In a previous blog post, we shed light on the process of constructing a digital building model from a point cloud. However, you might wonder why we opt for point clouds and what makes this method so efficient. In this article, we will provide a brief history of building surveying and delve into the significance of contemporary laser scan technology in our work.
The History of Building Surveying
Let's start with a brief, historical introduction to building surveying: Surveying buildings has been a long-standing practice, but the techniques and approaches have undergone significant changes over time. In the early days, simple tools like rulers and protractors were used to survey buildings, but these methods were not very accurate. In the 19th century, triangulation was introduced, providing a more precise way to measure distances and angles. However, even these method had their limitations in terms of accuracy and time required.
Over time, various surveying technologies have been developed and employed, such as the theodolite, tachymeter, or total station, which were mainly used in building surveying at the turn of the millennium.
Theodolites, Tachymeters, and Total Stations - Surveying in the 2000s
Theodolites and tachymeters are optical instruments that use light waves to measure angles and distances. They work by capturing the light beams emitted by the instrument and reflecting it back to the instrument to calculate the distance. On the other hand, a total station is a more advanced optoelectronic instrument that combines the functionality of a theodolite and a distance meter. While these instruments have provided valuable insights into building surveying, their drawbacks are also evident. The data captured by theodolites and tachymeters needs to be manually inputted into CAD software, which is time-consuming and requires specialized skills. Although total stations allow for immediate electronic processing of data, the measurement process is still time-intensive. In light of these limitations, building surveying has embraced laser scanning technology as a solution.
The Development of Laser Scan Technology
The development of laser scanners dates back to the 1960s, primarily for military and space exploration purposes. These early laser scanners were used to measure distances and to gather surface geometry information of buildings and landscapes. In the 1970s, scientists and engineers started exploring the possibilities of using laser scanners for civilian applications, specifically for surveying buildings and landscapes. This marked the beginning of the use of laser scanning technology in building surveying, providing a more efficient and accurate solution for capturing building information.
Laser Scanning to Point Cloud
During laser scanning, the laser scanner continuously emits a laser beam that hits the surface of the object being scanned. This reflected beam is then picked up by the scanner's receiver. The distance to the surface is calculated by measuring the time taken for the laser beam to travel from the output to the return. The angle coordinates are recorded in real time by an integrated theodolite system. The laser scanner repeats this process at different positions to gather additional measurement data. Upon completion of the scanning process, a large quantity of measurement data is collected and merged into a point cloud. This point cloud serves as the foundation for creating a 3D model and is imported into CAD software where 3D modelers use it to construct a digital replica of the building.
Point Clouds as a Precise Modeling Tool
Over the years, a variety of surveying technologies have been developed in the field of building surveys. Among these, laser scanning technology has proven to be particularly effective, as its accuracy-to-effort ratio is very high. By creating point clouds, millimeter-accurate digital 3D models can be produced, bringing us closer to reality than ever before. This aligns with the ongoing trend of sustainability in the construction industry.
Are you interested in the topic of 3D modeling (BIM) and want to learn more about it or do you have specific questions? We would be happy to have a conversation about it.
Michael Danklmaier, Miviso Co-Founder
Tel.: +43 664 4563309
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