A dark, large soldier in a large hat seems almost too large as he faces the smiling, innocent girl, who is bathed in light and nervously holding the wine-glass in front of her. Contrast between the figures is established by scale, color, mood and attitude.
The figures are very close to the picture plane, like a wide-angle lens, emphasizing the differences in size and power between the figures. The vanishing point is midway between the two heads, emphasizing their bond. This picture may have been painted with a Camera Obscura, a newly invented optical device for projecting a scene onto a flat surface. (see the article by Philip Steadman for more details).
The map is by Balthasar van Berckenrode, from 1620. North is to the left, and the lake is visible which is now Amsterdam Airport. Cartography was becoming popular in mid-17th century Holland, and the expensive luxury of a map on the wall indicated education. The same map is also visible in The Love Letter.