Design of 3D and 4D Apps for Cultural Heritage Preservation

The design of three-dimensional and four-dimensional Apps, running on the main operating systems Android, iOS and Windows, is the next challenge in Digital Cultural Heritage (DCH) preservation. The enrichment of 3D virtual reality models, derived from computer graphics, computer vision, laser scanning, and aerial and close range photogrammetry by audio and video information acts as an excellent basis for App design. Based on experiences developing Apps for archaeology and architecture, the paper presents general workflows for data collection, storyboard design and App developments. The 4th dimension, time, can be injected into App content through the use of old photographs, sketches and paintings. The software package Unity is used as a cross-platform engine, offered by Unity Technologies, to create 3D/4D Apps for PCs, mobile devices and websites. One of the main results of the European Project "4D-CH-World" are two Apps of the Testbed Calw: the App "Calw VR" and the App "Tracing Hermann Hesse in Calw". Both Apps are using the 3D models created by interactive 3D modeling in Autodesk 3ds Max, with 3D data resulting from airborne LiDAR, terrestrial laser scanning, Structure-from-Motion (SfM) and Dense Image Matching (DIM). The geometric 2.5D reference surface is a LiDAR DSM, further improved by DIM results of georeferenced aerial photography with GSD@20cm.