Surveyaan: Drone Survey & Mapping Solutions - Blog #orthomosaic map

LiDAR Surveying and Drones: What is Lidar Drone Survey ?

Wed, 02 Jul 2025 12:07:46 +0000

In the fast-evolving field of geospatial technology, LiDAR surveying using drones is transforming how we map, measure, and manage the Earth’s surface. Whether it’s infrastructure planning, surveying, mining, forestry, or topographic mapping — LiDAR-equipped UAVs (Unmanned Aerial Vehicles) are becoming indispensable tools for professionals across industries.

In this blog, we’ll explore what LiDAR drone surveying is, how it works, its benefits, applications, and why it is a game-changer for modern surveying.

Quick Question Before We Start:
Have you ever used a drone for work or fun?

What is LiDAR Surveying?

Imagine a technology that can see through trees, map ancient ruins, and even help self-driving cars navigate — that’s LiDAR!

LiDAR (Light Detection and Ranging) is a remote sensing technology that uses laser pulses to measure distances. These pulses are emitted from a LiDAR sensor, bounce off surfaces, and return to the sensor, allowing it to calculate the precise distance between the object and the sensor. When mounted on a drone, LiDAR can collect millions of points per second — creating highly accurate 3D point clouds of terrain and structures. LIDAR is an ideal system for a variety of industries, including the civil engineering, roadwork and mining industries.

What is a LiDAR Drone?

It is simply a UAV (Unmanned Aerial Vehicle) equipped with a LiDAR (Light Detection and Ranging) sensor.

How Does LiDAR Drone Technology Work?

1. Laser Pulses: The LiDAR sensor sends out rapid laser pulses — often hundreds of thousands per second.
2. Return Signal: The laser hits a surface (ground, building, tree) and reflects back to the sensor.
3. Distance Calculation: The time it takes for the laser to return is used to calculate the exact distance.
4. 3D Model Creation: Combining all these points, software generates highly detailed 3D maps, called point clouds.

This process allows surveyors to generate accurate Digital Elevation Models (DEMs), Digital Terrain Models (DTMs), and Digital Surface Models (DSMs).

Why Use a LiDAR Drone?

Highly Accurate

LiDAR drones can produce centimeter-level accuracy, making them ideal for topographic surveys, construction planning, and engineering projects.

Vegetation Penetration

Unlike cameras, LiDAR lasers can penetrate vegetation, allowing you to see the ground beneath trees and brush — crucial for forestry, archaeology, and environmental monitoring.

Faster Data Collection

Drone-based LiDAR surveys can cover large areas quickly — reducing time, labor, and cost compared to ground-based methods.

Safe and Remote Access

LiDAR drones can access steep, dangerous, or remote areas, reducing risk for field crews.

Think About It:
If LiDAR can “see through” foliage, where else could it be useful?

🌳 Forestry

🏗 Construction sites

🏛 Archaeology

Real-World Applications

Construction & Engineering
No more guesswork! LiDAR drones create ultra-precise 3D models of construction sites.
Cut costs by tracking stockpile volumes automatically.
Smart Farming
Monitor crop health by scanning fields in minutes.
Optimize irrigation with detailed elevation maps.
Mining & Quarries
Measure stockpiles without climbing dangerous piles.
Detect slope instability before collapses happen.
Forestry & Environment
Count trees and estimate timber volume.
Track deforestation with millimeter-level accuracy.

Did You Know?
LiDAR helped discover lost Mayan cities hidden under thick jungle!

Challenges & Limitations

High Initial Costs: Professional LiDAR drones cost $20,000–$100,000+.
Data Processing Complexity: Requires specialized software & expertise.
Regulatory Restrictions: Airspace regulations limit drone operations in urban areas.
Battery Life Constraints: Most drones have 20–40 min flight times, requiring multiple sorties.

LiDAR-equipped drones are transforming surveying by providing fast, accurate, and cost-effective geospatial data. Whether for construction, agriculture, mining, or urban planning, this technology enhances efficiency and decision-making.

This brings us to the end of the blog. I hope this article gained some knowledge for you!

Thank you for reading.

About SurveyGyaan

SurveyGyaan is an educational initiative under the Surveyaan brand, which is a subsidiary of Nibrus Technologies Private Limited. Surveypod specializes in DGNSS/DGPS manufacturing in INDIA.

