The Budapest company CÉH Inc. it was required to measure the building of the Hungarian State Opera House and create a detailed computer model based on them. By combining the principles of geodetic surveying with point cloud technology, the specialists were able to cope with the colossal task before them without disrupting the operating mode of the opera. The model obtained in this way will be used in the future to develop a project for the reconstruction of this architectural monument and its subsequent operation.
Building of the Hungarian State Opera House
130 years of history
The decision to build the building of the Hungarian State Opera was made in 1873. Based on the results of an open competition, the jury selected the project of the famous Hungarian architect Miklós Ybl (1814-1891). Construction of the neoclassical building, which began in 1875, was completed nine years later. The grand opening, to which the Emperor of Austria and King of Hungary Franz Joseph was invited, took place on September 27, 1884.
Built by Miklos Ibl, the acoustics of the opera house, which has remained virtually unchanged over the past 130 years, continues to attract art lovers from all over the world. Thousands of tourists visit the Hungarian State Opera House every year, considered one of the greatest architectural monuments of the 19th century in Budapest.
Measurements
The challenge for CÉH was to carry out full-scale measurements not only of the main building of the Hungarian State Opera, but also of other related buildings (shop, sales center, warehouse, rehearsal room, offices and workshops). Based on the points obtained in the process of measuring the clouds, it was required to create an architectural model that fully reflects the current state of all buildings.
The collected data were processed in the Trimble RealWorks 10.0 and Faro Scene 5.5 applications.
It is important to note that the direct data acquisition took much less time than their subsequent processing, because despite the fact that the data was processed almost immediately, the complexity of the building required increased attention in the process.
The combination of simultaneous measurement and processing created some additional difficulties. Each new part, presented in the form of a point cloud, had to be placed in a single model and linked to all previously placed elements in it. Moreover, there was simply no time to repeat measurements or change elements, so all operations had to be performed very accurately the first time.
It should also take into account the fact that the measurements were carried out during the operation of the opera. The need to gradually vacate some warehouses or provide access to certain premises led to the fact that measurements started in one part of the building continued in another part of the building, and then specialists returned to previously inaccessible premises. Of course, such an organization of work reduced the speed of their implementation and required additional coordination of the entire process.
"The GRAPHISOFT BIMcloud solution was a huge help in our work, providing good speed access to files from almost anywhere in the world." - Gábor Horváth, Lead Architect, CÉH
Although the measurement technicians had enough positioning tools, at first the opera staff accidentally moved these devices, seriously hampering the process of mutual alignment of the point clouds. However, over time, both teams learned to interact and not interfere with each other in their daily work.
Some rooms (such as props warehouses) were constantly changing, while the surfaces of other rooms (for example, a suspension system covered with metal mesh or backstage structures) were extremely difficult for geodetic instruments - all this required additional measurements.
The most difficult and laborious were the measurements of the vaulted and zigzag surfaces present in the technical and auxiliary areas at the lower levels of the building. It was also difficult to reproduce the vaults dividing the building into levels according to the plan of its author, Miklos Ibl.
Supports and other structures often overlapped the surfaces of walls and floors. In such situations, the measurement results could only be used to create a very rough 3D model. Therefore, to obtain more detailed information about the places inaccessible to a 3D scanner, video and photographic recording was often used.
Measurement datasets were previously imported into Faro Scene 5.5 and then transferred to Trimble RealWorks 10.0 for final processing. This process took quite a long time, since the processing of the point cloud files created in this way required a lot of processing power.
Point Cloud Library Management
File sizes are very important in data management. During the measurement process, a huge number of point clouds were created, and the detail of these files reached 40 million points per room. Files of this size simply could not be brought together. The first step was to reduce the number of points using Trimble RealWorks. Then, when the file detail was reduced by an order of magnitude, it became possible to combine these clouds, each of which already contained about 3-4 million points.
Optimized and merged blocks of 20-30 million points were saved with a resolution of no more than one point per square centimeter. This point density was enough to create a detailed model in ARCHICAD.
A single optimized point cloud file was exported in E57 format compatible with architecture software. Thus, the team of architects was able to start modeling directly.
