Geospatial services

ROAD MAPPING USING MOBILE LIDAR APPLICATION

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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.

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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.

Automatic Acquisition of 3D City Model

CONCEPT PAPER ON AUTOMATIC ACQUISITION OF 3D CITY MODEL
3D city
Introduction

Urban areas are bestowed with a variety of geo information. Some of this spatial information is virtual and some are very complex physical information. Virtual information includes administrative boundaries such as municipal boundary, electoral ward boundary, jurisdiction boundaries of various departments etc. Physical information includes transportation network, communication network, utility network, land use land cover features, hydrographic network etc. Any kind of city management needs a data base containing the spatial information. All queries related to a city or urban management system will definitely relate to some location or spatial reference. Though two dimensional maps are available for the purpose, 3D city viewing is rapidly gaining acceptance and application over the former in most of the smart city initiatives. Application of 3D city models ranging from sitting of tower locations of cell phone companies to micro climate, environmental, air pollution, architectural designs and urban heat wave analysis.

3D city models are digital three dimensional models of urban areas with all its features. These features include aforesaid virtual features as well as other physical furnishings such as buildings, land marks, vegetation, infrastructure landscapes and terrain. These features can be represented in spatial data base in the form of two dimensional as well as three dimensional features class. 3D city models are visually integrating various geo spatial elements to real world scenarios with all its complexities. Creation of automatic 3D city models involves preparation of data base based on the required level of details, storage of the same in a data base, construction and detailing of city models and visualization of the same through various application platforms.

Application of 3D city models

There is a verity of application for 3D city models. Unlike last decade where 2D data base were in focus, current decade witness 3D data base model applications in many developmental activities. Some of the key applications of 3D city models are listed below.

Master planning applications: 3D city models are an apt tool for the town planners. 3D city models will help planners from conceptual development stage to the completion and long term environmental impact assessment stage. The benefit of 3D city models in two planning is that it will reduce planning errors and hence monitory loss, it provides better visualization capabilities and hence monitoring is very easy. The most import part played by 3D city models in such application is that it will greatly reduced project delays. It can also add value as a depicter which can monitor illegal vertical growth of the city.

Spatial Database Infrastructure Applications: 3D city models are part of the spatial data base infrastructure of the region. Irrespective of the initial cost of preparing such data base, in the long term it will be the robust data base service in the back ground of all developmental activities. This will be a base data for further spatial data simulation and modeling. Site suitability analysis of roof top for solar panel installations, thermal emission analysis of buildings and urban fabric are some of such analysis.

Disaster Management applications: 3D city models are highly helpful in disaster management in terms of providing near realistic effected of the disaster. It can simulate fire, flood, bomb explosions etc and after effects on the same in urban infrastructure in place to a great precision. Such simulations will help administrators and planners in managing their rescue operations and resource mobilization.

Navigational applications: 3D building models and terrains will give a realistic display of the area for people navigating and crossing through the area. It is gaining widespread acceptance than simply looking at the locations. It can be act as a tool for intelligent transportation system.

Utility design applications: 3D city models will play a key role in designs of sewerage channels, railway line routing, highway routing, power transmission lines routing and other geo designs.

Archaeological applications: Historical buildings and cultural heritages can be modeled to a highest level of detail (LoD5) in 3D city models so that its intricacies will be preserved and will help in maintenance and repairing.

Decision support system applications: 3D city models can be aptly used by planners and managers to take informative decisions using interactive models.

Property management applications: 3D city models can be effectively used for property management and also for dispute settling tool.

Entertainment applications: 3D city models can be back ground and give virtual reality for gaming industry.

