INTRODUCTION

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In recent years, there has been a great advance in the development of techniques and technologies in the areas of civil construction, architecture, interiors, industries, among others. The methodologies used in structural and architectural survey work have undergone constant evolution in their planning and execution – especially with the emergence of new measuring equipment.

The use of 3D laser scanning allows for extremely accurate surveys, fast and with a reduction of rework and unexpected in the field. For this reason, we saw the opportunity to apply the use of this technology and other tools to capture reality to record historical heritage, since in addition to capturing the geometric dimensions with millimeter precision, it also offers a 3D digital replica, increasing the range of studies and analyzes that can be reproduced.

It created the need to validate what is important to document and register in a building of historical heritage and analyze the quality and accuracy that the data must have - since there may be an excess of information. Thus, through a case study, it was decided to carry out a survey of an old residence through the use of laser scanner, drone and 360 camera to analyze possible deliverables that facilitate the study of historical heritage.

For this case study, a partnership was established with student Julia Gabriely Campana – a student of the 11th semester of Architecture and Urbanism at UFSC – with the objective of disseminating the use of different technologies in capturing reality for the preservation of historical assets. The student will develop a restoration project for the Tamanini Family's residence, and to facilitate the survey process, studies of pathological manifestations, as well as a study of the impact of the house's neighborhood.

METHODOLOGY

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The case study was carried out at the Tamanini Residence – located in the city of Rodeio, in Santa Catarina – built in 1937, with Trentina immigration. With a self-supporting wall structure, the residence has traces of Italian architecture, consisting of four bedrooms, bathroom, large living room, kitchen, attic and basement. All furniture, floors and paintings have been preserved since its construction, thus enabling the owner to overturn the building and make it part of the city's tourist route.

For the survey of the residence, the WRodacki team went to the field in the late morning, with the objective of carrying out the survey with the drone at noon – the most suitable time for the flight. The day was sunny with few clouds, making it easy to survey the laser scanner, drone and 360 photos. The team performed the service in 4 hours, considering that all jobs were done simultaneously.

The laser scanner used is manufactured by Faro, model Focus S150, whose main features are a maximum range of 150 meters, 1mm accuracy in 20 meters, 360º horizontal and 300º vertical field of vision, autonomy of 4 hours / 1 battery and digital camera attached. It uses LIDAR technology, which as the equipment emits laser beams, the beams find the surface and return with information on the position and signal strength. Each point contains XYZ coordinates and the set of these points is called a point cloud. 3D laser scanning captures all surrounding surfaces and generates a 3D digital replica of the environment.

To perform the scanning, the scanner was placed outside the building in such a way as to take a scene every 12 meters, including photos so that the cloud would be colored. In the basement, the scenes were monochromatic and arranged according to the arrangement of the beams and arches, so that it was possible to capture the entire structure. For a greater volume of data, at least one color scene shot was made inside the house in each room, in addition to the monochromatic support scenes with low resolution on the doors – just to facilitate the union of points. In the attic and bathrooms, the scenes were high-resolution monochromatic, as they lacked details of paintings and different textures of materials.

To complement the point cloud generated by the survey with the laser scanner, the drone was used as support, in order to join the point cloud generated by the drone with the laser scanner cloud. This way, the cloud is complete as the scanner is unable to capture some roof information and coverage details – due to the angle required.

The drone used is a DJI brand, Mavic 2 Pro model with a 31-minute flight autonomy, with a camera sensor capable of recording 4k videos. In order to carry out the flight, it was decided to use control points on the ground, in order to unite with the laser scanner point cloud. The drone captures several images, and after processing these images in a specific software – Reality Capture – the point cloud is generated through photogrammetry. The union of the drone's point cloud with the laser scanner's cloud resulted in an estimated global error of 3.8 cm.

For the survey of colors and materials, the GoPro Fusion 360 camera was used with two cameras capable of generating photos in 18 megapixels and creating 360º videos in 5.2K at 30fps. In order to take the photos of the residence in the external area, the camera was placed in such a way as to take a 360º photograph every three meters. In the basement, it was made according to the arrangement of the structure's beams and arches, using the “night mode” function, since there was not much natural light in the environment. Inside the house, including the attic and the bathrooms, at least one photo was taken per room – increasing the number as needed and the amount of detail.

DEVELOPMENT

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The objective of this study is to be able to capture as much information as possible about the residence so that there is validation of what is important to document and register in a building of historical heritage and, for this, several products were generated.

From the 360 photos, a materials survey map was created, capable of identifying the colors present in the objects and in the detailed paintings of each room. Each image was analyzed by an application that can distinguish the color using the Pantone scale – providing numbering and nomenclature. In addition, a location map was made for each captured photo, for a better understanding of the building's layout.

The cloud generated by the survey with laser scanner and drone has numerous applications, as it is possible to create 2D documentation, 3D mesh model, As Is and 360 visualization of the entire building. For the Tamanini family's home, a file was generated in Recap – free Autodesk software – for viewing this cloud, with color captures from the scanner, cutting box, measurements and annotations. The file was also made available in Faro's Scene 2Go viewer, which does not need any specific program to open and allows viewing the point cloud, color photos and extracting notes and temporary measurements.

From the cloud, it was also possible to perform the As Is of the residence in Revit, entering information on materials, textures and quantities - being the most faithful to the existing structure and objects. The intention is that the academic can use this model as a basis for designing, as well as for proposing restoration changes. In addition, a textured 3D mesh model was created – a vector representation of an irregular or organically shaped object generated from a point cloud. It is a lightweight file, which can be used for visualization of the building, and as a basis for generating a mesh for 3D printing.

With the point cloud, it is also possible to generate an orthophoto of the model. This image is scaled and undistorted, making it possible to measure distances and identifiable objects on it. It can be created from any view or section of the building, being a simple and fast process. In addition, the photos and videos generated by the drone can help to study the surroundings and impact of the neighborhood, as well as to carry out simulations of solar interference.

The time for preparing the deliverables varied according to the degree of detail and difficulty of each file. Four days after the scan, the monochromatic and colored dot cloud was made available to the student with cleaning of the cloud noises; the scene2 go viewer; 360º photos with their mapping, survey of materials and orthophotos of the main facades of the residence. Two weeks after the first delivery, the textured 3D mesh and complete modeling of the house was made available in Revit - with material details and creation of families for each specific element.

CONCLUSION

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In the case study carried out, it could be concluded that the survey method with capture of reality using a laser scanner, drone and 360 camera - under the circumstances and conditions described - generated a large volume of high quality information. Regarding the validation of deliverables, the academic described that all the results obtained and the generation of materials carried out and delivered to her, were of high value for the academic work. In addition, the scan served as a historical collection for the city of Rodeio and the Tamanini family.

The documentary memory of historic buildings is extremely important for the restoration and preservation of these listed properties, and laser scanning can facilitate and speed up this process. However, it is important to emphasize that the use of the cloud is essential and indispensable to check measurements throughout the design, creation and historical archiving process, since in the modeling process it is not possible to preserve all dimensional variations captured by the laser and recorded in the a cloud.

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