The filtration is anisotropic. Practical use of extensions: anisotropic filtering

Anisotropic filtering is one such element in the development of modern graphics, which forces many users to speculate on how different image enhancement technologies for users have become available today.

After all, do not hide the fact that gamers today are so important to the highest quality three-dimensional graphics, and they are today are virtually the only consumers of all sorts of new technologies in the field of video cards. After all, a high-power accelerator at the moment can be required only if you need to run some game of the latest generation, in which there is a really demanding engine, operating with the most complex shaders of different versions.

What kind of cards are there?

Doing some kind of advanced engine in our time is a serious waste of money. And at the same time a significant risk. Such methods are used only by high-budget projects with large-scale advertising, which in advance, before the exit, are sure that the game will be swept away from the shelves. It should also be noted that recently, special attention is paid to "politics" regarding modern game engines, because in the field of gaming, there has long been a policy that prefers to take into account the interests of two leading companies in the field of graphics processors - NVIDIA and ATI.

The companies compete with each other for a long time, and in fact there are no prospects that this confrontation will end in the near future, but consumers are only at hand. Now it is not enough just to develop a really high-quality engine, it is also necessary to enlist the support of one of the manufacturers, who even created their own partner programs for igrodel players.

And the graphics are growing and growing ...

It is quite difficult to make an absolute revolution in the sphere of 3D graphics engines, as a result of which such upheavals occur relatively rarely. However, of course, the image quality improves periodically over time and, oddly enough, it happens just under the output of a certain "selling" game like Crysis.

It is on the basis of anisotropic filtering, as well as the so-called antialiasing, that today we are releasing a huge number of different drivers for each manufacturer's video cards, with each company using its own approach and policy regarding this optimization, which is often not just for all users.

What is anisotropic filtering?

Filtering anisotropic is a specialized way of improving textures on surfaces that are at a certain angle relative to the camera. Just like trilinear or bilinear, anisotropic allows completely eliminating aliasing on different surfaces, but at the same time introduces a minimum of blurring, so that the limiting detail of the image is preserved.

It is worth noting the fact that anisotropic filtering in games is realized through a complex calculation, so ensuring a relatively small "gluttony" of this setting in games has been observed only since 2004.

In order to understand what anisotropic filtration is, you need to have some basic knowledge in this area. Of course, today every user perfectly understands that the image on the screen is made up of a huge number of different pixels, the number of which directly depends on the resolution. In order to display the image on the screen, the video card must be processed color of each pixel.

Operating principle

Selects a specific texture that corresponds to the resolution that is across the direction of the view. After this, several texels are taken along the viewing direction, after which the averaging of their colors is carried out.

Since there can be more than one million pixels on the screen, and each texel is at least 32 bits in this case, anisotropic filtering in games requires an incredibly large bandwidth of the video card, which is not provided by many even the most modern devices. It is for this reason that such large memory requirements are reduced by the use of caching, as well as specialized technologies for compressing textures.

How it works?

Determination of the color of pixels is carried out by imposing on the polygons texture images consisting of pixels of a two-dimensional image - texels, which are superimposed on a 3D surface. The main dilemma in this case is which texels will determine the color of the pixel on the screen. In order to understand more deeply the feature of filtering anisotropic, one must imagine that your screen is a large plate with a huge number of various holes, each of which is a pixel.

To determine the color of a pixel on any three-dimensional scene that is behind this plate, it's enough to just look into the corresponding hole. Now let's imagine that a ray of light passes through it, then it hits our polygon, and if it is located parallel to the place of its entrance, then a round light spot will turn out. If not, the spot will be somewhat distorted, that is, it will already have the shape of an ellipse. It is polygons that are located in the light spot, and will determine the color of each particular pixel.

Why is it needed?

Many believe that anisotropic filtering is used solely to provide a better image, but in fact it is just the end result, which is provided not only by the filter itself.

When creating an image of a specific texture, programmers are given two levels of texture filtering, which are the minimum and maximum distance filters that determine what specific filtering function will be used in the process of forming a texture image in the event that the camera moves away or approaches it.

For example, you can consider when anisotropic or trilinear filtering is used when approaching, that is, when each texel begins to have large dimensions, and already covers several pixels at the same time. In order to remove the gradation in this situation, filtration will be used. It should be noted that in this situation, this solution is far from optimal, since filtering (anisotropic or trilinear) slightly smears the image. In order to give a more realistic view of the picture, you need to increase the resolution of the texture itself.

What is better to choose?

Of course, any user and simple gamer have a completely logical question. Today, there is trilinear and anisotropic filtering - which is better? In fact, it is better, of course, precisely anisotropic technology. The thing is that trilinear filtering does not correctly calculate the color of each individual texel, and if to speak more accurately, it does not calculate it correctly when it comes to inclined planes. The use of anisotropic technology allows us to supplement the currently used filtration modes by adjusting the angle. In this case, the larger the angle, the higher the realism and quality, which can provide anisotropic filtering of textures. However, at the same time, you need to understand that more card capacity is required to process the data.

How much does it help?

You should not expect that after the inclusion of this function, the three-dimensional graphics will improve fabulously, but at higher angles even a certain blur will be obtained, but in the general result you will get a more realistic picture. In this regard, each for himself independently decides whether he should use this function and how it will be productive for him.

Since this function does not provide a very strong picture quality improvement, those people who try to ensure maximum game performance on not the most powerful computers, are looking for how to disable anisotropic filtering. The exactness of this function is a little incommensurable in comparison with what result it provides, so it is worth considering to disable it in the first place.

Point Sampling

Point Sampling today is the simplest version of how the pixel color is determined. This algorithm is based on the texture image, when selected a single texel, located as close to the center of the light spot. It is easy to guess that this option is far from the most optimal, since the pixel color should be determined simultaneously by several texels, and only one is selected in this case, and the light spot can change its shape, which the algorithm does not take into account.

The main drawback with which such filtering differs is anisotropic, is that with a sufficiently close arrangement to the screen, the number of pixels will increase significantly in comparison with the number of texels, as a result of which the image becomes far less interesting. The so-called block effect is often observed in "ancient" computer games.