His approach relied on the clear observation of architectural and natural forms. In works like his views of Kasteel Nijenrode and Weeresteyn Manor, he recorded the structural details of brickwork and fortifications. He used a fine line and controlled washes to define space. His compositions often feature wide horizons and receding waterways, such as the Vecht or the Amstel. Unlike the more atmospheric styles of his peers, Leupenius preferred a crisp, cartographic clarity. He documented the transition of the Dutch countryside into a managed, aristocratic environment.

Modern collectors value Leupenius for his unsentimental view of the past. His prints and drawings offer a literal window into seventeenth-century Holland. They represent a period when art and science were closely linked. These works suit contemporary interiors that favour clean lines and historical authenticity. His focus on specific locations, from the Huis De Omval to local inns like Het Molentje, provides a sense of place that remains relatable today. The work is a record of a specific moment in time, captured with the precision of a surveyor.