Preparation of 3D city model data

There are several kind of input used for preparation of 3D city models. These are ranging from very high resolution stereo aerial photographs to high precision lidar data to high resolution satellite images. The kind of input used and level of details (LoD) extracted are solely based on the requirement of 3D city model. Buildings are most important items in a 3D city Model. The LoD is mainly for the detailing of the buildings. There are five levels of standard LoDs and these are

  • LOD 0: 2.5D footprints
  • LOD 1: Buildings represented by extruded foot prints
  • LOD 2: Extruded foot prints with standard roof structures
  • LOD 3: Detailed building architectural design models
  • LOD 4: Architectural design models with interior designs

Type of data in 3D city Models

3D city models have much kind of data. These include but not limited to GIS data, CAD data, BIM data, and some of the non spatial data as attributes. GIS data is very much required for any 3D city model. Base maps, digital elevation models, digital terrain models, land use maps, and administrative boundary maps, road network data etc. are the GIS component of the 3D city model. CAD data play a key role in 3D city models. Most of the buildings with required level of details as mentioned above can be designed in a CAD environment. Other infrastructure such as railway network, road network and other utilities can be modeled in CAD environment. The outcome in the form of wire frames or surface models will add flavor to the 3d city models. BIM data will provide with one step ahead information of CAD data. The specifications of the buildings in the form of attributes can also be incorporated in CityGML data model.

Data Management

3D city models comprise a variety of data sets, in a variety of formats. So there cannot be a uniform data base schema for the same. The data base schema will be depending on the requirement and application of the models. The component GIS data sets can be raster rata sets as well as vector data sets. 2D raster data sets can be in .geotiff, .img, .jpg like format based on the rendering capacity of the hardware as well as software and internet capability. 3D models again in ASCII, tiff or obj format where common CAD, GIS and graphic software can render and display. Reliable data base management is a prerequisite for complex analysis and result derivation from 3D city models. So a relational data base is very much required for running and utilizing any 3D city models. In this relational 3D city models, hierarchically structured, multi scale data can be stored, retrieved and analyzed. For Updation of the 3D city model data based is also possible only through a relational data base. Also the relational data base should able to hold multiple formats of the data and its rendering. Open geospatial consortium standards and norms can be followed in 3D city models creations as well. Such data bases are referred as city GML

Visualization of 3D city models

One of the major challenges in automatic acquisition of 3D city models is its visualization and semantic rendering. Visualization is a challenge because component of a 3D city model will be mostly from different data sources such as geo data, GIS data, BIM, CAD etc. So a common frame work schema based on the requirement of the model need to be established beforehand through a relational data base. Visualization and rendering are based on the core functionality required through interactive application suites. Typically 3D city model rendering should be fast, scalable, and cost effective. In case of 3D geometry and 3D texture display a specialized algorithms need to be established. In general rendering can be service based or maps based. City GML will provide not only the visual 3D city models but attributes can also be viewed.

Service based rendering: This kind of rendering will based on data base architectures which runs on client applications which is external in nature. In this case all 3D portrayals of computer graphics and other GIS data sets will be the responsibility of the external application. This can be Open Geospatial Consortium (OGC) compatible. Services based rendering can be of Web 3D service or Web View Service. The former will be based on the client application which is converted the scene graphics and other geo data in 3D models and later is through server based services. In this case the server will generate 3D views which are uploaded on requested to screen and streamed based on the scale of rendering. Here client applications will generate 3D models and save in the server and rendering is not directly done by application.

Map based rendering: Smart 3D city models are following map based approach and render 3D visualization to any kind of platforms. In this case the 3D city model is arranged to a series of small tiles which enable automatic 3D rendering. Different levels of details of the model and pre arranged in a server which any number of concurrent clients can access. Map based rendering is more simplified in terms of data transfer and complexity of the 3D data models.

Building Information Models (BIM)

Buildings are the major and complex component of any of the city model data base. Building information model can be from simplest extruding footprints (LoD1) to very complicated architecture with interior designs (LoD5). Automatic extraction of buildings is possible from 3d laser point clouds and photogrammetric approaches. But through this kind of approaches only LoD1 and LoD2 is possible. For higher levels of details Digital terrain models and digital surface models are required. Operator interference and statistical approaches are required for higher level of details of the BIM.

