Since TrueType fonts can handle either approach, the choice depends upon the preference of the font manufacturer. In such a case, the drawing must be converted into digital data. The problem of digitizing a paper design can be solved in either of two ways. The art work can be scanned and the scanned image used as a template. Alternatively, a hand-held digitizing device can be moved over the art work with critical points describing the glyph's shape recorded.
Critical points are corner and tangent points.
Curve points that fall at extrema are also important. Hand digitization has the advantage that it allows the person doing the work to smooth out any roughness in original image. When digitizing art work, the size of the drawing is important since it will be the key factor in determining the accuracy of the final result. Increasing the size will give finer control of detail. As a rule of thumb you should digitize art at an accuracy that is two times that you wish to achieve in the final result.