Mesh Compression for 3D Graphics

IanDanforth writes "A new algorithm that uses successive approximations of detailed models to get significant compression has been revealed by researchers at The University of Southern California. Just as MP3s remove high frequencies we can't hear, this algorithm removes the extra triangles in flat or near flat surfaces that we can't see. Experts in the field are giving this work high praise and imply that is will be immediately applicable to 3D modeling in games, movies, CAD and more."

Comments

Proliferation of 3D Content on the Web?

[Alphanos]

Wide-spread use of graphics on the web didn't really take off until jpeg and gif compression became common. Will the easy compression of 3D models allow use of 3D content on the web to take off?

Re:Proliferation of 3D Content on the Web?

[Anonymous Coward]

Bandwidth probably isn't the problem, because 3D models can be described in ways that don't require much space. A renderman .rib file is far smaller than an image of the scene it describes, and a renderman shader can also be quite small. I'd expect something similar is the case for OpenGL.

I'd guess the bandwidth would really be taxed by the transmission of bitmaps used for textures. That won't be helped by removing triangles from the model.

I expect any acceleration would be in the processing on your computer. The CPU and/or GPU would have less work to do, because of the reduced number of triangles to render. So your game gets a higher frame rate, and/or uses fewer cycles, or can perform faster with less powerful hardware.

The real reason 3D content hasn't taken off is that it frankly isn't very useful for every-day browsing.

Patented?

[CharAznable]

So, is this something everyone can use, or will it be patented?

MP3 compression == complicated

[Raindance]

I think this is interesting, but the analogy drawn between MP3s and this 3d-object compression is a bit strained.

The MP3 compression routine revolves around 'frequency masking' much more than it does "remov[ing] high frequencies we can't hear". Most of the work in MP3 is done through 'frequency masking'. That is, imagine a graph of the frequencies being played at any given time- find the high points, then draw sloping lines down to either side of those points. Humans can't hear anything under those lines- they're 'masked' by the nearby strong frequency.

Nothing very much like that goes on in this algorithm. There might be some other mesh-compression-analogous process that goes on in MP3 that's like this, but that ain't it.

Sorry to nitpick, but I figured it's important that
1. MP3 compression is not just simply throwing out high frequencies (a lot of these are actually retained) and
2. This isn't anything analogous to that, anyway.

Looking over my post, I'd have been fine if the submitter had said "Just as MP3s remove frequencies we can't hear, this algorithm removes..." but that's not very descriptive anyway.

RD

CAD??? ;-)

[PaulBu]

Well, if THAT surface was there I bet there was someone to put it there, and (s)he thought that it had some useful function...

How would you like to fly a plane designed without those thin "thingies" called "wings"? ;-)

Paul B.

This has been around for many years.

[Speare]

Man, this has been around for years. I'd bet a decade. Almost all GPSes with mapping features use a 2D variant of this to store less line segment data for roads. 3D systems with multiple levels of detail choose among a number of differently-optimized models to reduce vertex transformation overhead on far-away objects. Where have you guys been?

Re:This has been around for many years.

[MrBigInThePants]

You both should try reading the article:

Computer scientists have struggled with the problem of finding an optimal mix of large and small elements for years. In 1998, theoreticians proved that the problem was "NP hard" that no general solution exists that can be solved by a computer in finite length of time. They did find work-arounds: fast methods to simplify meshes, which were unable to guarantee accuracy, and accurate techniques, which were too slow.

The Desbrun teams novel approach comes from the seemingly unrelated field of machine learning using a technique invented in 1959 called Lloyd Clustering named after its inventor Stuart Lloyd. Desbruns algorithm uses it to automatically segment an object into a group of non-overlapping connected regions an instant draft alternative to the too-numerous triangles of the original scan.

If you actually read it, it would be pretty obvious why this is new...sheesh!

Also, game data is built of far fewer triangles and in a much easier form than raw data read from a real-life source. (such as a laser range finder)LOD mesh reduction is usually done by full or partial MANUAL selection.

Re:This has been around for many years.

[Jerry Talton]

In 1998, theoreticians proved that the problem was "NP hard" that no general solution exists that can be solved by a computer in finite length of time.

Wow. That's pretty far from what "NP hard" actually means.

Re:Greatness!

[42forty-two42]

I am for cannot waiting able frequency to this have! I too am so greatness compression going to get.

Slashdot's using lossy compression on posts now?

No.

[autopr0n]

This isn't about compressing the data required to store a mesh, although it will help.

This is about reducing the complexity of meshes so that they can render faster.

This isn't new?

[grammar fascist]

Un-disclaimer: I'm currently pursuing a PhD in machine learning.

Yes, it is new. First of all, y'all need to read the article and find out how.

It is for two reasons, both of which are stated:

The Desbrun team's novel approach comes from the seemingly unrelated field of machine learning...

Machine learning: getting a computer to generalize (invent hypotheses) given data instances. Work in machine learning has proven that generalization and compression are equivalent. That someone has applied those ideas to 3D model compression is at least notable.

We believe this approach to geometry approximation offers both solid foundations and unprecedented results...

In other words, it's not using some hacked-up heuristics. The bias behind the generalizations it makes are solidly described, and can be tuned. Machine learning consistently beats heuristics in accuracy, so their expectation of "unprecedented results" has a good foundation.

I'd say multilevel meshes is a better answer...

[CompSci101]

The immediate problem that springs to mind for me is that current graphics cards and APIs don't produce good shading effects when the geometry is turned down. Gouraud shading (color-per-vertex interpolated across the face of the triangle) is the best that hardware acceleration will handle right now, and turning down the number of vertices will lead to problems with detailed color operations under normal circumstances (complicated lighting/shadow effects, etc.)

Shouldn't the industry be pushing further toward graphics cards that can accelerate true Phong shading, rather than shortcuts and texture mapping tricks? Or even automatic interpolation between meshes of different complexity depending on how much of the scene a particular model takes up? If that functionality was developed first, then this mesh optimization would make perfect sense. But, for now, anyway, it seems like getting rid of the geometry is going to force developers to continue to rely on tricks to get the best look out of their engines.

Not that you'd HAVE to use it, though...

C

Re:Excellent!

[dasmegabyte]

No, what it will usher in is a new wave of whining when companies go with some proprietary method of mesh compression instead of whatever compression is eventually developed by the Ogg team.