GPS (United States)

It was the first fully operational GNSS and remains one of the most widely used globally. It has typically 31 operational satellites. It was created as an independent military navigation system by the Department of Defense (DoD). Before it was made public, great effort was invested into providing high accuracy as well as making it secure against jamming and spoofing attempts. GPS uses the L-Band frequency range of 1176.45 to 1575.42 MHz.

GLONASS

Russia’s Global Navigation Satellite System (GLONASS) is the second navigational system in operation with global coverage and of comparable precision to GPS. GLONASS is operated by the Russian government and became fully operational in 1995. The fully operational system consists of 24+ satellites. It operates in the frequency from 1202.026 to 1600.995 MHz (G1/G2) . In standalone applications, GLONASS doesn’t provide as strong of signal compared to GPS but is a great alternative/backup for GPS. Over the past ten years, Russia began replacing its second-generation GLONASS-M satellites with the more modern GLONASS-K design.

GALILEO

GALILEO is Europe’s GNSS system that is compatible with GPS and GLONASS. It was created by the European Union through the European Space Agency. It operates with 28 satellites. GALILEO provides 3 services

• Open Access Service: It delivers meter-scale accuracy to the public.
• Public Regulated Service: It delivers centimeter-scale accuracy to authorized users.
• Search-and-Rescue (SAR): It relays distress messages to European ground stations.

BEIDOU

BeiDou is the Chinese satellite navigation system, operated by the Chinese National Space Administration (CNSA).

The first generation was called BeiDou-1 and was mainly used by China and neighboring regions.

IRNSS/NavIC

The Indian Regional Navigation Satellite System (IRNSS), with an operational name of NavIC (Navigation with Indian Constellation), is an independent regional navigation satellite system. It is developed by Indian Space Research Organization (ISRO). It provides real-time positioning and timing services. It covers India and a region extending 1500 km around it.

What is a 3D Model?

A 3D model is a digital representation of a physical object or scene created using computer software. The process of creating a 3D model involves designing the shape and structure of the object using specialized software tools. Once the model is created, it can be manipulated and viewed from different angles to provide a detailed understanding of its dimensions and appearance. The main advantage of using photogrammetry is its ability to reproduce an object with an especially high quality of texture.

Understanding 3D Mesh and Textures

It is essentially a collection of vertices, edges, and faces that define the shape and structure of a 3D object. With 3D mesh, models can be created with intricate details that make them look realistic.

Applications

Different Formats

Certain file formats store various kinds of information about 3D models. The most common file types supported are:

• OBJ —Its full form is Object File. It is one of the more important file formats in 3D printing and 3D graphics applications. It stores 3D objects that contain polygonal faces, texture maps, 3D coordinates, and other object information.
  

• FBX — Its full form is Filmbox. It is a proprietary file format that can store information on a model’s geometry, texture, color, and other appearance-related properties. It’s mostly used when working with film and video games.
  

• 3DS — Its full form is 3D Studio. It is a proprietary Autodesk file format that stores geometry, animation, and basic information on the appearance of the model. The 3DS format is mostly used in academic, engineering, architecture, and production domains.
  

What is a Point Cloud ?

A point cloud is a set of data points in a three-dimensional coordinate system that represents the external surface of an object or a scene. A point cloud is a collection of points in 3D space, where each point represents a specific coordinate. Point clouds can be generated through various methods, including photogrammetry, laser scanning, etc.

How Point Clouds Enhance Drone Surveying ?

Point clouds play a pivotal role in enhancing drone surveying in several ways. Here are some key points explaining how they contribute to the effectiveness of drone-based surveying:

• Precision and Accuracy: The exceptional precision and accuracy provided by point clouds in drone surveying is one of the most significant advantages. Drones with LiDAR sensors or high-resolution cameras may collect millions of data points in a single trip, ensuring that even the smallest details are captured. This level of precision is crucial in applications such as land surveying, where every inch counts.
• 3D Visualization: Point clouds make it possible to create highly detailed 3D representations of surveyed locations. This not only provides a visually engaging picture of the world, but it also enables detailed investigation of structures, topography, and items. This 3D perspective assists architects, engineers, and urban planners in making educated construction, development, and design decisions.
• Rapid Data Collection: Drone technology is well-known for its speed and efficiency. This speed is increased when paired with point cloud data. Drones can swiftly capture broad areas, lowering data collection time and resources.
• Data Integration and Analysis: Drone-captured point cloud data can be readily incorporated into a variety of software applications for further analysis. This data can be used to extract features, detect changes, and produce accurate digital terrain models (DTMs) and digital surface models (DSMs). Point cloud data serves as the foundation for a variety of GIS (Geographic Information System) and CAD (Computer-Aided Design) applications, allowing for data-driven decision-making.

Applications

The combination of point clouds and drone technology has numerous applications in a variety of industries:

• Construction and Engineering: Drones outfitted with LiDAR may efficiently monitor building progress, check structures, and provide detailed as-built documentation in construction and engineering. This speeds up the construction process, ensures quality control, and aids in the detection and resolution of concerns.
• Agriculture: Drone point clouds help with agriculture by monitoring crop health, optimizing irrigation, and measuring soil quality. Farmers can use this information to make data-driven decisions that increase crop output, reduce resource waste, and lessen environmental impact.
• Environment Management: Drone-captured point clouds are useful for analyzing natural resources such as forests, wetlands, and coastal regions. This technology is used by environmentalists and conservationists to monitor changes in these ecosystems, track deforestation, and safeguard biodiversity.
• Archaeology: Drones equipped with point cloud technology are used to build detailed 3D representations of historical locations and relics. This contributes to the preservation of cultural heritage, archeological study, and careful documenting of significant historical monuments.
  

Different Formats of Orthomosaic Map

Point cloud data is often saved in a variety of forms to accommodate different applications and software tools. Here are some typical point cloud data formats:

• LAS (Lidar Aerial Survey): It is a standardized and widely accepted format for storing and exchanging lidar-derived point cloud data. It provides essential metadata and attributes, enabling accurate and detailed representation of the physical environment in a structured and interoperable manner, making it a key component in various applications, including topographic mapping, forestry management, urban planning, and more.

• LAZ(LASzip): The LAZ (LASzip) file format is a compressed version of the LAS (LIDAR Aerial Survey) file format used for storing LiDAR point cloud data. It maintains the essential attributes of LAS data but uses a more space-efficient compression algorithm. LAZ files are often used when storage or data transfer efficiency is a priority.

• ASCII: These formats are plain text and store point cloud data as a series of lines with space- or comma-separated values for X, Y, Z coordinates, and optionally, additional attributes such as intensity.
  

• PLY (Polygon File Format): PLY is a flexible format often used for both point cloud and 3D mesh data. It can store point clouds in ASCII or binary format. PLY files also allow for custom attributes and can be used for both point cloud and mesh data, making them versatile for 3D modeling applications.

• BIN (Binary Point Cloud Format): A generic binary format that stores point cloud data without any specific standardization. Its simplicity makes it a flexible option for applications that don’t require extensive metadata.

Applications

1. Mining: Orthomosaic maps are used in the mining industry for monitoring mine sites, managing stockpiles and prevent enroachment.
2. Agriculture: Precision agriculture relies on orthomosaics for crop monitoring, disease detection, and yield estimation.
3. Urban Planning: Orthomosaics are used for urban development and infrastructure planning, including land use zoning, road design, and utility mapping.
4. Construction: Monitoring construction progress, evaluating structural integrity, and analyzing terrain.
5. Corridor Mapping: Inspecting tracks and roads, planning and monitoring, plotting elevation changes.
6. Archaeology: Discovering and documenting ancient sites, burial mounds, and historical landscapes.

GeoTIFF (Georeferenced Tagged Image File Format): GeoTIFF is one of the most widely used formats for orthomosaic maps. It combines image data with geospatial information, allowing it to be precisely located on the Earth’s surface. This format is compatible with various Geographic Information System (GIS) software and is suitable for many geospatial applications.

