Tag Archive: lidar services

ROAD MAPPING USING MOBILE LIDAR APPLICATION

3

Management of road networks and its associated assets is a huge task for all transportation agencies around the world. The traditional ways of collection of data was time consuming and the productivity of the staff was at the best average. With the advent of new technologies like Mobile LiDAR Mapping, the collection, assimilation, analysis, design, construct, maintain and storage of data has become very fast, accurate and cost sensitive This dynamic system of mensuration can be used to acquire highly accurate and compact 3D statistics by safely driving a gathering vehicle at public road speeds

Mobile Lidar systems is made up of of four different devices: a laser, a scanner, a photodetector and a GPS/IMU positioning system. These four systems assimilate to measure the distance to an object by lighting the target with throbs of light from the laser instrument and gauging the time it takes for each throb to bounce back to the sensor. For the reason that light moves at a persistent and known speed, the distance between the laser instrument and an entity can be measured with a high degree of accuracy. A briskly firing laser can cover entire scenes in a few strokes, visualizing the topography and extracting data. A highly capable processing software then transforms raw data into colorful 3-D point clouds, and the end results are multifaceted, high-resolution maps.

Collection of detailed, high accuracy street-level data of street framework is expedited by having instruments capable of reading GPS/IMU on a automobile platform, achieving immense extents of GIS-friendly LiDAR point cloud data in short amount of time. Terrestrial LiDAR system is competent to see data flanked by buildings and under tree canopy, which airborne systems, will never be able to capture. Mobile mapping systems usually collect a full 360-degree FOV at a speed of 30-40 kilometers per hour. The data collected will be highly precise and can be used to generate convincing 3D data and highly accurate road maps.

2

Geo-referencing factor of mobile mapping is akin in idea to airborne platforms, but distinctive in run through. It is not possible to keep the GPS lock all the way through an entire mobile survey. The mobile platform must be able to traverse, and accurately map, below tree canopy, under bridges, without loss of positional accuracy. The IMU system become judgmentally important. The airborne system necessities for GPS/IMU quality basically do not apply in these situations.

As is the case with every mapping application, supplementary imagery and substantial data post-processing is often crucial to producing GIS or CAD-compatible final products. The processing applications necessitate solid surfaces with unambiguously defined edges, and topologically-structured feature objects (points, lines, and polygons) with widespread data description and attribution. The time and effort involved in taking out these features from LiDAR point clouds has been a process only knowledgeable persons can work out. This needs special LiDAR/Point cloud processing software and custom data formats, as is for airborne or fixed systems, transfers over to mobile systems and is augmented by the steep quantity and intricacy of the data acquired.

Incorporation of mobile mapping data, generating exhaustive data for highways and metropolitan infrastructure) with mobile topographic LiDAR survey generated terrain models and oblique imagery is sure to turn into the gold standard for street mapping and visualization in the very near future.

SBL UK to partner with Ordnance Survey at major construction event.

uk-event
SBL’s UK division is delighted to have been selected by Ordnance Survey – the UK’s National Mapping Agency – as an exhibitor Partner on their stand at Digital Construction Week in London. In conjunction with IDC, we will be showcasing how Ordnance Survey map data products can be maximised through innovation.

The event takes place between 20th and 22nd October. Please feel free to visit us at the OS stand – M42 – for a demonstration.

We will issue a more detailed communication closer to the event. In the meantime further information can be found here:

http://www.digitalconstructionweek.com/home

LiDAR DATA PROCESSING AND ASSET MANAGEMENT

LiDAR(Light Detection And Ranging):A form of representation of 3D surfaces, Point cloud data, are usually produced by aerial or terrestrial laser scanning, also known as Light Detection and Ranging (LiDAR). The data is produced as sets of very dense (x, y, z) points or in a more common, binary format called LAS that may include values of multiple returns and point intensities. Many leading GIS processing software’s now accommodate and supports basic and advanced LiDAR data processing and analysis. LiDAR is emerging as one of the cost-effective and accurate data capture system to manage large assets such as Railway stations and other public/private infrastructures.
SBL GIS Services division has been in the forefront of processing LiDAR services for some time now. Our LiDAR data processing services has been entrusted with prestigious and complex Infrastructure modelling projects across many geographies. One such example is demonstrated in the picture given below.

