3D Graphic issues when object is far

In many games I played or watched that are 3D, most faraway objects tend to degrade quality or disappear from view. Why does this happen?

It's called LOD, which stands for "Level of Detail". The idea is that drawing any particular object has a certain cost associated with it. There's some CPU cost for figuring out an object is visible and submitting commands to the GPU, there's some shader cost on the GPU for transforming vertices and shading the pixels, and there's bandwidth cost for sampling texures and writing the final resut to the frame buffer. The more you have to do all of that stuff, the longer it takes to render a frame and therfore the lower your framerate. So the point of LOD is to lower the cost for far-away objects, since far-away objects will be in the background which means you no longer need fine details. This might include lowering the polygon count, removing detail textures, not using normal mapping, and using mipmaps (mipmaps are lower-resolution versions of a texture). All of those do a pretty good job of reducing GPU-side costs, but don't remove them completely. And they do nothing for CPU-side costs. So eventually for a game you have to draw a line somewhere and say "things that are X far away just won't be drawn at all". This is why in some games you will see objects fading in, or popping in.

Draw distance. Everything thats on your screen has to be "loaded", and that takes up memory. Its done because there isn't enough memory for said objects to be on screen.Skittles_McGee

It's called LOD, which stands for "Level of Detail". The idea is that drawing any particular object has a certain cost associated with it. There's some CPU cost for figuring out an object is visible and submitting commands to the GPU, there's some shader cost on the GPU for transforming vertices and shading the pixels, and there's bandwidth cost for sampling texures and writing the final resut to the frame buffer. The more you have to do all of that stuff, the longer it takes to render a frame and therfore the lower your framerate. So the point of LOD is to lower the cost for far-away objects, since far-away objects will be in the background which means you no longer need fine details. This might include lowering the polygon count, removing detail textures, not using normal mapping, and using mipmaps (mipmaps are lower-resolution versions of a texture). All of those do a pretty good job of reducing GPU-side costs, but don't remove them completely. And they do nothing for CPU-side costs. So eventually for a game you have to draw a line somewhere and say "things that are X far away just won't be drawn at all". This is why in some games you will see objects fading in, or popping in.

Teufelhuhn

Thank you for your post Teufelhuhn. Nothing more needs to be said.

Draw distance. Everything thats on your screen has to be "loaded", and that takes up memory. Its done because there isn't enough memory for said objects to be on screen.Skittles_McGee

[QUOTE="Skittles_McGee"]Draw distance. Everything thats on your screen has to be "loaded", and that takes up memory. Its done because there isn't enough memory for said objects to be on screen.Teufelhuhn

[QUOTE="Teufelhuhn"]

[QUOTE="Skittles_McGee"]Draw distance. Everything thats on your screen has to be "loaded", and that takes up memory. Its done because there isn't enough memory for said objects to be on screen.Skittles_McGee

[QUOTE="Teufelhuhn"]

[QUOTE="Skittles_McGee"]Draw distance. Everything thats on your screen has to be "loaded", and that takes up memory. Its done because there isn't enough memory for said objects to be on screen.Skittles_McGee

[QUOTE="Skittles_McGee"]

[QUOTE="Teufelhuhn"]

Well you can't really immediately load things (or unload them) the instant they need to be on-screen. Either the game has to load in an entire level (or chunk of a level) into memory all at once, or it has to stream things in well in advance. Usually games that stream will mostly stream textures, and not the geometry so much. This way they can still draw something, and then as the higher mipmaps of a texture come in they can fade in more detail.

Teufelhuhn

oooooh

[QUOTE="Skittles_McGee"]

[QUOTE="Teufelhuhn"]

Well you can't really immediately load things (or unload them) the instant they need to be on-screen. Either the game has to load in an entire level (or chunk of a level) into memory all at once, or it has to stream things in well in advance. Usually games that stream will mostly stream textures, and not the geometry so much. This way they can still draw something, and then as the higher mipmaps of a texture come in they can fade in more detail.

Teufelhuhn

*prepares angry response*

*looks at tag*

Low blow. You win this round :x

In many games I played or watched that are 3D, most faraway objects tend to degrade quality or disappear from view. Why does this happen?

Gonzafan

In real life you're able to see more detail in objects that are closer to you than objects that are off in the distance.:|

things have to disappear eventually....this happens in real life too ya know...LMAO

console ram limitation I'd say since it don't really happen in pc games. imprezawrx500

What he's speaking about happens in EVERY pc game... Yes including the beloved Crysis.

[QUOTE="imprezawrx500"]console ram limitation I'd say since it don't really happen in pc games. bigblunt537

What he's speaking about happens in EVERY pc game... Yes including the beloved Crysis.

Lets now sit and discuss those unfortunate few who have no depth perception who will never be able to witness 3d TV...

[QUOTE="bigblunt537"]

[QUOTE="imprezawrx500"]console ram limitation I'd say since it don't really happen in pc games. imprezawrx500

What he's speaking about happens in EVERY pc game... Yes including the beloved Crysis.

Well you said it doesn't really happen in pc games I'm just pointing out it happens in every pc gaming. It's actually the number 1 graphical flaw that bothers me with gaming and I can't wait until it's a thing of the past.

As objects are farther away, the higher-quality models and textures are swapped for similar, low-quality ones. This allows developers to focus more power on things that are closer to you, instead of wasting it on things that are far.

Usually, LOD, as it's called, is done well, and you don't notice the swaps. When it's done poorly, it looks silly.