Nebiker, Stephan
Lade...
E-Mail-Adresse
Geburtsdatum
Projekt
Organisationseinheiten
Berufsbeschreibung
Nachname
Nebiker
Vorname
Stephan
Name
Nebiker, Stephan
3 Ergebnisse
Suchergebnisse
Gerade angezeigt 1 - 3 von 3
- PublikationCloud-Based Geospatial 3D Image Spaces—A Powerful Urban Model for the Smart City(MDPI, 26.10.2015) Nebiker, Stephan; Cavegn, Stefan; Loesch, Benjamin [in: ISPRS International Journal of Geo-Information]In this paper, we introduce the concept and an implementation of geospatial 3D image spaces as new type of native urban models. 3D image spaces are based on collections of georeferenced RGB-D imagery. This imagery is typically acquired using multi-view stereo mobile mapping systems capturing dense sequences of street level imagery. Ideally, image depth information is derived using dense image matching. This delivers a very dense depth representation and ensures the spatial and temporal coherence of radiometric and depth data. This results in a high-definition WYSIWYG (“what you see is what you get”) urban model, which is intuitive to interpret and easy to interact with, and which provides powerful augmentation and 3D measuring capabilities. Furthermore, we present a scalable cloud-based framework for generating 3D image spaces of entire cities or states and a client architecture for their web-based exploitation. The model and the framework strongly support the smart city notion of efficiently connecting the urban environment and its processes with experts and citizens alike. In the paper we particularly investigate quality aspects of the urban model, namely the obtainable georeferencing accuracy and the quality of the depth map extraction. We show that our image-based georeferencing approach is capable of improving the original direct georeferencing accuracy by an order of magnitude and that the presented new multi-image matching approach is capable of providing high accuracies along with a significantly improved completeness of the depth maps.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationEvaluation of Matching Strategies for Image-Based Mobile Mapping(09/2015) Cavegn, Stefan; Haala, Norbert; Nebiker, Stephan; Rothermel, Mathias; Zwölfer, Thomas [in: ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences]The paper presents the implementation of a dense multi-view stereo matching pipeline for the evaluation of image sequences from a camera-based mobile mapping system. For this purpose the software system SURE is taken as a basis. Originally this system was developed to provide 3D point clouds or DEM from standard airborne and terrestrial image blocks. Since mobile mapping scenarios typically include stereo configurations with camera motion predominantly in viewing direction, processing steps like image rectification and structure computation of the existing processing pipeline had to be adapted. The presented investigations are based on imagery captured by the mobile mapping system of the Institute of Geomatics Engineering in the city center of Basel, Switzerland. For evaluation, reference point clouds from terrestrial laser scanning are used. Our first results already demonstrate a considerable increase in reliability and completeness of both depth maps and point clouds as result of the matching process.04 - Beitrag Sammelband oder Konferenzschrift
- PublikationVisualisation of Complex 3D City Models on Mobile Webbrowsers Using Cloud-Based Image Provisioning(Copernicus Publications, 2015) Christen, Martin; Nebiker, Stephan [in: ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences]Rendering large city models with high polygon count and a vast amount of textures at interactive frame rates is a rather difficult to impossible task as it highly depends on the client hardware, which is often insufficient, even if out-of-core rendering techniques and level of detail approaches are used. Rendering complex city models on mobile devices is even more challenging. An approach of rendering and caching very large city models in the cloud using ray-tracing based image provisioning is introduced. This allows rendering large scenes efficiently, including on mobile devices. With this approach, it is possible to render cities with nearly unlimited number of polygons and textures.01A - Beitrag in wissenschaftlicher Zeitschrift