Using Dynamic Pulse Function for Semantic 3D Modeling of Historical Landmarks

Abstract

The pulse function (PF) is a technique based on procedural preprocessing system to generate a computerized virtual photo of the façade with in a fixed square size. Dynamic Pulse Function (DPF) is an enhanced version of PF which can create the final photo, proportional to real geometry. This can avoid distortion while projecting the computerized photo on the generated 3D model. The challenging issue that might be handled for having 3D model in LoD3 rather than LOD2, is the final aim that have been achieved in this paper. In this research the parameters of Dynamic Pulse Functions are utilized via Ruby programming language in SketchUp Trimble to generate (exact position and deepness) the windows and doors automatically in LoD3 based on the same concept of DPF. The advantage of this technique is automatic generation of huge number of similar geometries e.g. windows by utilizing parameters of DPF along with defining entities and window layers. In case of converting the SKP file to CityGML via FME software or CityGML plugins the 3D model contains the semantic database about the entities and window layers which can connect the CityGML to MySQL. The concept behind DPF, is to use logical operations to project the texture on the background image which is dynamically proportional to real geometry. The process of projection is based on two vertical and horizontal dynamic pulses starting from upper-left corner of the background wall in down and right directions respectively based on image coordinate system. The logical one/zero on the intersections of two vertical and horizontal dynamic pulses projects/does not project the texture on the background image. It is possible to define priority for each layer. For instance the priority of the door layer can be higher than window layer which means that window texture cannot be projected on the door layer. Orthogonal and rectified perpendicular symmetric photos of the 3D objects that are proportional to the real façade geometry must be utilized for the generation of the output frame for DPF. The DPF produces very high quality and small data size of output image files in quite smaller dimension compare with the photorealistic texturing method. The disadvantage of DPF is its preprocessing method to generate output image file rather than online processing to generate the texture within the 3D environment such as CityGML. Furthermore the result of DPF can be utilized for 3D model in LOD2 rather than LOD3. In the current work the random textures of the window layers are created based on parameters of DPF within Ruby console of SketchUp Trimble to generate the deeper geometries of the windows and their exact position on the façade automatically along with random textures to increase Level of Realism (LoR). As the output frame in DPF is proportional to real geometry (height and width of the façade) it is possible to query the XML database and convert them to units such as meter automatically. In this technique, the perpendicular terrestrial photo from the façade is rectified by employing pr...

3D Real Scene Data Collection of Cultural Relics and Historical Sites Based on Digital Image Processing

“…In 3D scanning, the surface data of the obtained 3D object inevitably contains noise due to equipment factors and the properties of the scanned object. This mainly consists of outliers, including outlier point groups (nonconnected terms) and outlier scattered points (outside outliers) [ 17 ]. Therefore, after the 3D scanning point is acquired, noise reduction should be performed first.…”