Scanning of objects to produce 3D models is becoming more commonplace as the required hardware is becoming less expensive and more widely attainable. The process involves obtaining scans of multiple views so as to create a complete 3D model. This is typically a user-driven process, and an analysis of the difficulty of this task, use of automation, visualization methods, and their effect on the final result has not yet been thoroughly investigated. In this paper we report on a user study related to 3D scanning in which the user is asked to use a simulated, somewhat simplified 3D scanner with a simple user interface. Our investigation focuses on scanning the complete surface of an object with decent sampling density, but does not take all sampling issues, such as reflections, into account. We evaluate different visualization methods, which aim to help the user complete or improve scans, and compare the results obtained by participants to those obtained using an automated approach. The results show that users can easily obtain complete scans or improve existing scans using this simple interface, and that different visualization methods are more or less equally effective; moreover, user performance is on par with automated scanning methods.