polygon count vs. triangle count?

Question

In a previous post I asked if 100,000 polygons is still the recommended size for USDZ Quick Look models on the web. (The answer is yes)

But I realize my polygons are 4-sided but are not planar, so they have to be broken down into 2 triangles when rendered.

Given that, should I shoot for 50,000 polygons (i.e., 100,000 triangles)?

Or does the 100,000 polygon statistic already assume polygons will be subdivided into triangles?

(The models are generated from digital terrain (GeoTIFF) data, not a 3D modeling tool)

1.8k

Posted by

Todd2

Reply

Triangles are used internally to construct polygons and your polygons shouldn't go past 4 sides and if they do then you should try to break into down into a smaller polygon.

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MobileTen

Answer 1

Yes, I would suggest you shoot for 100k triangles, but it's always worth testing if you can go over the suggested limit.

Posted by

Graphics and Games Engineer

Thanks.

I created a number of terrain maps of Mars this weekend with a grid of ~320 points on a side (= ~101K squares, 203K triangles). Everything seemed to work fine for a while, but after viewing several models for a while, the frame rate would drop. (It was a LiDAR-based device, which I'm guessing added a lot of its own mesh for occlusion purposes.)

I'll do the next batch of terrain models at at a resolution of 224 points on a side to see if that helps.

(Way back when I took computer graphics courses, we did everything in triangles. I guess I should keep that in mind.)

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Todd2
No problem, the frame rate drops are inevitable though, since iOS devices don’t have any active cooling, so eventually the device will have reduced clock speed caused by thermals. You could also try using the higher resolution model when the frame rate is high, and then switch to the lower resolution when the frame rate drops.

—
Graphics and Games Engineer

Answer 2

Yes, I would suggest you shoot for 100k triangles, but it's always worth testing if you can go over the suggested limit.

Posted by

Graphics and Games Engineer

Thanks.

I created a number of terrain maps of Mars this weekend with a grid of ~320 points on a side (= ~101K squares, 203K triangles). Everything seemed to work fine for a while, but after viewing several models for a while, the frame rate would drop. (It was a LiDAR-based device, which I'm guessing added a lot of its own mesh for occlusion purposes.)

I'll do the next batch of terrain models at at a resolution of 224 points on a side to see if that helps.

(Way back when I took computer graphics courses, we did everything in triangles. I guess I should keep that in mind.)

—
Todd2
No problem, the frame rate drops are inevitable though, since iOS devices don’t have any active cooling, so eventually the device will have reduced clock speed caused by thermals. You could also try using the higher resolution model when the frame rate is high, and then switch to the lower resolution when the frame rate drops.

—
Graphics and Games Engineer

Accepted Reply