How are print dimensions calculated in UV Tools (not sure if this should be a bug report)

[cunabula27]

I have this layer which is 280px square and on my printer a pixel is 28.5um. UV Tools recognises both of these and says the layer should come out at 8.12mm square but 280 x .0285 is 7.98 not 8.12.

Is there something I'm missing that makes this difference make sense?

Or do you think this is a bug?

Edit: I've just done the obvious reverse calculation and it appears to be a rounding issue. I think UV Tools is using 0.029 for the pixel calculation.

[sn4k3]

Most likely is a rounding, calculation can be found here:

UVtools/UVtools.Core/FileFormats/FileFormat.cs

Lines 1751 to 1764 in df7d434

	/// <summary>
	/// Gets the pixel width in millimeters
	/// </summary>
	public float PixelWidth => DisplayWidth > 0 && ResolutionX > 0 ? (float) Math.Round(DisplayWidth / ResolutionX, 3) : 0;
	/// <summary>
	/// Gets the pixel height in millimeters
	/// </summary>
	public float PixelHeight => DisplayHeight > 0 && ResolutionY > 0 ? (float) Math.Round(DisplayHeight / ResolutionY, 3) : 0;
	/// <summary>
	/// Gets the pixel size in millimeters
	/// </summary>
	public SizeF PixelSize => new(PixelWidth, PixelHeight);

UVtools/UVtools.Core/Layers/Layer.cs

Lines 214 to 225 in df7d434

	public RectangleF BoundingRectangleMillimeters
	{
	get
	{
	var pixelSize = SlicerFile.PixelSize;
	return new RectangleF(
	(float) Math.Round(_boundingRectangle.X * pixelSize.Width, 2),
	(float)Math.Round(_boundingRectangle.Y * pixelSize.Height, 2),
	(float)Math.Round(_boundingRectangle.Width * pixelSize.Width, 2),
	(float)Math.Round(_boundingRectangle.Height * pixelSize.Height, 2));
	}
	}

To have better precision I can increase the rounding to 4 on the PixelSize

[cunabula27]

Thank you for the quick reply. I was working on calibrating my printer and that was making me scratch my head a bit.