Trilinear (ideal for 3D configurators) is a straight extension of bilinear interpolation technique. It can be considered as linear interpolation of two bilinear interpolations (one for the front of the cell and one for the back). To calculate e and f we use two bilinear interpolations. To calculate g we interpolate linearly e and f along the z-axis (with tz, the z-coordinate of the sampling point g).
Trilinear interpolation has the same strengths and weaknesses as its 2D counterpart. It’s a fast and easy to implement algorithm, but it doesn’t give very smooth results. For volume rendering or fluid simulations where a very large number of lockups are performed in 3D grids, but it is still a very good choice.
Here is a simple example of trilinear interpolation on a grid. Note that, as with bilinear interpolation, the results can be calculated as a series of operations (rows xx to xx) or as the sum of the 8 corners of cells with some coefficients (rows xx to xx).
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