| CPC G06F 30/17 (2020.01) [B33Y 50/00 (2014.12); B33Y 80/00 (2014.12)] | 23 Claims |

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1. A computer-implemented method for calculating a digital twin of a spectacle lens for a purpose of a use of the digital twin for a manufacture of the spectacle lens, the digital twin comprising a layer stack, wherein one of a following conditions for a dithering placement of a volume element applies:
when in 50% or in less than 50% of discrete xm,ym,zm . . . xn,yn,zn positions of an adjacent layer of the layer stack the volume element is positioned, then no volume element is positioned in discrete xm+1,ym+1,zm+1 . . . xn+1,yn+1,zn+1 positions of a layer of the layer stack, a discrete xm+1,ym+1,zm+1 . . . xn+1,yn+1,zn+1 position of the layer being directly adjacent and on top of a respective discrete xm,ym,zm . . . xn,yn,zn position of the adjacent layer;
when in more than 50% of discrete xm,ym,zm . . . xn, yn,zn positions of an adjacent layer of the layer stack a volume element is positioned, then volume elements are positioned in at least one of:
discrete xm+1a . . . z,ym+1a . . . z,zm+1a . . . z . . . xn+1a . . . z,yn+1a . . . z,zn+1a . . . z positions of a layer of the layer stack, a discrete xm+1a . . . z,ym+1a . . . z,zm+1a . . . z . . . xn+1a . . . z,yn+1a . . . z,zn+1a . . . z position of the layer not being directly adjacent and not being on top of a respective discrete xm,ym,zm . . . xn,yn,zn position of the adjacent layer, or
discrete xm+1,ym+1,zm+1 . . . xn+1,yn+1,zn+1 positions of a layer of the layer stack, a discrete xm+1,ym+1,zm+1 . . . xn+1,yn+1,zn+1 position of the layer being directly adjacent and on top of a respective discrete xm, ym,zm . . . xn,yn,zn position of the adjacent layer,
wherein the dithering placement minimizes a formation of a residual structure in the layer stack, and
wherein the dithering placement results in a variation of a volume element density based on the conditions for the dithering placement of the volume element, the variation of the volume element density in the layer of the layer stack being a digital representation of a variation of ink droplets in the layer.
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