Role of GIS in disaster management

Natural disasters and catastrophes bring to light major dares for federal controls and local authorities. Earthquakes, floods, cyclones, epidemics, tsunamis, and landslides have become of regular occurrence many parts of the world, continually taking a heavy toll of life and property. Under serious disaster conditions, the major task for establishments is the protection of life (both human and animal), property, and the dynamic life-supporting infrastructure necessary for disaster alleviation. To give an edge in preparing and management of disasters, GIS technology could provide a crucial inputs for preparing a decision support and management system for authorities at times of disaster-related crises.
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Over the past few eons, Space expertise and Geographic Information Systems (GIS) Applications have become obligatory part of the modern information civilization. As the frequency of disasters become more and more regular and penetrating, the demand for these technologies is swelling in order to save lives, to minimize economic losses and to build resilience of the disaster affected region. It is imperious that the policymakers and decision makers make determined efforts to widen and expand the use of space technology and GIS applications in catastrophe prone areas to diminish the effect of disasters.

ROLE OF GIS TECHNOLOGY
GIS technology is a crucial component of information, communication, and space technologies (ICST), enabled disaster controlling systems because it remains predominantly untouched during disasters unlike in the instance of both information and communication technologies which are based on ground arrangement are wide-open to natural disasters.

The scope of GIS in disaster administration is as follows:

  • A large volume of data can be collected.
  • Data collection can be focused across a widespread area.
  • Data accuracy can fit in to the purpose of application.
  • Transfer of data is more consistent and safe even during disasters.
  • Communication is faster in various locations.
  • Communication is reliable across a wide area and remote distances.

TECHNOLOGY OPTIONS
The wide continuum of ICSTs used in disaster alertness, alleviation, and supervision include:

  • Airborne Remote sensing;
  • Geographical Information System (GIS);
  • Global Positioning System (GPS);
  • Satellite navigation system;
  • Internet, e-mail; and
  • Special software packages, on-line management databases, disaster information networks.

Range of Applications
The following phases of Disaster management areas are the point of interest for professionals who hinge on ICSTs for critical solutions.

  • Database generation
  • Information assimilation and analysis
  • Disaster charting and consequence simulation
  • Hazard valuation and observing
  • Disaster tendency forecasting
  • Susceptibility assessment
  • Emergency response decision support
  • Logistics preparation for disaster relief
  • Needs calculation for disaster reclamation and reconstruction
  • Risk analysis and assessment

Data integration is one of the strongest points of GIS. In general the following types of data are required:

  • Data on the disastrous phenomena (e.g. landslides, floods, earthquakes), their location, frequency, magnitude etc.
  • Data on the environment in which the disastrous events might take place: topography, geology, geo-morphology, soils, hydrology, land use, vegetation etc.
  • Data on the elements that might be destroyed if the event takes place: infrastructure, settlements, population, socio-economic data etc.
  • Data on the emergency relief resources, such as hospitals, fire brigades, police stations, warehouses etc.

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When an emergency strike an area, the already amassed spatial data can be effectively used to combat the disaster. Unfolding impact influence area, marking of areas in harm’s way and mass notification can be possible through GIS. Optimizing shelters, routings, estimating effected population and property, assessing quantity of relief materials, advance warnings to nearby possibly affected areas etc will be ease out with the help of GIS
GIS will act as a central database repository during the recovery phase of a disaster. GIS coupled with remote sensing will act as an apt tool in assessment of damage and losses incurred. These kind of spatial data assessment give information on the extent of damage to individual properties and aerial coverage of the damage. This will enable the planners and decision makers to estimate the reconstructions cost, prioritizing the areas for development.

TREE COUNTING USING REMOTE SENSING TECHNIQUES

Operational administration of green assets such as forests and urban green cover ordinarily necessitates reliable, timely and well-run information about its developments and current status. Tree count management is important for sustaining conservational stability and ecological biodiversity. A systematic tree inventory of the forested areas and in the urban areas can help us involvedly view the causes of decline of forests in the area, decline in green cover in urban areas etc. and assist in decision making. Customary methods for counting trees are labor-intensive catalogue in the field or on an elucidation of large scale aerial photographs. Nevertheless these methods are pricey, time consuming and not pertinent to large, sequestered areas. Remote sensing technology know-how is the operational method for management and monitoring of green resources.
Polygon with tree point