Surveypod: www.surveypod.in

Surveyaan: www.surveyaan.com

How DGNSS and Drone Surveying are Revolutionizing Land Surveying and Mining Industry

Wed, 02 Jul 2025 10:44:52 +0000

When it comes to land surveying, accuracy and efficiency aren’t just nice to have — they’re everything. Whether you’re building roads, planning a mining site, or laying railway tracks, precision in your data collection is what lays the foundation for success. Enter DGNSS (Differential Global Navigation Satellite System) and drone-based surveying — two technologies that are transforming how surveyors and civil engineers work on the ground.

In this blog, we’ll break down what DGNSS and drone surveying are, how they work together, and why industries like mining, construction, road and railway departments are shifting to these modern tools.

What is DGNSS & Why Does It Matter for Drone Surveys?

DGNSS = Differential GNSS (Global Navigation Satellite System)

Unlike standard GPS (which can have 5–10m errors), DGNSS corrects satellite signals using:
A base station (on a known coordinate)
A rover (drone/RTK receiver)
This brings accuracy down to 1–2 cm — critical for engineering-grade surveys.

Two Flavors of DGNSS:

RTK (Real-Time Kinematic) — Corrections sent live to the drone (best for real-time mapping).

PPK (Post-Processed Kinematic) — Data corrected later using software (more reliable in areas with poor connectivity).

Fun Fact: Our SurveyPod DGNSS supports both RTK & PPK, so you’re covered in any terrain.

What is Drone Surveying?

Drone surveying uses UAVs (Unmanned Aerial Vehicles) equipped with high-resolution cameras or LiDAR sensors to capture aerial data over large areas. Instead of spending days walking the terrain with a total station, drones can cover 60 hectares in one flight — in just minutes.

Why Drones Make Sense:

Speed: Quick data capture means faster project planning.
Safety: No need to send people into dangerous or inaccessible areas.
Coverage: Large areas can be surveyed in a single flight.
Accuracy: With GNSS correction, drone data is incredibly precise.

Fun Fact: Our Surveyaan V1 drone is a compact, sub-2kg UAV perfect for this.

How DGNSS and Drone Surveying Work Together

Here’s where it gets interesting. Drone surveying becomes exponentially more powerful when paired with DGNSS. With a GNSS base station providing corrections, you can geo-tag aerial images with high-accuracy coordinates, enabling:

Accurate orthomosaic/orthophotos, dsm/dtm, point clouds
Precise 3D and 2D models
Reliable contour and elevation data

For instance, in a road widening project, you could:

Use Surveyaan V1/Surveyaan V1+ to capture the entire stretch of land.
Use Surveypod DGNSS to place accurate Ground Control Points (GCPs).
Process everything in a cloud photogrammetry tool like Surveyaan Geoworkspace for instant outputs.

Who’s Using This Technology?

Industries already adopting UAVs + DGNSS surveys include:

Civil engineers & Surveyors: For land survey, topographic surveys, aerial maps and more.
Mining departments: For volume calculations, pit mapping, and safety monitoring.
Highway & Road departments: For route alignment, site inspection, and project monitoring.
Railway departments: For corridor mapping and encroachment analysis.
Infrastructure companies: For project planning, reporting, and audit documentation.

In a world where projects are bigger, timelines are tighter, and accuracy is non-negotiable, DGNSS and Drone surveying are not just buzzwords — they’re becoming the new standard. Whether you’re surveying a quarry, planning a bridge, or laying down a new railway line, combining these two technologies can save time, cut costs, and boost reliability

If you’re curious to explore how modern tools can help your team, check out our Surveypod DGNSS receiver and Surveyaan V1 drone — designed and built for real-world survey professionals like you.

Longitudinal and Cross Sectioning

Mon, 08 Jan 2024 11:12:55 +0000

Surveying is a crucial aspect of civil engineering and construction projects, providing accurate measurements and data for planning, design, and implementation. Two important techniques used in surveying are Longitudinal and Cross sectioning. These methods allow surveyors to gather detailed information about the terrain, enabling engineers to make informed decisions during the construction process.

In this blog post, we will explore the concepts of Longitudinal and Cross sectioning, their applications, and the benefits they offer in surveying.

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.

The process of creating a longitudinal section typically involves the following steps:

Establishing a base line: A straight line is marked along the path of the feature being surveyed. This line serves as the reference for all subsequent measurements.

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.

The process of creating a cross section typically involves the following steps:

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.