The main part of the model was executed in ARCHICAD 19. At the same time, the use of the GRAPHISOFT BIMcloud solution, which provides an acceptable speed of access to files from almost anywhere in the world, played a significant role in the work. This factor was very important, because the size of the project exceeded 50 GB.
Working on the model
When analyzing the three-dimensional volume of the building, the old dimensional plans were initially used. These 2D drawings have been significantly refined and enhanced with point clouds.
Major discrepancies with older plans were apparent from the outset, with additional complications arising when comparing multi-level floor plans. In 1984, the building underwent a partial reconstruction, as a result of which some elements were replaced, for example, the steel supports of the suspension system. The documentation released for this reconstruction was very useful when recreating a model of complex design solutions, in which there were rather thin elements that were not perceived by 3D scanners. The same was true for movable structures such as the steel elements of the stage, which continued to be used during measurements.
Almost all geometry was created in the ARCHICAD environment. Very complex elements such as statues were modeled in third-party applications and then imported into ARCHICAD as triangulated 3D meshes. These elements, which consisted of a large number of polygons, were added to the model only at the last stage.
The greatest constraints on the architects were the computing power of computers, as the size of the point cloud files and the model had a slight impact on performance. To reduce the size of the model and improve the convenience of working with it, it was very important to minimize the nested library. In small projects, the size of this library does not play a big role, but in this case it contained many high-poly elements that greatly increased the size of the project and, as a result, created an excessive load on computers. To improve the smoothness of 2D navigation and reduce file sizes, some elements have been saved as objects. Thus, it became possible to place any number of instances of the same object in the model without creating new morphs or other structural elements. Even more optimization was achieved by simplifying 2D object symbols. Of course, this decision could not affect the 3D performance in any way, since it did not reduce the number of polygons present in the model. This problem was solved by adjusting layer combinations, for example, by disabling the display of decorative elements and sculptures during 3D navigation.
Many hours of work and tremendous effort resulted in the creation of a model that anyone can view on their mobile device. Detailed planning and stage-by-stage organization of the entire work process played a significant role in achieving success.
It is also worth noting that it became possible to efficiently carry out measurements and create an accurate model based on them only thanks to the well-coordinated work and readiness for interaction between the Hungarian State Opera and CÉH employees, who made a lot of joint efforts to preserve and reconstruct this magnificent architectural monument.
Opera House Model in BIMx Lab
Despite the fact that the ARCHICAD model has been optimized as much as possible, it still contains about 27.5 million polygons and approximately 29,000 BIM elements.
BIM models of this size are very difficult to view in the GRAPHISOFT BIMx mobile app.
But the recently created BIMx Lab technology perfectly copes with such tasks, which allows you to process almost any number of polygons in ARCHICAD models of any complexity!
Download the BIMx Lab mobile app from the Apple App Store.
To evaluate the possibilities of this new technology, download a model of the Hungarian State Opera building for the BIMx Lab.
About CÉH Inc
CÉH Planning, Developing and Consulting Inc. Is the leading engineering department of the CÉH Group, a key player in the Hungarian design and construction market. With over 25 years of experience, CÉH has amassed extensive experience in the design, construction and operation of buildings.
CÉH employs specialists from all engineering specialties associated with the construction industry. CÉH has around 80 employees, 10 branches and 150-200 contractors.
The area of BIM projects implemented by CÉH exceeds 150,000 m².
Architects CÉH Inc. have been using ARCHICAD in their work for over 10 years. CÉH currently owns 26 licenses and uses GRAPHISOFT BIMcloud. This project, carried out in ARCHICAD 19, consisted of three to seven architects on a continuous basis.
About GRAPHISOFT
GRAPHISOFT® revolutionized the BIM in 1984 with ARCHICAD®, the industry's first CAD BIM solution for architects. GRAPHISOFT continues to lead the architectural software market with innovative products such as BIMcloud ™, the world's first real-time collaborative BIM design solution, EcoDesigner ™, the world's first fully integrated energy modeling and energy efficiency assessments of buildings, and BIMx® is the leading mobile application for the demonstration and presentation of BIM models. Since 2007, GRAPHISOFT has been part of the Nemetschek Group.