There are different methods of getting the remotely sensed data, like the ones listed below.
1.LiDAR
2.Satellite Images
3.UAV/Drone Images
4.Terrestrial Photogrammetry

LiDAR
LiDAR methods of data collection is progressively used in forestry applications but also employed in urban environments for green cover calculations, tree canopy mapping and tree counting. Vast point clouds are usually converted software specific readable formats and are used to do the mapping for the tree counting and urban forestry mapping.
Tree Location and count

Satellite Images
One of the most important resources in the earth that needs constant monitoring and needs to be accurately measured for effective management is forest resources. Remotely sensed high-resolution or very high resolution satellite image data are crucial in this management, since it provides detailed information to administrators and planners for better decision making

UAV/Drone Images
Hyperspectral remote sensing, which uses the modern satellite sensors ability to capture the data in multiple-bands, in amalgamation with a properly updated land information system is understood to be a worthy technique to assist in making fast decisions. The practice of using Unmanned Aerial Vehicle (UAV) platform for many remote sensing applications is done to combine the advantages of traditional remote sensing techniques and the inexpensiveness of operating such techniques. UAV drones can fly at varying altitudes subject to the objective of the mission and end-result type. This tractability allows for optimization of the procedures according the meteorological conditions over a given area and the user requirements.

Terrestrial Photogrammetry
Tree counting is crucial for cultivated area and environmental management, biodiversity monitoring and many other applications. Regardless of the factor that satellite and aerial images have been widely used to distinguish, demarcate and count individual tree in urban areas and forested lands, till such techniques becomes widely accessible and knowledge of processing such data is increased, the traditional methods still hold the sway and might be detrimental for the green cover we all wish to have.

APPLICATIONS OF SATELLITE IMAGERY

Remote sensing data provides much essential and critical information for monitoring many applications such as image fusion, change detection and land cover classification. Remote sensing is an important technique to obtain information of earth resources and environment.
What popularized the satellite imagery are the open-access applications like Google Earth, BING Maps etc. From being simply able to find “where is my house” these applications have helped GIS community in project planning, monitoring disasters and natural calamities, guiding and helping civil defense people etc.

Remotely sensed satellite images comprise of spectral, spatial and temporal resolution. Spectral statistics is the substance of remotely sensed image classification. The main aspect which influences the accuracy of ground object is the Spatial resolution. Temporal Resolution will help in generation of land cover maps for environmental planning, land use change detection and transportation planning. Data assimilation and analysis of urban areas using medium resolution remote sensing imagery is mainly concentrated on documentation of built up areas or for judgement between residential, commercial and industrial zones.

There are 100’s of applications of Satellite imagery. From the days of Landsat’s and SPOT’s satellite imagery and when nations used to use information derived from the satellite imagery for spying on each other under the guise of scientific experiments, industry has grown in leap and bounds and today every sphere of life, government decision making, civil defense operations, police, you name the sphere of life, every one of which is influenced by Satellite Imagery in particular and Geographic Information Systems (GIS) in general.

SBL has pioneered in the field of Satellite Imagery processing and has got in-house expertise to handle any kind of sensor and product demands. Our projects have helped clients world over to help in having a better say in sustainability management and environmental assessment and management. An attempt is made and listed below to explain the uses of Satellite Imagery, even though the space given is not enough to cover all aspects of it.

1.Optimizing solar panel energy output with irradiance values.

Sustainable living has lot of interest in solar energy and it interest is growing rapidly across the world. Finding out location for placement of solar panels and If you were to choose a single position anywhere on Earth to install a solar panel, then we have to use Global Horizontal Irradiance (GHI) map. GHI measures the rate of total incoming solar energy at the Earth’s surface in watts per square kilometer. Epochs of satellite data (derived from GOES and Meteosat) has created this data with a standard error of only 5%.
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2.Generating Earth’s surface elevation with the Shuttle Radar Topography Mission

The SRTM digital elevation data, produced by NASA originally, is a major breakthrough in digital mapping of the world, and provides a major advance in the accessibility of high quality elevation data for large portions of the tropics and other areas of the developing world. The Shuttle Radar Topography Mission (SRTM) obtained elevation data on a near-global scale to generate the most complete high-resolution digital topographic database of Earth. SRTM consisted of a specially modified radar system that flew onboard the Space Shuttle Endeavour during an 11-day mission in February of 2000. SRTM is an international project spearheaded by the National Geospatial-Intelligence Agency (NGA), NASA, the Italian Space Agency (ASI) and the German Aerospace Center (DLR).