Benefits of Cloud-based Photogrammetry Software

Mon, 08 Jan 2024 11:12:55 +0000

Photogrammetry is the technology of creating 3D models, orthomosaics, point clouds, or other geospatial data from a series of overlapping photographs or images. With photogrammetry, you can measure and model the real world with a camera. Photogrammetry is used in the military, construction, land surveying, real estate, etc.

Photogrammetry extracts geometric information from a two-dimensional image. You can create a three-dimensional image by combining several images. Photogrammetry is the process of creating a 3D scan of an object by combining multiple images. It is possible to create a 3D model of an object by taking several pictures of the object from various angles to obtain a complete representation of the object. With the help of a simple smartphone, tablet, or camera, you can capture photos.

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.

IBM Drone Survey SOP March 2023 Updated

Mon, 08 Jan 2024 07:01:45 +0000

The Government has updated the Standard Operating Procedures (SOP) for drone surveys and submission of Digital Aerial Images of Mining areas to the Indian Bureau of Mines. Let’s see what has been updated under the new SOP.

IBM has updated the Ground Control Points. With a certified DGPS instrument, the mine should establish at least 5 GCP per sq km of the lease area. An example is also provided to aid comprehension. If the leased area is 478 ha, a minimum of 24 GCPs, including three permanent GCPs, should be placed within the leased area.

The updated SOP has also given more comprehension of the leased area covered with thick canopies. It is not possible to place GCPs in areas filled with dense canopies within the leased area. In such leased areas with dense canopy parts, GCPs can be reduced proportionally and distributed well in the remaining parts of the leased area. E.g., If 200 ha of the 478 ha lease area is covered with a thick canopy, then 14 GCPs, including three permanent GCPs, must be established in the remaining 278 ha.

The figure above shows a leased boundary containing part of a canopy. It is not possible to place GCPs in areas filled with dense canopies. So here, the GCPs are distributed well in the remaining parts of the leased boundary.

The data outputs needed to be provided to IBM by the lessee have also been updated. The updated data outputs are discussed one below the other.

The Orthomosaic image should include a buffer zone of 100m, and it should be a single image.The spatia resolution of the image has also been defined, which should be less than or equal to 5 cm in UTM Projected Coordinate System and in Geotiff format.

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.

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.
The Permanent GCP data needs to be submitted to IBM both in GCS WGS-84 datum, and UTM Projected Coordinate System in Excel Format.
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. ML Boundary
2. Topsoil stack
3. Infrastructure
4. Roads
5. Railways
6. Tailing Pond
7. Effluent Treatment Plant
8. Mineral Separation Plant
9. Township Area
10. Others to specify (Green Belt area)

The data should be submitted in the UTM Projected Coordinate System in the shapefile format in polygon geometry along with the associated files. The above-mentioned applicable land use data needs to be provided in a single shape file with proper nomenclature of features in the attribute data of the shape file.

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.

As per the updated SOP, the processed output data must also be submitted to the State Governments. It had to be submitted to the Chief Mining Geologist and the Respective Regional Offices of IBM earlier.

IBM Drone Survey SOP — Output Data Submission

Mon, 08 Jan 2024 06:29:59 +0000

Standard Operating Procedure (SOP) addresses guidelines for the drone pilot to follow during flight, pre-flight and post-flight procedures to ensure the highest degree of safety. Each lessee must provide IBM with the data output for the previous financial year.

10. Data Output and Formats

The outputs that need to be submitted are discussed below:

Orthomosaic

Orthomosaic is a large, high-resolution map-quality image that combines many smaller images called orthophotos. Submitting the orthomosaic image of the leased boundary to IBM is mandatory. As a reminder, the orthomosaic of the leased boundary should also incorporate a 100m buffer zone. The buffer zone is included to monitor the environmental impact and ascertain any excavation therein. The data should be submitted in a GEOTIFF format.

The figure above shows the Orthomosaic map in Geotiff format.

Make sure the Ground Sample Distance (GSD) is less than 5 cm per pixel or 5cm per pixel.

GSD is the distance between the centers of two successive pixels on your map, measured in inches, centimeters, or millimeters. A drone can measure with a GSD of 5 cm/px, meaning that each pixel on your digital map represents 5 centimeters of actual space in the real world.

Digital Elevation Model (3D) — DSM & DTM

The Digital Elevation Model is a 3D representation of the terrain elevations on the earth’s surface.

The Digital Terrain Model is a subset of DEM and consists of the earth’s surface and excludes buildings, trees, etc.

