rendering method does not use anti-aliasing algorithms. While Fast Render is slower than Wireframe rendering, it is considerably faster than Full Render.

Frame - the working area of a scene, bounded by lines representing the scene's aspect ratio.

Full Render - produces the best results, but it is the slowest rendering method. When a scene is full rendered, the computer takes into account the lighting and then calculates the color, shading, and mapping (both reflection and texture) for each object in the scene. Images full rendered with Flying Fonts Pro have a smoothly shaded, almost photo-realistic quality. And because Full Render applies anti-aliasing, objects have clean, sharp edges.

Gouraud Shading - (which is the shading method used when FastRendering) determines the color value for all the vertices of a polygon. The color is then gradated between the vertices. The color of a Gouraud shaded object is based on the color of the object's polygons, and the color, position and intensity of the light sources.

Image Gallery - is an area of memory where pictures are loaded so they can be used as maps. Before you can use an image for anything, it must be loaded into the Image Gallery first. (Applies to DOS products only.)

Metallic Shading - (which is applied when you choose a metallic material) changes the reflective highlights on your object to more closely match the normal reflective attributes of metal objects by changing the color of the reflected light to the color of the object.

Models - save the geometry of your object and the lighting information. Objects within the model can be rearranged, colored and modified.

Omni Lights - are the equivalent of real-world light sources (i.e. light bulbs). Their light emanates from a point of origin and only illuminates the sides of objects that face the light source.

Open GL - allows your work to display on screen as fully shaded objects rather than wireframe format. Open GL shading is an approximation of the final output quality and it's real time providing you have Open GL compliant hardware). With Open GL you see a rendered image at all times.

Phong Shading - (which is used when FullRendering) calculates all vertices of an object as well as the color value at every pixel between. Phong shading creates the most realistic color and image quality when your model is rendered.

Pixels - or picture elements are the separate units of color which make up an image on your screen. The screen is made up of many pixels (the exact number of pixels depends on the resolution of your monitor). Each pixel is either entirely colored or not. You cannot partially color a pixel. Through the use of pixels, you can neither create a truly curved object nor diagonal lines. However, you can come extremely close through the use of anti-aliasing techniques.

"PLAYMVY" - is the movie playback utility that only comes with Crystal DOS products. It uses extended memory and gives you excellent control over playback. PLAYMVY works well as a stand-alone presentation package for your animations, providing frame-by-frame control when showing your movies. And you can freely distribute PLAYMVY along with your animations, so non-Crystal users can view your work.

Polygons - are closed arrangements of lines that make two-dimensional forms, such as squares and octagons. Polygons are two-dimensional, but they are the building blocks from which all three-dimensional objects are made. For example, a cube is made of six square polygons. Polygon comes from the Greek, meaning "many angles."


Raster Images - Paint and photo-retouching programs are generally raster-based. A raster-based graphics program creates images by controlling the color of every pixel on the screen.

This type of graphics program provides excellent control when creating images. However, creating images with realistic looking perspective and shading can be difficult and time-consuming.

Another limitation of raster-based graphics programs is that creating different views of the same scene (from a different angle, for example), requires the creation of entirely new pictures.

Raster-based image files are usually saved in the TIF, BMP, or PCX file formats.

Reflection Mapping - applies an image onto an object to create the appearance of a reflection. For instance, if you are looking at a spinning gold ball suspended from a string, you will always see your face reflected in the ball back at you.

Rendering - adds shading, highlights, color and texture to a model to create the picture. CrystalGraphics' DOS products include four styles of rendering: WireFrame, QuickView, FastRender, and FullRender.

  1. WireFrame only gives the basic color information and the outline of objects.
  2. QuickView adds more complex color, shading and highlight information to a model, but it only does this on a polygon-by-polygon basis, so even round objects like spheres will seem faceted. QuickView is slower than WireFrame but much faster than FastRender.
  3. FastRender uses Gouraud shading.
  4. FullRender is the most sophisticated of rendering techniques, but it is also the slowest rendering method. FullRender draws the model in its most complex form, including shadows, texture maps, and so forth.

Splines - are mathematical representations of curves. Splines are used to create objects such as irregular curves, which can't realistically be represented by straight lines.

Spotlight - is a directional light, meaning that you can aim it at an object, or a specific part of an object. You do this by aiming the spotlight's cone where you want the light to appear. The cone of light is infinite, even though the graphical representation of the cone is finite. This means that the cone does not have to touch the object that you are lighting.

SuperBlack - sets the background to pure black, and all other blacks in the model to a shade slightly lighter than pure black. This allows video compositing keyed to black, without risk of the video image appearing on objects or maps that are the same color as the background.

Texture Mapping - is when you apply a picture to an object. One type of mapping, Project, applies the image to the object in the same way that a slide is projected onto a screen.

Uniform Shading - (which is the shading technique used when QuickView rendering) produces no variation in color across a polygon. A uniform color creates a very flat or faceted appearance.

Vector Models - Rather than controlling the placement and shade/color of every pixel, vector-based programs mathematically create two-dimensional objects.

This type of graphics program allows the creation of very detailed images with smooth curves. However, because these programs do not allow pixel-by-pixel editing, it is difficult to create images with smoothly shaded objects. Without realistic shading, it becomes difficult to create a three-dimensional effect.

As with raster-based programs, vector-based graphics programs require the creation of an entirely new picture when creating another view of the same scene.

Vector-based, 2D illustration programs usually create image files in the AI, EPS, or WGM file formats.


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