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Old 24th July 2007, 01:35 PM   #1
Wiggles
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Default Professional polycount.

I noticed some very professional looking models have very high poly count.

I was messing around to see how many poly's my computer can handle.

I created a torus by drawing and ellipse with 360 points, then revolved it with 360 segments. It makes for 129600 poly

It took at least a minute for it to revolve, I'm not sure I had to walk away for a bit.

It seems a tad more catchy when in inspect mode, and quite a bit more catchy when moving it around not in inspect mode.

Afraid of even trying to render it.

I'm guessing with my current setup I couldn't draw a professional high poly model.

It makes for one pretty smooth donut though
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Old 24th July 2007, 02:34 PM   #2
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Default Re: Professional polycount.

I just confused myself even more, lol.

I decided to go ahead and render it, to see how long it takes, and to my suprise it didn't take long at all.

I just exported to Povray, and did a quick render.
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Old 24th July 2007, 02:50 PM   #3
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Default Re: Professional polycount.

There are also some very professional looking low-polys models, but I see your point
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Old 24th July 2007, 03:42 PM   #4
lisa
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Default Re: Professional polycount.

Don't sweat it. You might not be able to push as many polys as the "pros", but even the pros use A LOT of tricks to do what they do... they don't push as many polys as you'd think, because they have to keep the render times in check.

Some common tricks: Surface shading often makes a bigger difference than poly-count allow. Try playing with crease angle, and you'll see. Another trick along those lines is normal mapping. This is especially useful for high-detail surfaces, for things like pores or wrinkles on a character's skin, although games use it even for larger details.

Also, most films are rendered in multiple passes, both because of memory and render time... even they can't have that much stuff all in one shot either; so they render different parts using the best tools for the job, then comp it. A film studio may build dozens of different versions of the same object at different levels of detail, known as LOD. When the object is distant, they'll use the low LOD, and switch to a higher one only when the object is close. Often, the close-up model is just a partial--it only includes just the items visible in the shot--to keep the memory footprint manageble.

Sometimes, objects that don't change in the frame aren't rendered on each frame: a single billboard is rendered, then the billboard is used in the shot to cut times on subsequent frames. The billboard only gets re-rendered when the camera has moved enough that the angle has changed. This is known as an "imposter" object.

As well, some objects benefit from raytracing, but others don't, so it's also very common to render different objects with different quality settings and composite them. What you see in the final frame of a Hollywood movie is almost never rendered all at the same time.

You can use all of these same tricks on a smaller scale to make your scenes look very professional, even on a small budget.
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Old 30th July 2007, 09:11 PM   #5
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Default Re: Professional polycount.

Quote:
Originally Posted by lisa View Post
Don't sweat it. You might not be able to push as many polys as the "pros", but even the pros use A LOT of tricks to do what they do... they don't push as many polys as you'd think, because they have to keep the render times in check.

Some common tricks: Surface shading often makes a bigger difference than poly-count allow. Try playing with crease angle, and you'll see. Another trick along those lines is normal mapping. This is especially useful for high-detail surfaces, for things like pores or wrinkles on a character's skin, although games use it even for larger details.
Any links to info on these particular subjects? Game makers are masters of these tricks. They must be, because they put out some unbelievable visuals that still perform in real-time. I'd like to learn as much as possible on this.
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Old 1st August 2007, 07:06 PM   #6
lisa
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Default Re: Professional polycount.

Sure thing!

Here is a very good tutorial on normal mapping, with lots of pictures plus a simple shader implementation. This should give you a clear, visual example of how altering the surface normals changes the perception of the shape--without changing the geometry:
http://www.bencloward.com/tutorials_normal_maps6.shtml

Tip: If you want to use AC3D to make normal maps from high-resolution models and you use POVRay as your default renderer, you'll want to download MegaPOV and use it instead. MegaPOV will let you render normals as a pigment, but the "official" POVRay build won't (yet).

These links are a bit old, but they are a very straight-forward explanation of imposter rendering. The first link has a video so you can see it in action:
http://www.markmark.net/clouds/
http://www.gamasutra.com/features/20...davis_01.shtml

Good video tutorial explaining LOD. This is Maya-specific, but the concepts are the same regardless of which renderer you are using:
http://www.digitaltutors.com/digital...ails.php?v=895

The type of LOD shown in the tutorial is called "discrete LOD". There are other types, such as CLOD and progressive meshes, but DLOD is most commonly used--especially in games--because it is easy to implement and *much* less computationally expensive than other methods. DLOD usually causes a small amount of "popping" as you switch between meshes, which is why other methods exist, but if you tune your scene right the popping is usually not noticable.

If you have questions on the specifics of any of these, ask away. I've had my hands under the hood of quite a few game engines over the years, so I've implemented all of these at one point or another.
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