The Digital Surface Model is a subset of DEM and consists of the earth’s surface, including all objects like buildings, trees, etc.

While submitting to IBM, ensure the DSM and DTM are in GeoTif format.

The Figure above shows the Digital Surface Model and Digital Terrain Model in GeoTif format.

The resolution of the Digital Elevation Model (DEM) should be 15 cm per pixel or better.

Ground Control Points

Ground Control Points (GCPs) are the points on the earth’s surface that help georeference raster data such as satellite, aerial, or drone imagery. The GCP data should be submitted to IBM in shapefile and Excel format.

The figure above is an Orthomosaic image in GeoTif format. The red points are the Ground Control Points overlaid on the orthomosaic file in shapefile (SHP) format.

The figure above shows the GCP data in Comma Separated Value (CSV) format.

RMSE Report

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. With the help of any Photogrammetry Software, we can get a detailed GCP report. I have generated the report using Surveyaan Geoworkspace. The RMSE report should be submitted to IBM either in .txt or in .doc format.

From the figure above, we can view the GCP report in .doc format.

Map

The lessee should submit the map of the mining lease to IBM showing area of;

a) actual excavation (mineral and waste)

b) Mineral storage

c) Subgrade dump

d) Waste dump

e) Afforestation

f) Backfilled, reclaimed, and rehabilitated area

within the lease for the preceding financial year. The data should be submitted in the UTM Projected Coordinate system in shp format.

In the figure above, the black shape shows the waste dump, and the blue shape shows the reclaimed area. Both are in Shapefile (shp) format and in UTM Projected Coordinate System.

In the figure above, the area is calculated from the Surveyaan Geoworkspace using the Area tool in the Measurement Tools. The measurements are then saved with a suitable name. The shapefiles are then generated then using the DXF SHP export button.

Boundary Pillar

It helps in identifying the mining boundary and also helps to prevent encroachment. Unique identification numbers also mark the pillars. With the help of the DGPS, the coordinates of the pillars are noted. The Boundary pillar data should be submitted to IBM in shapefile (shp) and Excel.

In the figure above, the red points show the boundary pillars’ position. Here the points are in shapefile (shp) format and are in UTM Projected Coordinate System.

In the figure above, the red points show the boundary pillars’ position. Here the points are in shapefile (shp) format and are in Geographic Coordinate System.

Drone Survey Log Sheet

The drone survey log sheet consists of general checking fields like the airspace map, wind speed, cloudiness etc. It also contains the flight log where information on each flight including the date, place and time of operation are recorded. The drone survey log sheet should be submitted to IBM in .doc format.

The figure above, is kind of a General Log Sheet and IBM has not defined any standard format for it.

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

You can edit text on your website by double clicking on a text box on your website. Alternatively, when you select a text box a settings menu will appear. your website by double clicking on a text box on your website. Alternatively, when you select a text box

IBM Drone Survey SOP - Rules for carrying out Drone Survey

Sat, 06 Jan 2024 13:44:06 +0000

The Government released several sets of instructions to allow the operation of UAV drones called the Standard Operating Procedures (SOP) for carrying out drone survey and submission of Digital Aerial Images of Mining areas to 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.

Standard Operating Procedures for carrying out drone survey and submission of Digital Aerial Images of Mining areas to Indian Bureau of Mines

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.

Red zones are highly restricted zones and can be operated only after permission from the authorities.

From Airspace Map of India above, In the Airport Yellow [8-12 km] zone , drones can be operated only upto 60m. In the Airport Yellow [5-8 km] zone and Airport Red zone , drones can be operated only after permission from DGCA.

From the figure as shown above, we can see that this is the International Boundary. This is a highly restricted zone.

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

The drone should have a minimum 20 megapixel or higher resolution RGB camera with the capability to capture high-quality undistorted pictures. Camera should have the resolution to capture the images less than 5 cm Ground Sample Distance or 5 cm per pixel. The resolution of Digital Elevation Model should be 15 cm/pixel.

4. Drone flying path and flying height

The path plan should be such that there is enough overlap between the photos. The front overlap should be minimum 80% and side overlap should be minimum 70%. The flight altitude should be as per DGCA prescribed limits. The camera angle should be kept at 90° vertically downwards.

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.

6. Ground Control Point for Drone Surveys

Each mine must establish at least 5 GCPs per sq. km of lease area with a certified DGPS instrument before undertaking the drone survey. If area is less than 1 sq.km, 4 GCPs are only needed.

