Analysis on Anti-sawtooth Technology of 3D games with perfect image quality

 

The perfect picture is no longer far away from us-Analysis of Anti-sawtooth Technology

No matter how perfect the current game screen is, how real the people and environment are, the main way the game screen is made up is still not improved: A frame consists of thousands of pixels. This means that the contour of the polygon is eventually a jagged image. Therefore, the image quality cannot reach the ideal standard unless the "sawtooth" is completely eliminated ". Don't worry, exquisite image quality will be exchanged at the cost of speed, and major graphics card manufacturers have their own unique anti-sawtooth technology, their new graphics acceleration cards all support full-screen anti-aliasing. The perfect picture is far away from us.

Supersampling) 

No matter what kind of anti-aliasing technology is developed on the basis of the Super sampling technology. In the super sampling technology, each pixel in the screen is divided into several sub-pixels, and then processed separately and placed into the buffer zone. After the pixels of the entire frame are placed in the buffer zone, the next operation is performed. The split pixels are filtered or aggregated to generate new pixels according to the template format. During the super sampling period, the image is created at a high resolution and then filtered according to the appropriate template style. (1, 2) If we enable the 4x anti-sawtooth function of gf2 at resolution, the performance of the video card will be equal to that of the 1600x1200 mode. As super sampling consumes a huge amount of system resources, the system performance decreases significantly when the super sampling anti-aliasing function is used.

Multi-Sample)

Multi-sampling adopted by NVIDIA on geforc4is often misunderstood as super sampling technology. In fact, NVIDIA's multi-sampling technology is a form of super sampling technology. The main difference between the multi-sampling adopted by NVIDIA in gefore3/geforce4ti/geforce4 Mx and the super sampling adopted in geforce2 is: the number of sub-pixels processed by the chip when processing the same image is different. If we want a smooth image, we only need to process the polygon edge. NVIDIA has one feature when performing multi-sample: When coloring a pixel, it not only samples its own sub-pixels, you can also sample the sub-pixels of several neighboring pixels at the same time. The image attributes of the adjacent sub-pixels are also included, which affects the color attributes of the pixel. In this way, the number of subpixel samples involved in the calculation also changes from 2 to 5. (3)

When gf3 enables this full-screen anti-sawtooth technique, it feels much smoother on the edge of a polygon than when super sampling is used, but its performance is not obvious. (4, 5) It is recommended that a friend with a video card above gefor2010open it.

Smoothvision)

ATI has its own anti-sawtooth technology-Visual smoothness. This technique uses a jitter sampling table to flexibly control the sampling position changes. In this way, only 8 samples (6) are extracted from each group of 16 samples by controlling the jitter sampling table) it should be said that visual smoothing smoothvision has little advantage over supersampling with super sampling, and the actual effect shown on radeon 8500 is indeed not flattering. When the anti-sawtooth function is enabled, the performance will still decrease. Therefore, radeon 8500 automatically reduces the level of texture details after enabling the anti-aliasing function, thus reducing the throughput of the memory bandwidth. However, the texture quality becomes very bad. (Full screen anti-sawtooth is not enabled on 7 and 8, smoothvision 6x is used on 9 and 10)

Do not worry if you have radeon 8500. We can also use other technologies to make up for this defect: you only need to enable the Al filter to use the filter to improve the texture quality. Radeon 8500 has very low performance loss after enabling heterosexual filtering, but the image quality has improved a lot.

16 times full screen (FAA-16X)

Martox's anti-aliasing Technology in parhelia-512 is significantly better than other companies. This revolutionary method has the lowest impact on the performance of the system, and can achieve the best effect of eliminating sawtooth. For apps that support FAA-16X, parhelia-512 functions soften only the pixels at the triangle edge, and the serrations we see in the game are produced at the edge of the graph, the object will not be seen inside it, and then we can use 16 times of sampling. At the same time, we can keep the clear and sharp pixels inside the object, which achieves the softening effect of the entire image. Generally, the pixel of the edge occupies only a small part of the entire image, so the 16-fold softening of the edge will not reduce the performance too much. (11 parhelia-512 friends, don't open the FAA-16X can lose !)

High resolution instead of anti-sawtooth

In fact, we do not need to only use the anti-sawtooth effect in the video card. We also have a very simple method-to improve resolution. When the resolution reaches a high level, the Sawtooth will become less obvious. For example, when the resolution is increased by a factor in the horizontal direction and B in the vertical direction, the physical pixel size on the display actually decreases, and the pixel area actually decreases by AXB. The amplitude of the Sawtooth is also reduced by a multiple of the same.

To achieve super sampling or 4x multi-sampling, you must double the resolution in both the horizontal and vertical directions (for example, 1600x1200,102x2048 ). When you adjust the resolution of the monitor to the maximum value, you must endure the 60Hz or lower update rate. The performance reduction caused by the anti-sawtooth effect is smaller than improving the resolution, especially when the FAA-16X with parhelia-512 looks more cost-effective. All in all, you can increase the resolution either by enabling full-screen anti-aliasing.
Let's take a scenario of Homeworld: cataclysm as an example to compare it.

At first, the full-screen anti-aliasing was not enabled. The fleet looked vague and poor, and it was difficult to distinguish the types of the fleet units, and the outline of the ship was almost invisible. (12, 13, 14)

Enabling full-screen anti-aliasing is better. Although the entire screen is blurred, it can still identify the shape of the ship. (15, 16, 17)

After the resolution is improved, the entire image is clearer, and the image is clearer than that when the anti-sawtooth effect is enabled. However, the image still has some small serrations at the edge. (18, 19, 20)

Both anti-aliasing and improved resolution provide us with high-quality images. If you select one, it depends on your personal preferences.

Speed vs. Image Quality

The main reason why full-screen anti-sawtooth is not widely used is that this technology will significantly degrade the performance. The higher the sampling factor, the more obvious the performance decline. For example, 2x super sampling causes the performance of the video card to nearly double, 4x is 4 times, and 6X is an astonishing 6 times.
This requires you to learn more about the performance of your video card and select the anti-aliasing factor suitable for your video card performance. If you have a video card like radeon 8500 plus a strong CPU and memory, even if you are running a game at 1024x768/32 bits in heavy smoothvision mode, the speed is still acceptable. For those earlier graphics cards NVIDIA geforce2 MX, powervr/STM kyro/kyro II, SIS 315, etc., because of their own performance is not very high, the video card runs hard in normal mode, in addition, only super sampling is supported. Therefore, after the full-screen anti-sawtooth function is enabled, the performance is greatly reduced. In this case, you can only reduce the resolution to run the game. Think about the X resolution, but what you get is the performance of X and the image quality is not as good as X, in this case, we do not need to enable the anti-sawtooth function. Gaming image quality is always in conflict with FPS. For relatively limited computer performance, the fish and the bear's paw cannot have both sides. In the fierce CS battle, who will calm down to see if the AK corners in the enemy's hands within 2 m on the opposite side are serticate?