After deciding on the reconstruction of a building, design organizations begin to collect initial information: archive drawings, survey data, measurement plans, point clouds.
- Archived data. This is the easiest way to find out information about a building. However, often archived data can be lost or they can lose their relevance due to numerous reconstructions and redevelopments.
- Survey data. During the renovation of buildings, a survey is a prerequisite for further design. During the survey, data are obtained on the bearing capacity of the elements, visible and invisible damage to structures.
- Measurement plans. They are obtained using simple measuring elements such as a tape measure, vernier calipers, and so on.
- Point clouds. It is a modern method of obtaining the dimensions of a building and its elements. A point cloud is an array of points data with their coordinates, color, and reflection intensity.
After receiving this data, you can start designing. However, if the design will be entered in a three-dimensional environment, it would be more optimal to combine all the data into one measurement model.
To carry out the reengineering of the complex of buildings for «Incarnation», IM Сonsult was provided with measurement models, point clouds, and classic drawings.
The purpose of the reengineering was to obtain a basis for further design and create a unified database of reconstruction objects.
Questions arising during the performance of work
Combining all types of information into a single model.
In the course of collecting initial data, the customer immediately applied 2 methods of collecting information: in-situ measurements and laser scanning.
Laser scanning was carried out only outside the buildings to obtain complete information about the facades of the building, as well as linking the buildings to each other. As a result, the scanning turned out to be point clouds of all reconstructed buildings outside (Fig. 1)
Figure 1 Point cloud of building facades
Inside the buildings, measurements were made using the classical method using a tape measure; as a result, measurements were obtained (Fig. 2) and sections (Fig. 3)
Figure 2 Measurement plan
Figure 3 Measurement section
Laser scanning is a more accurate measurement method than the classical tape measure, and the main difficulty in this project was precisely in linking the drawings and point clouds. Also, the problem was aggravated by the large length of the building, because due to an error even by a tenth of a degree, the error in the coordinates can be up to 10 centimeters.
To solve this problem, we had to make some concessions. To begin with, we identified the most critical areas in which one cannot deviate from measurements by even 1 millimeter. The plans were taken as a basis, they are at least less accurate, but for the design the position of the supporting structures is much more important than the rotation of the outer wall by half a degree. Since the facade model was already modeled from the point cloud (Figure 4), we continued working in a new file and attached the existing facade. However, to achieve the continuity of the model, the outer walls had to be adjusted.
Figure 4 building facade model
As a result, 4 building models were obtained, which are completely ready for further design. It is also possible to enter survey data into this model to create a single information field.
Figure 5 section of the finished building