Are Photogrammetry and 3D Scanning a real alternative to 3D modelling for Virtual Heritage applications?

Photogrammetry is promoted as a quick way to create realistic 3D models, while handheld 3D scanners are advertised for projects that require greater accuracy. Both technologies are increasingly being targeted for virtual Heritage applications. This paper presents the initial findings of a project that compares both methods for creating assets to be used in game engines to make interactive presentations. A range of test objects were chosen from small artefacts of about 10 cm up to ground features of about 8m in length. Hardware included the Faro Freestyle handset, while photographs were taken using a Nikon digital camera. An iPhone was also found to take adequate images and had an advantage in confined spaces. The time it takes to capture data was equivalent for both methods. More photographs and data points improve the accuracy of models. Bright sunshine was a problem for both methods: the 3D scanner was unable to pick up any data, while hard shadows in photographs produced artefacts in the resulting model. Processing software included Scene, Meshlab and ReCap. The scanner software was quicker to process but stitching together multiple scans can lead to inaccuracies. The polygon count of the resulting models is too high to use in UE4 so further manipulation was required using Maya and Z-Brush. The creation of Normal maps can help preserve detail, but the accuracy of textures is diminished. To modify the models to enable them to be used within interactive game engines still requires a high degree of 3D modelling expertise