Longitudinal Sectioning

Longitudinal sectioning, also known as profile leveling or profiling, is the process of establishing the elevation of sites on the ground at about regular intervals along a continuous line. Profile levelling is one of the surveyor’s most typical applications of running levels and vertical distance measuring. The data are represented as a profile, which is a representation of a vertical cross section. The primary objective of longitudinal sectioning is to determine the slope, grade, and vertical alignment of the surveyed feature.

• Taking elevation measurements: At regular intervals along the base line, surveyors measure the elevation of the ground surface using an instrument like a leveling instrument or a total station. These measurements are recorded to create a profile of the land.

• Plotting the profile: The collected elevation data is plotted on graph paper or entered into specialized software to create a longitudinal section. The resulting graph shows the variations in ground level along the surveyed line.

Cross Sectioning

Cross sectioning involves the creation of horizontal cross-sectional views of the land perpendicular to the alignment being surveyed. This technique provides valuable information about the terrain’s shape, dimensions, and features at specific locations. Cross sections are particularly useful for designing and analyzing infrastructure elements like roads, canals, or embankments.

• Establishing cross-section lines: Surveyors mark perpendicular lines to the alignment being surveyed at regular intervals. These lines are known as cross-section lines or station lines.

• Taking measurements: Along each cross-section line, surveyors measure the ground level at predetermined intervals using leveling instruments or total stations. Additional measurements may be taken for features such as buildings, utilities, or natural elements.

• Plotting the cross section: The measured data is then plotted on graph paper or entered into specialized software to create a cross section. The resulting diagram provides a detailed view of the land’s features and elevations along the surveyed line.

Applications

Longitudinal and cross sectioning have numerous applications in surveying and civil engineering projects:

• Road construction: Longitudinal and cross sectioning techniques are extensively used in road surveys for designing alignments, establishing grades, and determining cut and fill quantities for earthwork calculations.
• Drainage systems: The creation of longitudinal and cross-sectional profiles helps in designing efficient drainage systems by identifying the natural flow patterns and locating appropriate points for channeling water.
• Utility infrastructure: Surveying utilities, such as pipelines or electrical cables, using longitudinal and cross sectioning helps in planning their alignment, estimating trench volumes, and identifying potential conflicts with existing infrastructure.
• Land development: When planning residential or commercial developments, longitudinal and cross-sectional surveys provide valuable information for site grading, building placement, and determining drainage patterns.

Benefits

• Accurate data: These techniques allow surveyors to gather precise elevation and terrain data, providing a solid foundation for engineering design and decision-making.
• Efficient design: Longitudinal and cross-sectional surveys facilitate the design of infrastructure elements, enabling engineers to optimize grades, alignments, and earthwork quantities.
• Enhanced visualization: The graphical representation of longitudinal and cross-sectional data helps stakeholders visualize the project’s topography and understand its impact on the construction process.
• Conflict identification: By identifying potential conflicts, such as steep slopes or underground utilities, early in the surveying process, longitudinal and cross sectioning help avoid costly design revisions during the construction phase.

Longitudinal and cross sectioning techniques play a vital role in surveying, providing valuable data for civil engineering projects. The detailed profiles and cross sections derived from these surveys aid in optimizing alignments, grades, and earthwork quantities while minimizing conflicts and ensuring efficient project execution.

What is a photogrammetry software?

Photogrammetry software is a computer program that provides the tools for performing photogrammetric measurements, such as loading photos from your camera and producing accurate measurements, maps, and models from those photos. In drone technology, photogrammetry sensors are typically high-resolution cameras that take pictures from various angles while flying over the area of interest. A 3D point cloud of the terrain or object is then produced by stitching together these images using specialized software. This point cloud can then be further processed to create a full 3D model, allowing anyone to view it from any angle as if they were physically holding it in their hands. The software to process these images can be desktop or cloud-based.

Cloud-Based Photogrammetry Software

Cloud-based photogrammetry software refers to applications that leverage cloud computing resources for processing and storing data related to photogrammetry. Cloud-based survey software makes it easier for companies to create surveys and receive responses quickly, making the entire process cost-effective. Compared to locally based solutions, cloud-based survey software doesn’t require a particular computer as it can be used online using a web browser.

