Terrestrial laser scanning - a modern method of collecting and recording of spatial data. In contrast to traditional survey methods (using a total station or satellite receiver), where the performer is forced to choose the characteristic points of the object, for subsequent displaying, scanning the object allows to automatically register the coordinates of points on its surface at a set period. Moreover, the scanning speed can reach more than 1,000,000 points per second, and the density of the resulting "point cloud" -hundreds of thousands of points per 1 sq. meter. The point coordinates accuracy, depending on the scanner model and distances, is within the range of a few tenth of a millimeter to a few millimeters.

Terrestrial laser scanning is used to address a wide range of tasks, from creating measurement drawings and 3D models to performing classical surveying of complex industrial facilities.

Depending on the details of a specific project, ground scanning can be performed as an independent operation, as well as in combination with other types of surveying: tachymetry, mobile and airborne laser scanning.

The "NIPIStroyTEK" staff-member specialists have a lot of experience in projects based on the use of terrestrial laser scanning technology, as well as a wide range of the state-of-the-art scanning equipment.

Terrestrial laser scanning

Main applications:

  • Power Industry(creating three-dimensional models and topographic maps);
  • Architecture and Urban Planning (creating three-dimensional models and measurement drawings of buildings and city blocks, three-dimensional GIS);
  • Oil and Gas, Metallurgy and Heavy Industry (creating "as-built" three-dimensional models of industrial enterprises, «as-buildt» layouts);
  • Mine surveying (computing quantities of earthworks, DTM and three-dimensional models of quarries and pits);
  • Roads and railways (creating three-dimensional models of infrastructure, roads certification, GIS, "as-built" survey, creating a longitudinal or transverse profiles);
  • Archaeology and monuments (creating three-dimensional models of objects and architectural monuments, creating measured drawings and cross sections).

 

Advantages of the technology:

  • Remote sensing eliminates staff access to dangerous areas;
  • High accuracy and detail of the data provided;
  • High performance data collection;
  • Easy creation of detailed three-dimensional models;
  • Significant cost savings compared with traditional surveying methods.

 

Depending on the objectives of the project, survey teams or institutions use the Surphaser 25 HSX high-precision phase scanner (0.2 mm to 100 meters), or Riegl VZ-400 pulse scanner with an accuracy of 0.5 cm, but the maximum range of up to 600 m.

 

More information on Terrestrial laser scanning:

Description of TLS Technology
Types of Outputs
Equipment

Description of TLS technology

Terrestrial laser scanning technology is used to obtain the geometric parameters of the object and is based on the spatial coordinate’s measurement of points on its surface. Using phase or pulsed laser rangefinder and a goniometrical device, the device measures the distance and direction of the laser beam, and the built-in software recalculates the values measured in the three-dimensional coordinates.

Depending on the model and the mode, the scanner performs a few thousand to more than a million measurements per second. Rotating mirror or prism produces a scanning beam deflection in the vertical plane, hence supporting the vertical seep of the scanner. Scanner rotation on its axis at a given speed produces the horizontal deflection of the scanner beam. The end result is the so-called point cloud. (Fig. 1). The density of such a cloud depends on the distance to the object and scan time, and it can reach tens of thousands of points per square meter.

Figure 1. The point cloud obtained from a single scannerposition.

High-density of data produced by TLS (distance between adjacent measured points can be up to several tenths of a millimeter) provides information on every detail of the object.

Most terrestrial laser scanner models are equipped with a built-in calibrated digital camera or a camera mounted on a special bracket. The use of photographic images facilitates colorizing laser reflection points in the true colors for easy readability and scan data can be used to further texturing (Fig. 2).

Fig. 2 Photographs-based colorizing of point clouds

Fig. 2 Photographs-based colorizing of point clouds

The scanner measures the coordinates of points in its own conventional coordinate system (with the accuracy of up to 0.2 mm, depending on the model), so that for each single position of the device we get a separate point cloud. After that, the data from different sites are registred (integrated into a single geometric space and referenced to the desired coordinate system. Accuracy adjustment (association) of point clouds is few millimeters. Measurements from several positions allow ruling out the shadow zones produced by interfering objects or caused by the absence of sight to different parts the object. The combined point cloud carries complete visual and geometric information about the subject and is used for a wide range of applications..

Outputs

Terrestrial laser scanning technology has been around for over 10 years and is constantly evolving. Industry experts over the years have learned to apply such scanner-based data to a wide range of applications. Due to the constant development, there are new techniques and methods of data recording that can meet the growing needs of the market.

Topographic map

Use of terrestrial scanner to create topographic plan, reduces the field work several times, and the completeness of the data minimizes the probability of the lack of any required information, thereby increasing quality and decreasing turnaround time. The raw scan data can be used to facilitate control functions or in the event of disputes.

