Fillrate
Encyclopedia
The term fillrate usually refers to the number of pixels a video card
can render and write to video memory in a second
. In this case, fillrates are given in megapixels per second or in gigapixels per second (in the case of newer cards), and they are obtained by multiplying the number of raster operations (ROPs) by the clock frequency of the graphics processor unit (GPU) of a video card
. However, there is no agreement on how to calculate and report fillrates. Other possible methods are: to multiply the number of texture units by the clock frequency, or to multiply the number of pixel pipelines by the clock frequency.
The results of these multiplications correspond to a theoretical number. The actual fillrate depends on many other factors. In the past, the fillrate has been used as an indicator of performance by video card manufacturers such as ATI
and NVIDIA
, however, the importance of the fillrate as a measurement of performance has declined as the bottleneck in graphics applications has shifted. For example, today, the number of pixel shader units has gained attention.
Scene complexity can be increased by overdrawing, which happens when "an object is drawn to the frame buffer, and then another object (such as a wall) is drawn on top of it, covering it up. The time spent drawing the first object was wasted because it isn't visible." When a sequence of scenes is extremely complex (many pixels have to be drawn for each scene), the frame rate
for the sequence may drop. When designing graphics intensive applications, one can determine whether the application is fillrate-limited by seeing if the frame rate
increases dramatically when the application runs at a lower resolution or in a smaller window.
Video card
A video card, Graphics Card, or Graphics adapter is an expansion card which generates output images to a display. Most video cards offer various functions such as accelerated rendering of 3D scenes and 2D graphics, MPEG-2/MPEG-4 decoding, TV output, or the ability to connect multiple monitors...
can render and write to video memory in a second
Second
The second is a unit of measurement of time, and is the International System of Units base unit of time. It may be measured using a clock....
. In this case, fillrates are given in megapixels per second or in gigapixels per second (in the case of newer cards), and they are obtained by multiplying the number of raster operations (ROPs) by the clock frequency of the graphics processor unit (GPU) of a video card
Video card
A video card, Graphics Card, or Graphics adapter is an expansion card which generates output images to a display. Most video cards offer various functions such as accelerated rendering of 3D scenes and 2D graphics, MPEG-2/MPEG-4 decoding, TV output, or the ability to connect multiple monitors...
. However, there is no agreement on how to calculate and report fillrates. Other possible methods are: to multiply the number of texture units by the clock frequency, or to multiply the number of pixel pipelines by the clock frequency.
The results of these multiplications correspond to a theoretical number. The actual fillrate depends on many other factors. In the past, the fillrate has been used as an indicator of performance by video card manufacturers such as ATI
ATI Technologies
ATI Technologies Inc. was a semiconductor technology corporation based in Markham, Ontario, Canada, that specialized in the development of graphics processing units and chipsets. Founded in 1985 as Array Technologies Inc., the company was listed publicly in 1993 and was acquired by Advanced Micro...
and NVIDIA
NVIDIA
Nvidia is an American global technology company based in Santa Clara, California. Nvidia is best known for its graphics processors . Nvidia and chief rival AMD Graphics Techonologies have dominated the high performance GPU market, pushing other manufacturers to smaller, niche roles...
, however, the importance of the fillrate as a measurement of performance has declined as the bottleneck in graphics applications has shifted. For example, today, the number of pixel shader units has gained attention.
Scene complexity can be increased by overdrawing, which happens when "an object is drawn to the frame buffer, and then another object (such as a wall) is drawn on top of it, covering it up. The time spent drawing the first object was wasted because it isn't visible." When a sequence of scenes is extremely complex (many pixels have to be drawn for each scene), the frame rate
Frame rate
Frame rate is the frequency at which an imaging device produces unique consecutive images called frames. The term applies equally well to computer graphics, video cameras, film cameras, and motion capture systems...
for the sequence may drop. When designing graphics intensive applications, one can determine whether the application is fillrate-limited by seeing if the frame rate
Frame rate
Frame rate is the frequency at which an imaging device produces unique consecutive images called frames. The term applies equally well to computer graphics, video cameras, film cameras, and motion capture systems...
increases dramatically when the application runs at a lower resolution or in a smaller window.