Bug(s): 1: Bad pixel in clips using Tiny Planet. 2: Severe aliasing...

NightHawkInLight wrote on 11/18/2019, 10:01 AM

Version: 17.0.0.353

Bug 1: I have found working with 360 video that there is a single bad pixel dead center in any clips where the Tiny Planet plugin is applied. This pixel becomes predictably larger the more the video is downscaled upon rendering.

Bug 2: Aliasing occurs upon rendering that increases in severity proportional to how much the footage has been downscaled.

Note: I am aware of the already known bug:

[VP14+] Anti-aliasing of downscaled media is insufficiently smooth when its alpha channel information is set to Straight (unmatted), Premultiplied, or Premultiplied (dirty) and GPU acceleration is OFF.

In my case, the issue of severe aliasing occurs despite GPU acceleration being enabled, and the alpha channel on affected media is set to 'none'. Footage in attached frame was downscaled from 5.7k to 1920x1080.

Comments

VEGASPascal wrote on 11/18/2019, 10:39 AM

I will write you a PM.Both bugs sounds funny.

VEGASPascal wrote on 11/20/2019, 3:52 AM

@NightHawkInLight gave me the project file and the original file. It's not a bug, it's a combination of features that cause this bug. Here are some hints that sometimes lead to errors.

  • always use the original resolution for 360° videos as project resolution... otherwise: black holes at top and bottom, blur artefacts, stitching error (ghosting)
  • Tiny Planet: is a transformation (stereographic projection) and a cut out... like a transformation from 360° space (equirectangular) to the "normal camera" space... or like the projection of a sphere to a plane. You see the effect in the 360° mode of the preview. So keep in mind that after you use the "Tiny Planet" effect you leave the 360° domain (and all plugins after this will not see the whole frame).
  • Scene Rotation: is a shift of the center view in the 360° domain. The video always stays in the 360 ° domain, but now you can move the center from front to back or to any point in the video. This plugin is useful to put that to the center of attention (VR or Youtube 360 ° Player).

The dead spot and the blur is a combination of all 3.

VEGASPascal wrote on 11/20/2019, 4:11 AM

@NightHawkInLight Your input is 5760x2880 (aspect ratio: 2:1) and your output is 1920x1080 (aspect ratio: 16:9). What happens in the rendering? In your plugin chain is "pan/crop" the first plugin which is downscaling the frame to 1920x1080... your 360° frame. Next, you use "Tiny planet" which is doing a cut out of a low resolution (the result is blurred and with wrong pixel format).

1 solution: Add "Tiny Planet" before "Pan/Crop" in your plugin chain... but you are losing the animation in "Tiny planet".

2 solution: Rendering twice. First "Tiny Planet" with animation in the same resolution and than do the rendering in a lower resolution.

Maybe somebody else could give you a better solution.

NightHawkInLight wrote on 11/20/2019, 7:44 AM

Thank you very much for your work in helping to figure this out. I want to address your first point though:

always use the original resolution for 360° videos as project resolution... otherwise: black holes at top and bottom, blur artefacts, stitching error (ghosting)

I've found I can correct this simply by unlocking 'maintain aspect ratio' and the 2:1 footage stretches to fill the 16:9 space (the project file I sent you should have been saved at 5120 x 2880, 16:9 5k resolution). That's the only solution I have found to being able to work with 360 footage and mix it with other 16:9 media on the same timeline without black bars (or black holes). The solution of moving the Tiny Planet plugin to preceded Pan/Crop causes stitching issues in combination with the stretched aspect, but it works fine if placed after (apart from the center pixel/aliasing). You can see in this clip that I have been able to avoid black holes even at a 16:9 output:

That is a 4k render so the center pixel error and amount of aliasing is small, but still present. These errors disappear if I remove Tiny Planet and just rely on Scene Rotation and Track Motion to crop in, but then look how nauseating the motion becomes in comparison:

So that is why I started applying Tiny Planet at all. It makes the 360 footage look much more natural even when projected flat. If these are errors that can't be corrected I suppose I'll just have to render out at 4k and live with a white dot and a little more saw teeth than I'd like. I'll have to see if I can cover the center pixel with a mask of an adjacent one.

In your plugin chain is "pan/crop" the first plugin which is downscaling the frame to 1920x1080...

That was very interesting to learn...So Pan/Crop is the part of the chain where any(?) type of scaling takes place upon rendering? I did not know that and it may come in handy in figuring these issues out. that makes a lot of sense as to the cause of the aliasing issue. Thank you!