Instructors often have to deal with the fact that available synthetic environments do not match their specific training requirements. Geo-specific terrains are not guaranteed to provide the desired setting. Dedicated geo-typical terrain databases can help solve this issue because they can be modeled explicitly to match training requirements. However, existing editing environments for this type of terrains are often laborious and expensive in use. Procedural modeling techniques may help in rapidly building geo-typical terrains, but tools that support these techniques are difficult to configure and do not allow for direct integration of the instructor’s intentions into the modeling process. In this paper, we present the results of a PhD study into the use of a novel declarative method for modeling synthetic environments. This method proposes a workflow that exploits procedural techniques to rapidly generate terrains, controlled by intuitive declaration of the terrain from an instructor’s perspective. At the basis of the method is a concept of interactive sketching of terrain features and constraints at a higher level of abstraction, close to the instructor's intents, while maintaining a short feedback loop on the resulting terrain. We have evaluated the use of this approach for a variety of training simulators currently in use within the Dutch DOD. Our observations show that the approach provides an effective instructor-centered alternative to current methods. Challenges exist in creating varied content, as well as in providing appropriate methods to express user intent in terms of terrain features and constraints, while ensuring consistency in the resulting model. We describe our solutions to these challenges and discuss the value of our method for the military training simulation community.