Geospatial services

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

New Image

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.

GIS for Utility Mapping

Utilities intrinsically are laid out geographically over a large areas of a city, state or country. It’s a demanding task to organize the information, develop and maintain the concomitant assets and infrastructure which are in a form of connected networks. GIS technology supports in making more intelligible databases of the network by placing the assets accurately on Maps and thus making it easier to identify and manage with ground truth visibility.
SBL provides utility mapping services in the following domains:

  • Electric Power Lines
  • Telecommunication Networking
  • Oil and Gas
  • Municipal Utilities
    • Waste Water
    • Storm water
    • Water supply lines
  • Traffic Utilities
  • Railway Utility Mapping

utilitty-mapping

SBL Geospatial Services has been in the forefront of assisting national and international clients with their specific utility and asset mapping. SBL possess in-house capability to understand, map and analyze any kid of utility mapping requirements. The multi-technology approach that SBL uses in their utility mapping services, by the means of LiDAR mapping, Aerial and UAV photography, Satellite imagery and paper to CAD conversion, has helped large private and government organizations in tuning their decision support and making systems to be robust, accurate and responsive.

GIS utility mapping services offers a collective platform to access data, manage assets, update utility network information, incorporate work orders, find customer information, and prepare reports.

Accurate and precise network mapping is well-thought-out to be a vital aid in building, planning, refurbishing and maintaining all consumers and assets of a Utility. The GIS datasets gets cohesive with all proven modeling software tools, ERP and MIS applications, SCADA systems, thus encompassing the usage of GIS technology further than just mapping.

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.

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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.

UAV DATA PROCESSING FIELDS OF APPLICATION

UAV data processing

UAV data processing


This write-up intends to present birds eye view of fully automated and accurate mapping solutions based on ultra-light UAV imagery. We showcase interesting observations in the field of UAV mapping, the steps to analyze the accuracy of the automated processing on several datasets. The software used to process is one of the leading and evolving software in the UAV data processing domain.
The accuracy highly depends on the ground resolution (GSD) of the input imagery. When chosen appropriately this mapping solution can compete with traditional mapping solutions that capture fewer high-resolution images from airplanes and that rely on highly accurate orientation and positioning sensors on board. Due to the advancement of computing practices and processing prowess of computers and careful integration with recent computer vision techniques, the result is robust and fully automatic and can deal with inaccurate position and orientation information which are typically problematic with traditional techniques.
SBL’s geospatial team is one of the first in the region to process such images. Processing of UAV images has its own challenges. SBL used to receive post-processed UAV images along with IMU and GCPs as input. Aerial Triangulation is the first step performed. During this stage Ground Control Point (GCP) and Actual Check Point (ACP) reports has been generated. This is an iterative step till we get desired accuracy. The following will explain in brief some of the critical steps in the processing of UAV data.

  1. The software examines for matching points by analyzing all images. The software used here an improved version of the binary descriptors, which are very powerful to match image points quickly and accurately.
  2. Those matching points as well as estimated values of the image position and orientation provided by the UAV autopilot are used in a bundle block adjustment to reconstruct the exact position and orientation of the camera for every acquired image.
  3. Based on this re-establishment the matching points are corroborated and their 3D coordinates calculated. The geo-reference system is WGS84, in this case, based on GPS measurements from the UAV autopilot during the flight.
  4. Those 3D points are interpolated to form a triangulated irregular network in order to obtain a DEM. At this stage, construction of a dense 3D model increases the spatial resolution of the triangulated data.
  5. This DEM is used to project every image pixel and to calculate the geo-referenced ortho-mosaic. The ortho image will be devoid of positional and terrain displacement inaccuracies.
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    One of the major application for which UAV images used are for agriculture. UAV images are ideal for small size farms. Plant counts such as corn counting will give an idea of yield from those plants. Plant health monitoring, differentiating species of agricultural farms/plants and plantation estimation are the major task performed for agriculture. Growth stages of the farms can also be monitored using ortho images acquired through UAV process. UAV image processing is also helpful for the site selection for solar farms.
    In case of forestry, UAV images are very helpful in species identification. SBL’s interpreters have identified forest species and enabled the client to map forest land parcels. It is a tool to monitor de-forestation as well as afforestation. Golf courses are another field where UAV data sets are highly useful. Golf course features can be mapped with their actual heights through this process.
    Mining industry is the most benefitted in the usage of UAV technological advancement. As most of the mines are spread over small areas, UAV data acquiring and processing is very cost effective. Along with other data processing, SBL has got the expertise in generating contours and mining related features to very minute levels of detail.