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We all know about mip-mapping. It reduces texture quality when a texture is further away.

Without mip-mapping, a texture appears to "flicker", like the top of the mountain here:

enter image description here

Is there any specific name for it?

I want to write a sentence like "I applied mip-mapping to solve the ___ effect", or "This is known as ___, and occurs when mip-mapping is not used".

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    \$\begingroup\$ Adding a screenshot of what you're talking about would greatly improve the question :) \$\endgroup\$
    – Vaillancourt ♦
    Nov 11, 2015 at 14:08
  • \$\begingroup\$ @AlexandreVaillancourt Thanks for the suggestion - Added. :) \$\endgroup\$
    – joehot200
    Nov 11, 2015 at 16:03

5 Answers 5

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What you're looking for is aliasing. It's little different from aliasing of hard 3d edges drawn on screen. Both come from rendering pixels too strictly, with one color or another. Antialiasing methods like mip-mapping only help blurring the edges so that intermediate colors are rendered. This can be applied to single textures but also to the whole screen.

Note however that mip-mapping is not the only solution to this. You can use other procedural interpolation algorithms too.

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    \$\begingroup\$ "Blurring the edges" is not a good way to describe what happens. This type of antialiasing is about using more samples from the original texture to determine the color of each pixel. Since mip-maps are smaller copies of the original texture, taking a single sample from a mip-map is like taking multiple samples from the original texture. It's also worth noting that mip-maps are only an optimization for rendering performance. You can get the same effect by taking more samples from the original texture when rendering. \$\endgroup\$
    – Roger Dahl
    Nov 11, 2015 at 17:52
  • \$\begingroup\$ @RogerDahl I've never heard of this "taking more samples from the original texture" to replace Mip-mapping. What is it called (so I can google it)? \$\endgroup\$
    – joehot200
    Nov 11, 2015 at 17:59
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    \$\begingroup\$ @joehot200: "Mip-mapping" is just a pre-computation-based optimization for proper downscaling. In general if you're downscaling an image such that one output pixel corresponds to the space covered by N pixels in the source, you need to use at least those N pixels (and maybe more) as input. This is obviously computationally costly. By having pre-computed versions of the source at scales 2^-k for each reasonable value of k, you can cheat and essentially read N pixels all at once. \$\endgroup\$
    – R.. GitHub STOP HELPING ICE
    Nov 11, 2015 at 19:10
  • \$\begingroup\$ Of course it's actually a less-than-ideal approximation and yields some aliasing artifacts. What would be better than having pre-computed 2^-n scaled versions of the source texture would be having pre-computed band-limited versions of it still at full dimensions. This would get you correct sampling, but would of course consume a lot (probably prohibitive) more memory. \$\endgroup\$
    – R.. GitHub STOP HELPING ICE
    Nov 11, 2015 at 19:13
  • \$\begingroup\$ I know some games (especially slightly older ones) even have a slider labeled anti-aliasing. So self-explanatory. \$\endgroup\$
    – Daniel
    Nov 11, 2015 at 19:56
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Aliasing artifacts/moiré patterns

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    \$\begingroup\$ @joehot200 What do you mean, "related"? Aliasing is precisely what mipmapping solves, among other things. Aliasing is the "effect" that occurs. \$\endgroup\$
    – snake5
    Nov 11, 2015 at 11:52
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    \$\begingroup\$ The term "undersampling" arises here too, because your rendering is taking too few samples of the texture to accurately capture its average appearance over the span of the rendered pixel, so slight changes in sample points (eg. small camera moves) result in very different output values (shimmering/sparkling) \$\endgroup\$
    – DMGregory ♦
    Nov 11, 2015 at 14:20
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Is there any specific name for it?

That flicker you are talking about is called in this certain case moiré effect / pattern. It's a form of spatial aliasing as already mentioned in other answers. However, aliasing itself can result in a lot more things than just moiré patterns.

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I have heard the term "popping and boiling" applied to the aliasing you're showing on that mountain in the background. It is not a mathematical term, but it is descriptive. So aliasing would be what you'd write your paper about if you wanted to invent a different fix for the problem and use it to get money (grants, academic promotion). "Popping and boiling" might be what you'd call it in a demo (for VC money).

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I'd just like to add that there's another side-effect of not using mip mapping: Not only will you get the hideous aliasing (see the Nyquist theory for what is going on), you will probably also get a reduction in performance as the texture accesses become incoherent and thrash the memory/cache system of your GPU.

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