The previous SOP only mentioned submitting the Digital Elevation Model (3D), i.e., Digital Surface Model and Digital Terrain Model. In the new updated SOP, it has been made clear that the Digital Elevation Model (3D), i.e., Digital Surface Model and Digital Terrain Model, should include the 100m buffer zone. The spatial resolution of the image has also been defined, which should be less than or equal to 15cm in UTM Projected Coordinate System and in Geotiff format.

Compared with the Previous SOP, the new updated SOP clearly defines the GCPs that must be submitted to IBM. The new updated SOP has divided the GCPs that must be submitted to IBM into three files.

1.                 The total GCPs DGPS Survey data, including permanent GCPs, must be submitted to IBM in GCS                      WGS-84 datum and UTM Projected Coordinate System in Excel Format.
2.                 The Permanent GCP data needs to be submitted to IBM both in GCS WGS-84 datum, and UTM                          Projected Coordinate System in Excel Format.
3.                 The plan of GCPs needs to be submitted to IBM in UTM Projected Coordinate System in shapefile                      format.

• In the new SOP, submitting the RMSE report in .txt, .doc, and .pdf format has been mandatory. Earlier, the RMSE report needed to be submitted only in .txt and .doc format.
• There are also major updates in the map of the mining lease area. More features have been added to the map that needs to be marked in the map before submitting it to IBM. The updated features are listed below.

1. 1. ML Boundary
2. 2. Topsoil stack
3. 3. Infrastructure
4. 4. Roads
5. 5. Railways
6. 6. Tailing Pond
7. 7. Effluent Treatment Plant
8. 8. Mineral Separation Plant
9. 9. Township Area
10. 10. Others to specify (Green Belt area)

In the previous SOP, the Boundary Pillar coordinates must be submitted in the shapefile and Excel format in Geographic Coordinate System and Projected Coordinate System. In the new updated SOP, the boundary pillar coordinates must be submitted in Excel format in GCS and UTM. Also, a plan of the leased boundary pillar coordinates also needs to be submitted in UTM and GCS in WGS 84 datum. Although here, two separate shapefiles for GCS and UTM must be submitted.

Finally, As per the previous SOP, the Drone Survey Log Sheet needed to be submitted only in the .doc format, while in the new updated SOP, it has been made clear that the drone survey log sheet needs to be submitted both in .doc and pdf format.

What is an SOP?

SOP stands for Standard Operating Procedure. A standard operating procedure is a document that contains step-by-step instructions and guidelines for employees to follow when performing a technical, repetitive process within an organization. SOPs are employed by a number of organizations to guarantee that tasks are carried out consistently, effectively, and with the least chance of error or omission.

1. Drone Agency Registration and Permissions

There is no need to register with IBM for drone survey in mines. Drone Agencies or the lessee can conduct the survey while following all the applicable rules, regulations and guidelines notified by DGCA. Check the Airspace map from the Digital Sky website. The drone airspace map is an interactive map of India that demarcates the red, yellow and green zones across the country.

Green zones are the unrestricted zones where drones can be operated without any permission

Yellow zones are controlled zones and the drone can only be operated after a permission from DGCA.

2. Drone Specification

Drones used for the survey should follow DGCA guidelines and should possess mandatory safety features as notified by DGCA from time to time.

3. Sensor/Camera Specification and output data resolution

5. Survey Area

The survey should cover the entire mining lease area capturing all mining, allied activities and 100m beyond periphery of the mine lease boundary to monitor the environmental impact and ascertaining any excavation therein. The flight path plan and the numbers of flights taken to cover the entire area shall be provided to IBM along with the output data. For leases having common mine boundary, the survey may be limited up to the lease boundary for the sides, the lease shares common boundary with another lease.

7. Drone Survey Time

It is advised to fly the drone in better conditions when the sky is clear and the sun is overhead to minimize the shadows in photographs. Do not fly the drone when it is rainy or windy.

Coordinate Reference System

Geographic Coordinate System (GCS)

While a spheroid approximates the earth’s shape, a Datum defines the position of the spheroid relative to the center of the earth. A datum provides a frame of reference for measuring locations on the earth’s surface. It defines the origin and orientation of latitude and longitude lines.

Whenever you change the datum, or the geographic coordinate system, the coordinate values of your data will change.