Teacher

prof. Domenico VISINTINI

Credits

6 CFU

Objectives

The course aims to understand the potential of modern 3D surveying of building structures done by photogrammetric and laser scanning techniques. First of all the analytical-geometrical aspects allowing "3D measurement from photographs 2D" are treated and then the equipment used for the acquisition and the elaboration of so acquired images are shown. After that, the main techniques of digital image processing and related software that automate many process steps are analysed. The advanced laser scanning and photogrammetric integrated technology, i.e. the optimum for 3D modeling of buildings, is later explained and applied in practice, Summarizing, the course explores the geomatics techniques and the practical operations making possible the creation of the solid model of an existing construction.

Acquired skills

- Knowledge of the most modern techniques of 3D surveying detection and modeling of the "status" of building works, often built with irregular and complex geometries.
- Understanding of the specific potential, operating limits / costs and integrability of the methods and the software for photogrammetric / laser scanning surveying and 3D modeling.
- Ability to build a 3D solid model of a construction, inserted and integrated with the available cartographic representations and/or advanced representations of virtual reality

Contents

Introduction: basic concepts, aims and methods of the (terrestrial) architectural surveying techniques, geometrical survey (surveying) and structural analysis according to the rules, examples. (3 hours)

Topographic surveying - recalls: detail and referencing measures, polygonal and topographic networks, processing of statistical adjustment of topographic measurements, examples. (2 hours)

Photogrammetric surveying - techniques: collinearity equations, images external orientation, object-points 3D restitution, stereoscopic 3D models, relative and absolute orientation of a 3D model, aerial triangulation, 2D rectification, "2,5D" ortho-projection, examples. (10 hours)

Photogrammetric surveying - instruments: objectives distortion and calibration, systems for photogrammetric acquisition and restitution, characteristics of modern digital systems, examples. (2 hours)

Photogrammetric surveying - automation: RGB, CMY and HSL space color, process of pre-processing, treatment, restoration, enhancement of digital images, examples, edge detection, raster to vector conversion, recognition of homologous points, examples, fully automatic photo-modeling (from Computer Vision), examples. (6 hours)

Laser scanning surveying - instruments: distance and triangulation systems for acquire 3D point clouds, examples. (2 hours)

Laser scanning surveying - techniques: steps of acquisition, registration, geo-referencing, 3D modeling, and texturing with digital images, examples. (5 hours)

Integration among surveying techniques: characteristics of the architectural surveying, technical specifications for 1:50 scale numerical surveying, 3D solid modeling with SketchUp from various surveying techniques, examples. (3 hours)

Aerial surveying of the buildings - instruments: photogrammetric and laser scanning aerial systems, examples. (2 hours)

Aerial surveying of the buildings - techniques: production methods of technical numerical mapping, I, II, III and IV class cartographic products, comparative examples, direct orientation of surveying sensors, 3D models of buildings and cities in virtual reality environments and in Google Earth. (4 hours)

Exercises in situ and in laboratory: topographic, photogrammetric and laser scanning surveying and 3D modeling of a building/structure - with practical application, by using various software, of most of the theoretical topics seen during the course. (21 hours)

References

- Visintini Domenico, PROIEZIONI POWERPOINT DELLE LEZIONI (in Italian), 2016 (available at site http://materialedidattico.uniud.it/)
- Bezoari Giorgio, Monti Carlo, Selvini Attilio, MISURA E RAPPRESENTAZIONE (in Italian), Casa Editrice Ambrosiana, Milano 2001.

Examination method

Oral test