Salient Features of cloud-based photogrammetry Software

• Data Upload: Users can upload their images or datasets to the cloud platform for processing. The software may support various image formats and offer tools for organizing and managing the data.
• Data Processing: The cloud-based software uses powerful computational resources in the cloud to perform photogrammetric processing tasks. These tasks include feature extraction, image matching, triangulation, dense point cloud generation, and mesh reconstruction.
• Automation and Optimization: Cloud-based photogrammetry software often includes automated processes and optimization algorithms to streamline the photogrammetric workflow. These features help improve the accuracy and efficiency of data processing.
• Visualization and Analysis: The software lets users visualize and analyze the photogrammetric results once the processing is complete. This may include viewing 3D models, orthomosaics, digital surface models, and point clouds, measuring distances, area, and volumes, and extracting specific information from the data.
• Collaboration and Sharing: Cloud-based platforms often provide collaboration features, allowing multiple users to access and work on the same datasets simultaneously. They also enable sharing and distribution of processed data through online galleries, sharing links, or embeddable viewers.

Pros

• Cost-effective: Cloud-based photogrammetry software follows a subscription-based pricing model, allowing users to pay for what they need when needed. This eliminates the need for significant upfront investments and provides more predictable costs.
• Time-saving: Cloud platform reduces risk and automates manual tasks.
• Accessibility: Cloud-based software allows users to access their photogrammetry tools and projects from anywhere with an internet connection. This flexibility benefits remote collaboration, fieldwork, or accessing projects on different devices.
• High accuracy and detail: Cloud Photogrammetry software can produce highly accurate and detailed 3D models and point clouds with high-resolution images and appropriate processing techniques.
• Flexibility and scalability: Photogrammetry software offers flexibility regarding the type of imagery it can process, such as aerial or ground-based photos, and can handle large datasets. Cloud-based solutions often offer scalable processing power and storage. You can easily handle large datasets and complex projects without investing in expensive hardware upgrades.
• Storage and Data Security: The data can be accessed anytime, anywhere since the data is stored in the cloud. There is no risk of losing the data.
• Collaboration: Cloud-based platforms enable real-time collaboration and data sharing among team members or stakeholders. Multiple users can simultaneously work on the same project, facilitating efficient teamwork and feedback exchange.
• Automatic Updates: Cloud-based software providers can release updates and improvements seamlessly without requiring users to install them manually. This ensures users can access the latest features and enhancements without additional effort.
• Integration: All outputs can be downloaded and exported to third-party CAD and GIS software for further analysis.

Cons

• Internet Dependency: Cloud-based software heavily relies on internet connectivity. If you have a slow or unreliable internet connection, it can hinder your ability to upload and process large image datasets efficiently.
• Data Security: Storing data in the cloud may raise concerns about data security and privacy. It’s essential to ensure that the chosen cloud provider has robust security measures and complies with industry standards and regulations.
• Data Transfer and Upload Times: Uploading large image datasets to the cloud can be time-consuming, particularly if you have limited bandwidth. This process may introduce delays before you can start processing your photogrammetry projects.
• Limited Offline Functionality: Cloud-based software generally requires an internet connection to access and use the tools. If you work in an area with limited connectivity, you may be unable to work on your projects or access your data.
• Dependency on Service Provider: When using cloud-based software, you depend on the service provider’s availability and performance. Any downtime or technical issues on their end can impact your ability to work on your projects.

10. Data Output and Formats

The outputs that need to be submitted are discussed below:

11. Submission of Data to IBM

The processed output data of the drone survey shall be submitted in soft copy only in storage media (i.e., external hard disk) on or before 1st July every year along with the Output data submission form at the following addresses.

1. The Chief Mining Geologist, Indian Bureau of Mines, GM&MM Cell, 1st Floor, A- Block Indira Bhavan, Civil Lines, Nagpur- 440001, Maharashtra
2. Respective Regional Offices Indian Bureau of Mines

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.

Mission

The primary mission of Indian Bureau of Mines is to promote systematic and scientific development of mineral resources of the country (both onshore and offshore), through regulatory inspections of the mines, approval of mining plans and environment management plans to ensure minimal adverse impact on environment.

It has been proposed to use a combination of digital aerial (Drone and satellite) images to monitor mining activities in the country. In mining, drones have various applications like mine surveying, inventory management, stockpile evaluation etc.

Ministry of Mines has incorporated Rule 34A in the Mineral Conservation and Development Rules 2017 for submission of digital aerial images of mining lease areas to Indian Bureau of Mines

What is MCDR?

