Here's a question - why do 3D models on the PS1 tend to shake and jitter like they do?

General information to do with the PlayStation 1 Hardware. Including modchips, pinouts, rare or obscure development equipment, etc.
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ShawHale
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Here's a question - why do 3D models on the PS1 tend to shake and jitter like they do?

Post by ShawHale » April 25th, 2021, 4:24 am

You know what I'm talking about. There was a game, I think Time Crisis, that had an island in its opening scene. We used to call it Earthquake Island because of how dramatically is pulsated on the screen. Why is this?

I recently started playing PS1 games on an emulator, and even if you turn up the resolution so that the models look completely clear, they'll still shake around, changing shape with every movement. It's not as odd looking at the default resolution, so I keep it there.

What's the technological reasons behind this? The N64 didn't have this problem.

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Post by Jidori-Ya » April 25th, 2021, 7:54 am

The game use a native resolution of 256x240, so it looks a bit crappy on PS1.
I played the Arcade version and obviously had no problems whatsoever, besides having better graphics.
I believe that to adapt it to the PS1 version, the compromises were many.
It could be some kind of problematic VSync.
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Post by Elbart » April 26th, 2021, 2:03 am

ShawHale wrote: April 25th, 2021, 4:24 am I recently started playing PS1 games on an emulator, and even if you turn up the resolution so that the models look completely clear, they'll still shake around, changing shape with every movement. It's not as odd looking at the default resolution, so I keep it there.
There's more than one graphical artifact the PS1 rendered. There are two main ones:

-Texture Warping. PS1 lacked a lot of texturing ability such as perspective correction. Easily seen when looking at a "straight" line on a texture that wasn't straight. Floors are the perfect place to see this. Driving games suffer a lot from this.

-Polygon Jitter. PS1 didn't have subpixel rasterization, which means the vertices were "snapped" to the pixel grid. The Nintendo DS suffers the same problem and has the exact same artifact. Easily seen in a static scene with a mesh that is "breathing" or animating slowly. Check out the NDS remakes of FF3 and FF4 during cutscenes.

PS1 didn't have a Z-buffer, but it wasn't the primary cause of the two above artifacts. Crash Bandicoot 2 and 3 implemented software Z-buffers in special areas, but the games still suffers from the two above issues.
https://www.neogaf.com/threads/why-do-p ... -126335939

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Post by Shadow » May 26th, 2021, 2:48 pm

The PSX doesn't have a floating point co-processor so everything is integer based for high-speed computational output. Technically you can do FPU operations but it's all software emulated which is slow. Overall, because of the lack of an FPU it results in quick movements which aren't fluid.
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