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3.Extracting mineral deposits with remote sensing based spectral analysis

During the pre feasibility and feasibility stages of the mineral exploration it is very essential to know the mineral potentiality of the area under consideration. In such scenario satellite remote sensing based lithological mapping, geological structural mapping, geomorphological mapping etc and its integration in a GIS platform will enable geo scientist to map the mineral potential zones. This will be further enhanced with the help of spectral analysis of satellite image bands to identify and map hydro thermal alteration zones which a indicators of mineral availability. This will enable exploration geologist to confine his geo physical, geo chemical and test drilling activities to high potential zones.

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4.Giving that a basemap for graphical reference and assisting planners and engineers

The amount of details that an Orthoimagery produced using high resolution satellite imagery is of immense value and provides an extreme amount of detail of the focus and surrounding areas. Maps are designed to communicate highly structured message about the world. As maps are location-based, aerial imagery supports people to orient themselves.

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5.Disaster Mitigation planning and recovery.

The result of a natural calamity can be calamitous and at times difficult to assess. But a disaster risk assessment is essential for rescue workers. This has to be prepared and executed quickly and with accuracy. Object-based image classification using change detection (pre- and post-event) is a quick way to get damage assessments. Other similar applications using satellite imagery in disaster assessments include measuring shadows from buildings and digital surface models.

2D Feature mapping from High Resolution Satellite images

Remote sensing is a vital system to acquire information of earth resources and environment. Remotely sensed images comprise of spectral, spatial and temporal resolution. The introduction of High-resolution satellite imagery is projected to reduce cost for medium and small scale topographic mapping. Since high-resolution satellite imagery has a much close-fitting field angle, the projection of images is nearly calculated by parallel rather than central systems. Using high resolution we can extract valuable information that will serve as a reference to bigger data needs and planning.

The feature extraction stage is intended to obtain a solid, non-redundant and evocative demonstration of observations. It is accomplished by removing repetitive and irrelevant material from the data.

satimageinterpretation

satimageinterpretation


SBL has perfected its capabilities in 2D feature mapping in the form of base mapping, land use land cover mapping and other types of thematic mapping. This kind of remote sensing services requires the knowledge of pre-processing on the satellite images. These pre-processing steps includes geo-referencing for geometric corrections and image enhancement for radiometric corrections. Digitally enhanced and geo-referenced images can be (re)projected to real world co-ordinate systems to put it in use for 2D feature extraction.
map digitisation

map digitisation

GIS data represents real world entities and features such as roads, land use, elevation, trees, waterways, etc. In GIS all features are grouped under the classes of point, line or polygons. Points are the smallest entity in GIS. Land marks, spot heights and point features such as locations of wells, ATM’s etc. can be represented in the form of points. Lines constitute a series of points called vertices and nodes with a start point and an end node point. Transportation network, drainage network, telecommunication lines, power transmission lines, sewerage network and other utility and transport networks can be represented in the form of lines. Polygons are closed features in which a line has start point and end point the same and which will encompass an area within it. Parks, water bodies, residential areas and forests can be represented in the form of polygons.

For 2D feature extraction services SBL will follow a classification schema derived after the requirement and need study established with the end-client. For example, for a forest department forest land parcels along with hydrographic and transportation network will be captured. For a mining firm during their replacement and rehabilitation process residential buildings, plantations, and orchards may be the main concentration. The thematic mapping using 2D features will be established as per the project and need requirements and is designed with a long term vision of serving the future changes and developments.

GIS mapping for 2D features extraction can be possible through aerial photographs as well. The features can be extracted using image interpretation keys such as tone texture, size, shape, association ext. SBL’s experienced image interpreters will deduce the images to useful thematic categories based on the classification schema. The final stage of the GIS based mapping services is the cartographic layout preparation. Each and every mapped 2D features will be given with a suitable standard symbology and layout can be prepared based on standard cartographic norms. The above notes explains in general the 2D mapping approach adapted by SBL.