The MCDR have been framed under section 18 of the Mines and Minerals (Development and Regulation) Act, 1957 [MMDR Act] to provide rules regarding conservation of minerals, systematic and scientific mining, development of the mineral in the country and for the protection of environment.

KML Boundary Extension

As per IBM, the drone survey should be conducted upto 100 metres outside the lease boundary. If you are confused on how to increase the lease boundary, you can extend your original KML boundary using the KML Boundary Extension free tool from this website.

Enter the website and upload your orginal KML boundary. At the top right corner input the distance in meter upto which you need to extend the boundary and click submit.

Data Collection

Linear Mission

Linear missions are used to survey roads, corridors, canals, etc. It is used to analyze line-type features. The default mission shape is a line. Here you can increase the lines according to your mission, place them accordingly, and start the mission. Once the area is marked, and the altitude and lines are set, the drone will automatically fly to the initial point and begin its mission. After reaching the endpoint, it will return to its home position.

Circular Mission

Buildings/Monuments are mapped using the circular mission. It takes a circular flight path, allowing it to capture images from all angles. Once the area has been marked, and the altitude is set, the drone will fly to the initial point and begin its mission. It returns to its home position after reaching the endpoint.

How to fly in mines?

Drones in the mining industry are a pragmatic solution to fix daily problems and play a role in reducing human risk, inspections, and repair costs while also increasing efficiency. However, we must exercise caution when flying drones in mines. When compared to traditional ground surveys, aerial surveys have the upper hand.

To get a good field of view, use the Polygon mission and keep the camera facing the ground.

How to fly in hilly areas?

It is possible to fly a drone in the mountains. However, you may encounter challenges in exceptionally high mountains because the air is less dense at higher elevations. Additionally, you can have shorter flight times due to a more considerable drain on your batteries caused by altitude and cold.

Points to note before flying

• Be aware of your surroundings.
• Fly at high altitudes and increase overlap to identify areas with critical features.
• Keep an eye on the weather, especially the wind.
• Choose a safe elevated area as the home position.

How to fly when there are tall trees and dense vegetation?

Drone technology redefines forestry’s components and contributes to forest ecosystems’ development and improvement. It also contributes to wildlife monitoring, Tree disease Detection, Forest fires, etc.

Points to note before flying

• Fly at high altitudes to ensure you have a clear line of sight.
• Place GCPs in areas where the terrain abruptly changes.
• Set the minimum height above ground to the tallest object’s height + 25m.

How to fly when it is windy?

Most drones can fly in strong winds, but it depends on the specifications of your drone.

Points to note before flying

• Maintain a safe distance from buildings and other obstacles.
• Check the wind speed of the site before flying the drone.
• If the drone becomes unstable, try to land as soon as possible or use the return home feature.
• Fly the drone in the wind’s direction.
• Some drones will have fail-safe features, such as an automatic return-to-home feature when the wind speed exceeds a specific limit. If this occurs, do not attempt to fly the drone again.
• Keep a close eye on the battery.

• The GCP points should be spread out evenly throughout the map so that the raster data is geo-referenced properly.

• The GCP should be clearly visible and unobstructed.
• A minimum of 3 GCPs are required.

What if Printed Banners are not available?

1. You can use black spray paint on a white background and mark the GCPs using the “X” sign. Also, make sure to mark a number next to each point to assist with identification at the time of processing.
2. If spray paints are not available, you can always use Lime or similar stuff to mark on the ground.

How is GCP measured?

Surveyors use a surveying instrument known as DGPS (Differential Global Positioning System) to place on the center of the GCP point and note down the accurate data and preserve it in the logbook.

Why do we need GCPs?

GCPs can be considered reference points. To know why we need GCPs, we need to know what accuracy is.

Accuracy is how close a given set of measurements are to their true value.

There are two types of accuracy:

Absolute accuracy is derived from comparing the position of real-world point data to the position of the data points within a processed map. For example, the absolute accuracy is high if a point, let’s say, a house or a road is matching the exact location with the real-world data.

GCP Accuracy

With the help of any Photogrammetry Software, we can get a detailed GCP report. For those of you who are not familiar with what RMSE is, Root Mean Square Error or RMSE is used to measure the difference between 2 values or datasets. Here the first dataset is the error value obtained from the GCP points in the ground and the second dataset is the error value obtained after processing in the Photogrammetry Software.