Points to Note while placing GCPs:

GCP must be easily visible.
It should be well distributed all over the area.
Dimensions: Minimum 50cm by 50cm and mark X with contrast colors
Increase the size of the GCP depending at which height you fly.
The Root Mean Square (RMS) Error should be less than 5cm.
At least 3 GCPs must be placed permanently at undisturbed locations and has to be covered in subsequent surveys to cross check the error.
Boundary pillars shouldn’t be considered as permanent GCPs.

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.

8. Co-ordinate Reference System

The Co-ordinate Reference System of the photos captured and used in drone survey should be in (Latitude, Longitude) with WGS84 Datum and Decimal Degrees/Degree Minute Seconds as unit.

To find the coordinates of the photo used in the drone survey, right click on the image and got to Properties and then switch to the Details tab and scroll down to the GPS section.

From the Figure above, these are the photos captured by the drone and here you can see that the (Latitude, Longitude) values are in Degree Minute Second (DMS).

The Orthomosaic shall be submitted in the Universal Transverse Mercator (UTM) and unit as meters.

From Figure above, this is an orthomosaic file and here it is in UTM Coordinate Reference System having EPSG Code: 32643 and the coordinate values are in meters.

The GCPs survey data and boundary pillar coordinates shall be submitted in (Latitude, Longitude) with WGS84 Datum and Degree Minute Seconds as unit.

The precision of the data submitted in (Latitude, Longitude) with WGS84 Datum should be in format as (DD MM SS.SSSSSS)

From Figure above, it shows the properties of an image used in drone survey. Here the (Latitude, Longitude) values are in Degree Minute Second (DMS) and in the seconds value you need to have precision upto 6 digits.

9. Preservation of Raw and Processed Data

The raw and processed data of each survey must be kept safely with the lessee for a minimum period of five years. The data must be submitted to IBM in case required by IBM for verification at any stage. The data can be stored in cloud platforms such as Surveyaan Geoworkspace, so that there is no risk of getting the data lost or corrupted.

Now, we will continue in the next blog mentioning about the data outputs and formats needed to be submitted to IBM.

Drone Survey of Large Sites

Thu, 21 Dec 2023 14:27:37 +0000

Surveying large areas present significant challenges in terms of battery life, overlap, covering all areas, drone range, and safety. Most of the difficulties can be dodged by careful and intelligent planning. The amount of time and money invested in mapping is directly proportional to the area to be mapped.

Pre Site Planning

KML Creation: Create a KML of the site you want to map. Make the site’s boundary large enough, so you don’t miss any area you plan to map. With the help of earth browsers such as Google Earth, you can study the area you want to map by inspecting the area. Make sure to confirm that no structures such as chimneys, tall trees, buildings, or any other construction hinders the drone’s path. If any construction or facility that may threaten the drone is inside the boundary of your site, plan in a way that you fly above it.

Splitting the KML: If the area is large enough and has varied landscapes on your site, you need to break the KML. Split the KML according to your requirement and give a unique identification to the KMLs created. While splitting the KML, make sure to have overlapping between adjacent KMLS. Also, you can find a safe and clear elevated area as your home position (Drone Take-Off Position). Make sure the home position is accessible by road and is open and clear. Save the location of the home position while planning.

E.g., From Figure above, we can see that this is a mining terrain with a boundary of 310 hectares. The maximum elevation on the left part of the site is 365m, and the maximum elevation on the right part is 480m.

We need to split the KML into two parts since there is an elevation difference of more than 110m. We have saved the KML to Boundary A and Boundary B. Boundary A and B have areas of 144 and 166 hectares, respectively. 30m Overlapping is ensured between the adjacent KMLs denoted by the red line. The home position is represented by the yellow pinpoints and is saved as Home 1 and Home 2, respectively. The home position of Boundary A can be set at any safe and clear point whose elevation is above 345m. The home position for Boundary B can be selected at any safe point whose elevation is above 460m. Here the home positions are set at 354m and 465m, respectively.

While marking the home position, ensure the boundary is within the drone range. The drone range varies with different drones. We can find the distance from the home position using the Measure Distance and Area option from Google Earth. Measure and check if the boundary exceeds the drone range. Change the home position if the boundary exceeds the drone range.

