2.5D

In machining, 2.5D refers to a surface which is a projection of a plane into 3rd dimension - although the object is 3-dimensional, there are no overhanging elements possible. Objects of this type are often represented as a contour map that gives the height (i.e., thickness or depth) of the object at each point.^[1]

2.5D objects are often greatly preferred for machining, as it is easy to generate g-code for them in an efficient, often close to optimal fashion, while optimal cutting tool paths for true 3-dimensional objects can be NP-complete, although many algorithms exist.

2.5D objects can be machined on a 3-axis milling machine, and do not require any of the features of a higher-axis machine to produce.

A 2.5D machine possesses the capability to translate in all three axes but can perform the cutting operation only in two of the three axes at a time. The code for a 2.5D machining is significantly less than a 3D machining.

A 2.5D image is a simplified three-dimensional (x, y, z) surface representation that contains at most one depth (z) value for every point in the (x, y) plane

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