Measures, including a method, system, and computer program, for performing in-mission photogrammetry while an imaging platform is surveying a target environment. A plurality of images of the target environment are captured by the imaging platform. At the imaging platform, a representative subset of images is identified from the captured plurality of images. The imaging platform transmits the identified representative subset to a processing node. At the processing node, the transmitted representative subset is processed to generate a virtual model of the target environment.