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

Use of Airborne LIDAR in Transmission Line Projects

The growing energy demand is an issue that power utility authorities incessantly face. The creation of new transmission lines is not always probable due to complications in acquiring rights-of-way and obtaining environmental approvals. Airborne LIDAR uses a precise laser scanning technology that offers decidedly accurate terrain and tower elevation data for the transmission line corridor. The advanced software tools allow the analysis of critical distances, obstacles identification, slackness calculation, catenary shape calculation, and location of structures besides allowing data to be exported to specialized engineering softwares.
GIS plays an important role regarding operation planning, data maintenance and design of transmission lines. A great amount of data is required for the operation and maintenance of data related to transmission lines, which includes property ownership data, corridor land use/land cover (LULC), transmission line situation and characteristics. The physical features of the lines and corridor LULC are determined during construction but has to be updated due to the constant change in surroundings during the lifetime. Automation of technological procedures involved in data collection, integration and processing will ensure increased efficiency in the management of the utilities. Dispensation of the data discusses to the production of complete topographic GIS products including their custom-made presentation and analysis.
LIDAR (Light Detection and Ranging) is a contemporary remote sensing technique for the collection of high density and accurate topographic data, which allows high-speed and economical data acquisition of power utility networks. LIDAR together with GIS technology offers efficient tools for database management and analysis.

Fig 1. LIDAR components

Fig 1. LIDAR components

Further to range measurements, some LiDAR systems are also adept in registering the intensity of the backscattered laser pulse. Intensity is defined as the ratio of strength of reflected laser to that of emitted laser, and is influenced mainly by the reflectance of the reflecting object (Song, 2002). Reflectance deviates with material characteristics so that different materials have different reflectance. Therefore intensity images may be supplementary information for a LULC classification. The merging of intensity images with Elevation information produces an image where features can be easily identified. Intrinsic to the collection process the above mentioned images are ortho-rectified images facilitating in the collection of required data for a GIS System. These ortho-images can be used as location image references to maintain or to update an existing GIS database.

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Figure 2 – (a) Intensity Image (b) Image obtained by fusing intensity information with elevation information.

Results of the managed LIDAR data consists of 3D information about cables, structures as well as all hindrances along the corridor in a form of a point cloud with X, Y, Z coordinates and intensity value. Post-processing actions are needed in order to classify features and to develop additional information. Ground and cable points are categorized using algorithms available in TerraScan software.

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Among the non-ground points power lines strings can be captured using top views and need to ensure that it connects all the towers. This classification is the result of analysis by an automated filter developed which detects all LIDAR hits returns from the power lines and can be categorized as wires. Towers were also can be detected in a similar way. Critical points can be detected along the transmission lines and exact height needs to be assigned to each object. 50m either side of the transmission lines can be considered for object search and exact height of the objects can be derived. The objects encountered will be houses and vegetation in general. A vegetation clearance report will help to details location of the critical points and its complete information.
LIDAR technology provides a well-organized collection of high density and accurate topographic data, being one of the most recognized cost-effective and high-speed method to such projects. Above and beyond the obstacles and vegetation along the corridor, the location and height of the prevailing towers can be derived precisely. The high density of the laser points enables accurate delineation of the cables as well as the derivation of the connection points. LIDAR in concurrence with GIS methodologies provides efficient database updating and analysis.

3D feature extraction services

3D shapes have been functional in many fields, such as 3D City modelling, Terrain Visualization, industrial design, education, animation entertainment and preservation of historical sites, etc. Feature extraction of 3D shapes is an important branch of Geographical Information Systems using the advanced technologies like Digital Photogrammetry, LiDAR Data processing and pattern recognition, attracting more responsiveness from many technocrats. 2D feature mapping shows only horizontal features on a planar surface, without elevation contours to depict the terrain, whereas in 3D topographic mapping contour and elevations are vital parts. More importantly combination of Planimetric/Topographic Mapping is a depiction of the Earth surface features in 3D means and used for geospatial analysis and modeling.

