Laser Scanner of Piazza Rondanini - Architectural and Geometrical Drawings

GEOMETRI CDRAWI NG RONDANI NISQUARE-ROME

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RONDANI NISQUAREKEYPLAN

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COURSE:Ar chi t ect ur a Sur vey

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GEOMETR C DRAW NG -P AZZA RONDAN N

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Group: A dona B akaj Mar i ana Fer nades

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Dat e:21/ 02.

2022

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TABLE 04

ARCHI TECTURALDRAWI NGS RONDANI NISQUARE-ROME

40m

RONDANI NISQUAREKEYPLAN

39m

38m

37m

36m

35m

31m

33m

32m

31m

Sect i on BB

Sect i onAA

Sect i on CC

72m

COURSE:Ar chi t ect ur a Sur vey

Sect i on DD

73m

74m

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ARCH TECTURAL DRAW NG -P AZZA RONDAN N

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Group: A dona B akaj Mar i ana Fer nades

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121m

122m

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126m 127m

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Dat e:21/ 02.

2022

134m

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TABLE 04

LASER SCANNER WORKFLOW RONDANINI SQUARE - ROME The Laser Scanner method for survey have became one of the most important instrument and methodology to survey in the contemporary days due to its high accuracy.

How does it work?

First, laser scanning systems throw out light waves that bounce off of surfaces and reflect back to the sensor. Through the process called “time of flight” measurement. Then, the sensor calculates how far away the surface is of the building, for instance, is by measuring the time taken for the light beam to complete its journey.

The distance measured is then used to calculate a coordinate for the tiny section of the surface hit by the laser beam. All of this happens in just seconds, and during a single scan, a laser scanner will collect millions of 3D coordinates.

When the point clouds from laser scans are processed, they form a digital representation of the scanned surfaces, demonstrating the dimensions and spatial relationships of topographic features and structures.

WORKING WITH RECAP PRO - AUTODESK REGISTRATION REPORT First, in order to create the project, you can import a file or a folder, it depends on which type the dataset was created. The Recap will create then two elements, an executive file and a folder, and them both have always to be together. If it is the case to import a folder, is one folder per time and later the software merges all files in the same point cloud.

Following the Alignment Phase, there is three important parameters to analyses, the overlap, the balance and the points on distance.

- Overlap: is the most important parameter since it shows how many points are overlapping between the different data captured - Balance: is related to the 3D features of the object. This value is lower when there is no much information, except by a horizontal plane since this type of scan can be more imprecise and not much accurate. But if instead the space there is more vertical and horizontal planes to use as references, then is possible to obtain a much more accurate result and the balance value is higher - Points distance: this last parameter refers to how many points have a distance that is bigger than 6mm between different clouds , the same correspondent points. Is also important to highlight that the points always have a distance between them, however, should be the minimum as possible and definitely not bigger then 6mm.

After loading the second scan, is possible to preview the overlapping proposed by the software on the circle. If the circle color is red, means that the result is not really good; if yellow, something in the middle and green is the best result you can obtain with the overlapping.

POINT CLOUD ALIGNED, LOCATION OF THE LASER SCANNERS

RGB VISUALIZATION

ELEVATION VISUALIZATION

INTENSITY VISUALIZATION

NORMAL VISUALIZATION

SCAN LOCATION VISUALIZATION

After the phase of data capture, you can find all the data in folders. Is important to observe that each company will work with a different file format, and in the case of the FARO FOCUS 3D Laser Scanner used for this study case, the format is .fls. However, when necessary to interchange the point clouds from different softwares, a good option is to export in .e57, accepted in the majority of softwares that works with this dataset.

Image Source: Research Gate.

Available <https://www.researchgate.net/figure/The-functionality-of-terrestrial-laser-scanners-Function-Laser-Scanner-nd_fig1_320729709> Accessed in: February, 2022.

at:

THE ALIGNMENT PHASE When we make a laser scanner data capture, we have a center of projection which is the device itself. In this case, the Reference Coordinate System has a specific 0, 0, 0 point: it corresponds to the center of the device.

In order to align together different laser scanner point clouds, you have to rotate and translate the second Coordinate System (from the second point cloud) so to have an overlapping of the two point clouds (or more).

Roto translation of points: the operation of alignment of coordinates of two or more point clouds.

The software will give 3 options: skip registration, auto register and manual registration. The best choice is the third option, which the software will make an initial analysis of what can be overlaped and proposes a solution. Then is up to you to decide if is good enough or not.

Is also important to observe that this feature of controlling the alignment carried out by the software only can be executed if the version of the software is PRO and not the normal RECAP.

Finally, at INDEX (scans) Phase, the software is registering the location of the scans and reseting the point cloud so to change the coordinates of all the points of the second point cloud (and others if there is more). When Launch Project appears, it means that the software finished the configurations and it's finally possible to work on the 3D point clouds. And is in that moment that is possible to edit the point cloud so to see the many different types of representation exemplified here in this table.

MARIANA_CRISTINA_FERNANDES_PINTO_FRANCO_AND_ALDONA_BLACKAJ

ARCHITECTURE_SURVEY

MATRICOLA:1999764 LASER_SCANNER_WORKFLOW_TABLE

PROF.CARLO_BIANCHINI_AND_PROF.MARIKA_GRIFFO SAPIENZA_UNIVERSITY_OF_ROME

A1 03/07