In many civil engineering tasks, dimensional analysis of environmental objects is significant for spatial analysis and decision-making. Tasks such as as-built geometry generation need to efficiently interpret the critical dimensions of specific objects (e.g., diameter of a pipe, width of an opening) in a potentially cluttered environment based on data gathered from different positions. This paper presents a user-guided dimensional analysis approach to automatically acquire geometric information from a single frame of a depth sensor. Firstly a depth sensor is used to capture three-dimensional (3D) point clouds of indoor scenes. Then by extracting planes and performing geometric analysis, the dimensional information of objects of interest is obtained from a single frame. Our user guidance system evaluates the quality of the current data and measurement and provides interactive guidance for moving the sensor to acquire higher quality data, from which more accurate geometric measurements can be obtained. The proposed method has been tested on seven hallways and six door frames. The experimental results demonstrate that the method offers significant promise in enabling accurate dimensional analysis in a wide variety of civil engineering measurement contexts.