Until now, three-dimensional measurement of buildings was time-consuming, expensive and error-prone. However, with the latest generation of 3-D laser scanners, data capture is easy, accurate and fast – at an affordable price. Entire buildings and their fixtures can now be completely and accurately translated into digital models. The new laser scanners capture up to one million measurement points per second with millimetre accuracy. This enables the detailed, high-resolution documentation of buildings. Dimensional deviations are small and fall within the DIN tolerances required in the building industry.
The Rechenbach architectural office in Hannover uses 3-D measurement with laser scanners to great advantage when documenting existing building inventory. A high level of efficiency and the fact that the method also removes the necessity for multiple building measurements are unbeatable arguments, as far as the designers are concerned. At the same time, the risk of expensive design errors is significantly reduced.
An illustration of this: Rechenbach's architects were able to measure a 1500m² industrial plant in Hannover in around an hour with the help of laser scanning. All the data was captured within this astonishingly short timeframe, and it was even possible to create a 360° panoramic view.The scanner software immediately delivered dimensionally accurate and spatial geometric analyses of the project, which were then used to create accurate building inventory documents. These formed the basis for the subsequent renovation work on the plant, for which several alternative uses were being discussed. Direct import of the scan data into popular architectural software solutions – such as AutoCAD from Autodesk, Revit Architecture, 3D-Studio Max Design or Bentley´s Microstation – greatly simplified the design work: the precise, three-dimensional point cloud model could be visualized inside the familiar CAD environment very easily. In addition, the previously time-consuming, external data preparation was no longer necessary. The costs approximately matched the level of a classic 2-D survey.
If a design has to be prepared in the 2-D line model using 3-D scanner data, the point cloud can be stored as a distortion-free and dimensionally-accurate image using software. After import into any CAD software, a vector-based 2-D design can be produced over this background image. Thus any number of floor plans, sections and elevations can be extracted from the 3-D data. As a further example from the Rechenbach office demonstrates, the reverse construction of a 3-D design from a 2-D model is also easily carried out with the appropriate software. In designing an energy efficient renovation of a façade using Revit Architecture, it was possible to use the scan data to plan the new window and façade elements accurately and incorporate them into the building structure. The architect was subsequently able to represent different material variations for the façade with easily generated renderings. Animations or videos from any viewpoint and virtual tours of the property using the stereoscopic navigation of the spatial model were also used to support communication with the building’s owner in a very graphic fashion.
Spatial building models have numerous advantages over the classic 2-D building inventory. Since all the information is present in three dimensions in the spatial model, multifunctional applications are possible. The range extends from simple dimension and area calculations to the previously described stereoscopic navigation in virtual buildings. The scanner captures the entire visible make-up of buildings and building components. This produces seamless records which can then be put to interdisciplinary use. Information that is not required for the current application can be deleted to expose important details and limit the file sizes. As a data basis for Building Information Modelling, spatial building models provide indispensable information for designers and facility/portfolio managers, as well as owners.