Stefan Röttger MedicalVisualization/3D Texturinterpolation (Trilinear)

3D Texturinterpolation (Trilinear)

← Trilinear Interpolation | ● | Data Representation →

The data value at normalized texture coordinates $(s,t,r)\in[0,1]$ is determined via Tri-linearer Interpolation of 8 corner values $P_{000}...P_{111}$ :

$P_{000}=V(i,j,k)$

$P_{100}=V(i+1,j,k)$

$P_{010}=V(i,j+1,k)$

$P_{110}=V(i+1,j+1,k)$

$P_{001}=V(i,j,k+1)$

$P_{101}=V(i+1,j,k+1)$

$P_{011}=V(i,j+1,k+1)$

$P_{111}=V(i+1,j+1,k+1)$

at the index (of the left front bottom corner of the bounding voxel)

$i=\lfloor s\cdot(w-1)\rfloor$

$j=\lfloor t\cdot(h-1)\rfloor$

$k=\lfloor r\cdot(d-1)\rfloor$

Then the three linear interpolation weights $u,v,w\in[0,1]$ are:

$u = s\cdot(w-1) - \lfloor s\cdot(w-1)\rfloor$

$v = t\cdot(h-1) - \lfloor t\cdot(h-1)\rfloor$

$w = r\cdot(d-1) - \lfloor r\cdot(d-1)\rfloor$

The tri-linear interpolation equals three subsequent linear interpolations along the x-axis (red), the y-axis (green) and the z-axis (blue). The resulting interpolated function value is depicted in yellow.

The function value is therefore:

$\displaystyle{ f(u,v,w) = }$

$\displaystyle{ (1-w)((1-v)((1-u)P_{000}+uP_{100}) + }$

$\displaystyle{ v((1-u)P_{010}+uP_{110})) + }$

$\displaystyle{ w((1-v)((1-u)P_{001}+uP_{101}) + }$

$\displaystyle{ v((1-u)P_{011}+uP_{111})) }$

The trilinear interpolation requires ca. 30 Flops (per rasterized fragment).

← Trilinear Interpolation | ● | Data Representation →

Stefan Röttger

3D Texturinterpolation (Trilinear)

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