Historically, government organizations have developed "operations centers" as hubs for command and control functions. Over the past decade there has been significant interest in shared situational awareness and collaboration as well as improvement in networking capabilities of these organizations, which has resulted in concepts and terms such as Common Operational Picture, Common Relevant Operational Picture, and User-Defined Operational Picture. These 'pictures' make operational information available directly to an individual's desktop (outside the operations centers). This paper defines and introduces the technology concepts for a User-Defined Operational Picture (UDOP) that enable collaboration by providing visual situational awareness to end-users working within an operational Network-Centric environment that is offering an increasing number of web service-enabled information sources. UDOPs are created, visualized, augmented, tailored, and shared by the organization to enhance situational awareness and support collaborative and hierarchical decision-making.The UDOP architecture supports 2D, 3D, and 4D (3D + time) visualization using COTS technologies. Implementation of a robust and flexible UDOP system relies on several key system design patterns that include Service Oriented Architecture (SOA), plug-in mechanisms, layer/filter models, and loose coupling. This paper will also describe one reference implementation of a UDOP system by reviewing an operationally deployed capability called Global Awareness Presentation Services (GAPS).