Dürer, who for decades made use of the same draughtsmanly ‘toolbox’ for constructions, was also apparently able to develop his schemata dynamically. Unusually, in the Vienna Portrait of a Young Venetian Woman, which in no way resembles the other Venetian lady held in Berlin, the grid of nine fields is tilted.[1] 

The lines running upwards to the left corner are arranged parallel to one side of a triangle that touches the cheek of the unknown sitter. A further side of the triangle lies exactly on the chin line of the linear grid, whereas the upper line runs precisely through a point of intersection along the hairline.

In this painting it can be presumed that first the straight line along the cheek and the complete triangle were conceived from edge to edge of the image before Dürer laid out the grid to structure the face and upper head.

As a rule, the first step has to be the production of a central vertical along which the Vitruvian tripartite division is then carried out. (This creates six fields, to which three more have to be added on the right-hand side in the case of a three-quarter profile.)

Frequently there are indications of where this central vertical begins and ends or through which points it runs. But in the case of the Venetian woman in Vienna there is only one discernible place: the corner of the eye at the bridge of the nose. The line along the cheek, however, targets exactly a point along the edge of the image that marks the white ribbon on the reddish dress.