Sharp Ridge Structures in Flow Visualization

• Applicant: Professor Dr.-Ing. Holger Theisel
• Subject Area: Image and Language Processing, Computer Graphics and Visualisation, Human Computer Interaction, Ubiquitous and Wearable Computing ; Software Engineering and Programming Languages
• Term: from 2013 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 224905231

Ridges are well-studied structures with a variety of applications in image and shape analysis as well as in scientific visualization. There are many different definitions for ridges, each of them having its advantages and disadvantages. In fact, there is an active research on numerical extraction algorithms for each of the ridge concepts. In flow visualization, a number of modern analysis techniques are integration-based, i.e., new fields are created by advecting and integrating information over certain finite integration times. There are fundamental differences to ridges that usually occur in visualization or image processing: they tend to be extremely sharp, making conventional ridge extractors not applicable for larger integration times. The project attempts to give a formal analysis of the sharpness of integration-based ridges, showing that standard ridge extractors have a limited applicability even under consideration of adaptive mesh refinement. To overcome this, a new approach for the extraction of sharp ridges is proposed, which is based on a tracking of previously non-sharp ridges. For sharp ridges, simplified extraction algorithms as well as new volume rendering approaches will be introduced. Sharp ridge extractors are applied to extract ridges in FTLE, FSLE, streak line and time line fields as well as for extracting shock waves.

• DFG Programme: Research Grants