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SBL’s 2D/3D Feature Extraction in-house expertise qualifies us to capture data from small to large scale stereo models and generate high precision digital topographic maps. SBL 3D feature extraction services provides accurate digital planimetric feature extraction for cartography mapping and 3D topo mapping by extracting surface features like railroads, buildings, hydrological features, vegetation, etc., with proper coding and symbology.
     Viewing the features extracted from the above methods and get superimposed on the 3-dimensional digital aerial photograph, ensures that editing and collection time is accurate and complete.
SBL’s ability to create customized databases and cartographic map representations is useful in meeting any specification or software format.

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The benefit of 3D features is the value-added geospatial information that can be derived from high resolution stereo images and hi-density point cloud data. This comprises three specific data products, not exclusively, Digital Orthophoto, digital terrain models and 3D vector data. Digital Orthophoto have turn out to be a standard constituent of base map data, and can be used for accuracy assessment, 2D vector digitizing and update, change detection and a number of other applications. 

AREAS INFLUENCED BY 3D APPLICATIONS:
     •Long Range Planning
     •BIM 
     •Utility Network Designing
     •Plant/Facility Planning & Management
     •Roadway Design
     •Utility Management
     •Landfill/Quarry Management
     •Topographic Surveys
     •Volumetric/Quantity Calculations

Parcel mapping through GIS technique

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A digital record of land parcels or plots is a necessity of modern day administration of any country. In general these data is available in old paper maps and cloth mounted maps which are poorly maintained. In modern era, with every aspect of life is going digital, it is imperative to get the parcel/plot boundaries also in digital form for effective administration and as part of the e-governance initiatives. Land administration will be much easier with parcel boundaries in digital parcel map or Cadastral map. The Cadastral map is one of the basic registers that administration at village, town, city and country can have.

SBL Geospatial Services division is having in-house experience and expertise in executing such GIS services. Geographic Information System (GIS) is an appropriate tool used in mapping parcel boundaries. First step in such mapping process is geo-referencing of the parcel maps after converting the paper maps into raster format by scanning method. The ground control points required to register scanned images to the ground is possible through field surveying, from other georeferenced maps, from open source data. Geo-referenced parcel map can be used digitize the parcel boundaries through heads-up digitization. The mapped objects can be point, line or polygon. Added advantage of parcel mapping in this way is that, one can incorporate any number of attributes to the digitized parcel boundaries. This will explicitly give ownership details, history of ownership, change details of the properties and any other relevant information deemed fit for the purpose.

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The digital parcel map is the vital component of any cadastral system and is used for legal, administrative and economic decision making and an irrefutable input for planning and development. One of the most important and basic benefit is that individuals can easily come to know about the area of land under their ownership and other details of their own property. This will help government directly by getting right amount of tax without any evasion due to poor record maintenance and difficult retrieval process of the same. It will greatly help urban development departments by assessing accurately parcels and properties affected by any developmental program and decision making will be much easier as we know the impact beforehand. Municipality planning will also be much easier with a digital parcel map, as the department is having accurate details of properties under its jurisdiction.

Most suitable GIS software, ArcGIS is nominated for carrying out the parcel mapping work. Besides digitizing, attribute assignment and management and geo database management, topology building and checks will be very easy in this software platform. Parcel mapping services also include mosaicking or seamless joining of adjacent maps so that village, taluk or district level data can be viewed and analyzed simultaneously. This will be highly helpful for the decision makers. Unlike paper maps and cloth mounted maps, digital parcel will be easy to analyze for area calculations and other statistics. The final results of the parcel maps can be represented in the form of ready to print maps by applying cartography techniques to the mapping process. Standard mapping symbology can be used to demote boundaries of parcels and other details thus mapped.

The paper or cloth parcel map was observed as a static, plain view of preselected areas, available at fixed scales, but due to the advances of the geospatial technology, it is now progressing into a dynamic, recurrently updated network of interconnected databases with large amounts of geographically referenced information linked to a comprehensive central digital parcel database.