Picture1
Fig-1: All visible data captured as vector data with the help of Terrestrial LiDAR scanner point cloud data related to this project and attributed to their respective code. The above view is illustration of the output.

The Science behind LiDAR Working
LiDAR working is quite simple and it works on the principle of Light – speed and time taken to reflect the same from a surface. The distance is calculated from the difference between the time when a beam of light hits a surface and measure the time it takes to return to its source. Light travels very fast – about 300,000 kilometers per second, or 0.3 meters per nanosecond so we feel the instantaneous result when a light is turned on. The paraphernalia required to measure this needs to function extremely fast. Only with the advancements in modern computing technology has this has become possible.
Distance = (Speed of Light x Time of Flight) / 2

USES OF LiDAR MAPPING.
One of the main focus of LiDAR services in the Urban Infrastructure Mapping.

Urban Infrastructure Planning  
Urban Planning or City development is the science of land use planning which considers several aspects of the as-built data and social environments of the area of interest. LiDAR Mapping is a moderately new technology for obtaining Digital Surface Models (DSMs) and Digital Building Models. This data, when combined with orthorectified images, can create highly detailed Surface Models and eventually 3D City Models.
Wayside assets include tarmacs, streetlights, signs, advertisement boards, traffic signals and street furniture. A thorough understanding of all the assets, what they are and where each asset is located, is crucial to the development of an asset portfolio.
An accurate record of all assets along the transportation network is vital to asset management, to plan a maintenance schedule and budget costs. A bigger challenge than developing the asset database is keeping it up to date and this is where the cost-effective, accurate LiDAR Mapping will come into play.

Rail Utility mapping and digital asset preparation from 3D point clouds

Light Detection And Ranging (LiDAR) technology provides most accurate input data source for utility mapping. High accuracy, operation from multiple platforms, and ability to survey through tunnels makes this technology unique for rail utilities. Lidar data can be acquired in discrete patches and later register to get a complete 3D point cloud of the rail corridor. Hence data handling and processing will be faster when comparing with other technologies. Another added advantage is that its feasibility to get minute details of the intricate features. Ability to collect RGB values along with intensity makes this technology most relevant for 3D model preparations. This will be of great help to rail engineering, designing and maintenance and constructing organizations. So survey grade spatial information can be collected in a faster pace with this kind of data. More over this data can be processes in multiple software platforms like Auto CAD, Leica Cyclone, Terra, Micro station and combination of these.

Picture1

Digital rail asset mapping

The mail application of lidar survey in rail utility mapping area

  • Condition assessment of tracks and switches
  • Digital rail asset register preparation
  • Signage management
  • Vegetation encroachment monitoring
  • Corridor monitoring
  • Corridor design
  • Corridor maintenance
  • Kinetic monitoring

Sample Gantry

Sample Gantry

Rail right of way area is an asset intensive corridor. So mapping these corridors is labor intensive. SBL has got the technical capabilities to map, capture features and model them in a 3D environment for various design and maintenance activities. In a recent project SBL geo spatial team has collected an exhaustive list of more than 100 features related to rail assets. These are ranging from base structures to huge bridges. Presentation of output files in various 3D models pertaining to rail assets was one of the peculiarities of the project. SBL has prepared the data in 3D wire face model, 3D surface model, MX GENIO format as well as in lexica true view formats. Initially all the features were captured as wire frames and later converted to surface models. A digital terrain model of the area has been created by classifying the data to ground and non ground categories. Trimming adjustment with digital terrain models were performed to bring the features to ground level and to obtain accurate height of the features.

Sample electrical structure

Sample electrical structure

Challenges of using lidar data in rail corridor mapping are a). Possibility of features missing due to low intensity of the point clouds, b). Masking of the features due to presence of debris, c). Blockage of features due to presences of temporary articles present over the area and d). Registration related issues.

Sample over bridge

Sample over bridge

Rail operators are benefited in using such kind of data due to

  • It provides a complete digital record of all assets
  • Change detection is very easy
  • Encroachment of vegetation, unauthorized occupation and missing of features can be monitored
  • Condition assessment is very easy
  • Standard maintenance programme can be implemented and managed effectively.
  • Alternate and optimal routes can be established for new tracks and yards
  • Prefeasibility studies will became easy