Fig. 3 Topographic map 1:500 designed by laser scanning data.

Fig. 3 Topographic map 1:500 designed by laser scanning data.

Point cloud

Typically, the raw scan data (point cloud), are the source material for creating topographic maps, drawings, 3D modeling, etc. However, it should be noted that the information contained in the laser points colorized using the photography (see Figure 2), is the most accurate, complete and reliable. In the development of any product, whether a topographic plan or a3D model, what matters, apart from the cost of the materials, is the inevitable loss of the details that may be useful to the customer. Raw scan data can be imported into popular CAD systems such as AutoCAD, Micro station, AVEVA, Intergraph, etc. There are many tools to work with point clouds. Any geometrical measurements, surfaces creating, fitting solid elements into the construction, and designing sections, make up a non-exhaustive list of applications, enabled by the use of the advanced software. In addition to specialized functions, it is quite possible to use the standard tools with reference to the laser points.

 

 Fig. 4 Point cloud application to the Microstation environment

Fig. 4 Point cloud application to the Microstation environment

 Fig. 5 Point cloud based section construction in the  AutoCAD environment

Fig. 5 Point cloud based section construction in the AutoCAD environment

The main advantage of using point clouds is the relative cheapness and efficiency of their production, as well as a high degree of detail.

Given that modern laser scanners can operate at speeds of up to 1.2 million measurements per second, single scan position takes just a few minutes, while surveying an industrial area of up to 5 ha can be performed in one working day. The density and the accuracy of the data are several times higher than the same obtained with the use of traditional survey. The use of point cloud makes redundant the modeling process, which, normally, consumes the lion's share of time and labor. Besides, the simulation process implies data generalization, therefore, part of the information is omitted, while the point cloud retains the entire amount of data.

Drawings, sections, layouts

Among the products developed on the basis of the data produced by the laser scanning are the classic two-dimensional drawings and cross sections. Appropriately designed, they are clear and familiar to most professionals. Project reporting documentation is, also, delivered in the form of drawings. The accuracy and completeness of the scanned data, efficiency of their production can increase the quality and reliability of the results.

Fig. 6 Laser scanning based “as-built” survey

Fig. 6 Laser scanning based “as-built” survey

Three-dimensional models

One of the main products generated on the basis of laser scanning data is the three-dimensional model. Specialized software is used to create solid-state or polygonal models, including the DTM. The solid-state models are further used either as the basis for a three-dimensional design, or as material for GIS generation. Similarly to the cloud of points, a solid-state model carries complete geometric information about the object, but can be supplemented with parametric data.

The laser scanning data are also used to develop models of industrial enterprises, city blocks, architectural monuments, civil engineering facilities and more.

Fig. 7 Three-dimensional solid-state equipment model for a gas pumping unit

Among other things, three-dimensional models are commonly used in the animation or in architecture, for the simulation of emergency situations or designing security systems for a company.

 Fig. 8 Three-dimensional modeling of structures for a railway bridge

Fig. 8 Three-dimensional modeling of structures for a railway bridge

 Fig. 9 Three-dimensional model of the Kazan station in Moscow

Fig. 9 Three-dimensional model of the Kazan station in Moscow

Equipment

Terrestrial laser scanning is an accurate, complete and safe method of collecting data with the scales of 1:1 - 1:500. Measurements are made at the rate of up to 1,200,000 points per second. Obtained with a pulse or phase terrestrial laser, the "point cloud" is space oriented based on the GPS data or using geolocation referencing provided by the desired coordinates system.

A terrestrial laser scanner scans all the visible elements within a radius of 0.5 m to 600 m. The scan data can be reduced to a single three-dimensional "point cloud", which serves the basis for the construction of a high-precision 3D-model.

The "NIPIStroyTEK" LLC offers a full range of ground-based laser scanning operations and 3D modeling of objects.


Model

RIEGL VZ-400

Surphaser 25 HSX

Уникальность

remote control, high accuracy and density, low noise, ultra-high speed scanning

высокая точность и плотность, низкий уровень шума, сверхвысокая скорость сканирования

Laser class

Laser Class 1

Laser Class 3R

Maximum possible measuring range for natural targets ρ>80%

600 m

140 m

Maximum possible measuring range for natural purposes ρ>10%

280 m

N / A

Minimum possible measuring range

1.5 m

0,2 m

Accuracy
Noise level

5 mm
3 mm

0,3mm
0,07 mm

Scan speed

122,000 points per second

up to 1.2 million points per second

The field of view scan

100°*360°

270°*360°

Degree of protection

IP64

 


Weight

9.6 kg

11 kg

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