Glossary » V

A vertex is a single point in 3D space whose position is described by an X, Y and Z coordinate. When we talk about polygons, the vertex is the point at which two sides meet, or the “corners”. A triangular polygon therefore has three vertices.

A Vertex Shader handles small programs or instruction sets and applies them to any relevant vertices received through the graphics pipeline. Think of a Vertex Shader as a separate graphics processor designed specifically to allow complex manipulation of the scene geometry. Effects that can be created using Vertex Shaders include lens effects, particle effects, fur, skinning, morphing and much more.

The number of times per second the monitor can draw all the lines over the entire screen. A higher vertical frequency or refresh rate will produce less flicker. See flicker and refresh rate

Also known as Vertical Sync(h) or more commonly V-sync(h). The term Vertical Synchronisation refers to the synchronizing of your video card’s output to your monitor’s vertical refresh rate. When Vertical Synchronisation is enabled your graphics card will hold completed frames in its frame buffer until the monitor has completed drawing the current frame in its entirety. As a result your graphics card’s frame rate can never exceed your monitor’s vertical refresh rate. The advantage to enabling Vertical Synchronisation is that it can reduce a phenomenon known as video tearing.

Video Electronics Standards Association. An association of companies, which cooperate in establishing common standards for video display systems such as display timing, power management and communication protocols between devices.

Is the acronym for Video Graphics Array though the term is quite often misused. Introduced April 2, 1987 by IBM VGA was a standard that indicated your graphics hardware could display 256 colours at a resolution of 320x400, though these days it’s often used wrongly to describe the standard analogue output to which you connect your monitor (VGA Connector).

The speed at which data is received from the graphics card over the monitor’s video amplifier. Higher speeds normally indicate higher resolutions at faster refresh rates and with improved focus and brightness. Measured in MHz.

Video tearing is a phenomenon that often results from disabling V-sync on your graphics hardware. Like your TV a computer monitor draws the screen a line at a time and when V-sync is enabled your graphics card will wait for a signal from your monitor to say it’s completes the current screen draw and is ready for the next frame. With V-sync disabled your graphics card sends completed frames to your monitor no matter what stage it’s at. Let’s imagine your monitor is running at a resolution of 800 x 600. That means your monitor’s electron gun has to illuminate 800 pixels across its width then do the same for 600 lines before a complete screen is drawn. Now let’s imagine your monitor has been sent the data required to draw frame 1 of your game and so it begins to draw at line one and work its way down to line 2 then line 3 and so on. Because V-sync is disabled it may only get to line 300 before your graphics card sends frame 2, at which point your monitor stops working on frame 1 and continues working on frame 2 starting at line 301. The result is that we have two frames being drawn on the same screen, one at the top and another lower down. This may be fine provided the two frames are similar to each other but if the game is fast moving, perhaps a racing game or other fast paced action game it’s quite likely that between frame 1 and frame 2 there has been a significant amount of movement and the two sections simply don’t match up. The horizontal lines that appear where sections of the scene are out of alignment are what’s known as video tearing.

The maximum amount of screen surface onto which the actual picture can be projected. Most manufactures quote sizes approximately one inch less than the diagonal linear measurement, but in practice it is usually less than this. For example, a 17in monitor maybe quoted as having a 16in viewable diagonal, but the ‘actual’ viewable diagonal maybe 15.75in. This has to be physically measured when the unit is on fully warmed up.

This is the approximate, maximum angle at which a user can clearly see the picture projected on an LCD. Moving past this viewing angle results in a noticeable drop in brightness, contrast and colour reproduction. The viewing angle is assessed both horizontally and vertically and is either stated as a total viewing angle (i.e. 160 degrees horizontally and 120 degrees vertically), or as angles from the perpendicular (i.e. 80 degrees left and right, 70 degrees up and 50 degrees down).

Video object. The video data format used by DVD movies

Voice Over Internet Protocol, or more commonly just Voice Over IP. This is a where telephone calls use a LAN or the Internet (any IP-based network) instead of traditional telephone lines.

A Voxel is the name given to a volumetric pixel. Just as a Texel is a pixel to which a texture has been applied, so a Voxel is a pixel to which a 3D texture has been applied.

Virtual Private Network. A connection, or tunnel, between two networks or systems where data encryption and authentication are used to stop anyone ‘eavesdropping’. Often used for secure connections over public networks such as the Internet.

Video Processing Unit. Just like GPU this refers to the actual graphics chip on a card. VPU was a term developed by ATi.