GCPs can also be placed in each KML. Generally, per sq. km or 100 Hectares, 4–5 GCPs are more than sufficient to geo-reference raster data. The thumb rule of placing the GCP is that wherever there’s an abrupt change in the terrain, you can set the GCP, and also, GCPs should be spread out uniformly throughout the landscape. Since the boundary A and B have an area of more than 100 hectares, we can place 6 GCPs per KML.

On Site operations

Planning just the KML is not enough. We must also be aware of other parameters significantly affecting the results while mapping large areas.

Setting the Overlap: Each drone has a different field of view (F.O.V.) based on the camera. This has consequences for mission planning, particularly for mapping missions that cover large areas. Overlap matches the features between photographs. There are two types of overlap:

Front Overlap: The overlap between successive photographs on a flight path is called front overlap. Increasing the front overlap makes the camera capture more photos quickly. It only affects the number of images.

Side Overlap: The overlap between photographs in adjacent parallel flight paths is called the side overlap. Increasing the side overlap gives more matched features in the imagery but reduces the area your drone can cover in one flight. The flight duration also increases as the number of lines increases.

Increasing the overlap for a flight creates more matched points and greater accuracy. Lower altitude and higher overlapping will increase the number of images and the time required for the flight, but worth it in the long run, as this helps obtain high-resolution images.

Altitude and GSD: It may also come as no shock that flying the drone at a higher altitude helps the camera cover more land area in a single image with fewer batteries and less time overall. This interprets more enormous possibilities for capturing distinctive features in multiple images. But the reciprocation is that the image’s resolution and accuracy will be compromised. Flying at low altitudes captures more details of the area. It also helps match common points while processing, increasing the image resolution and accuracy.

The formula to calculate GSD is (flight altitude X sensor height) / (focal length X image height and width).
Low altitude and high-resolution sensors will give low GSD. Lower GSD results in higher accuracy.

Battery: The optimization of your battery life will differ depending on the type of drone you use. Mapping large areas require more than one battery to map the whole area. Make sure to carry extra batteries and plan efficiently to save battery life. If the site is large, then you need to make battery swaps. The drone returns home when the battery gets low, and you need to swap the battery and resume the mission. The drone then flies to the position from which it triggers a return home and continues the mission. Store your batteries in a place with stable temperatures.

Environmental factors: Plan and keep an extra day mapping large areas due to environmental factors such as precipitation, wind, etc. It is wise to avoid flying your drone at high wind speeds. You can estimate the wind using wind apps. My personal favorite is windfinder.com. This app has detailed wind forecasts and weather forecasts that let you always find the spot with the best wind weather conditions. Every drone pilot needs to have this app because it will help you plan your flight well.

Check Data in the Field: Technical errors, like camera glitches, overexposed photos, etc., may arise while you are on the field. It is always recommended to review the data you have collected while you are still on-site to make any necessary corrections. The Map Viewer tool from this website solved my problem of checking data in the field. This free tool allows you to upload images, GCP, and KML. The user can then verify that all the images taken are within the KML border by viewing the photos and flight path on a base map.

Guidelines for Automated Drone Mapping Part 1

Thu, 14 Dec 2023 13:40:30 +0000

Drones have come a long way in the survey and construction sectors, and their capabilities have greatly improved over time, making UAVs the surveyors’ best friend. Before diving into how to fly the drone, let’s ensure we understand the practice.

The automated drones are controlled using Ground Control Software (GCS). Ground Control Software is a tool for the user to control the drone. One should follow these steps for an efficient drone survey.

The initial phase for Drone Mapping is it’s Planning.

Planning

Planning is the most important step of the drone mapping. If done properly, flying drone on the field is a cakewalk. One of the better ways to plan a survey site is by creating KMLs beforehand. KML files store geographic data and are a great way to define flight area boundaries in Google Earth. Users can import the KML file as a polyline or polygon. Polylines can represent the line features and can be used for corridor mapping. Polygons can be used for general land surveys and to describe other polygon features.

Locate Your Site

Follow these steps before going to the field.

Use Google Earth to get an idea of the survey site.
Try to create a KML file of the site from the office itself. This will help the user to spend less time on the site and be more aware of the site.
Prepare the GCP points before going to the field.

Setting up GCP Points

Ground control points (GCPs) are places on the ground with precisely known locations. GCPs are primarily used in projects that exclusively demand precision mapping, like construction, mining, topographic surveying, etc. You should use ground control points if your project requires high global accuracy. GCP points are measured through DGPS.

Generally, per sq km or 100 Hectares, 4–5 GCPs are more than sufficient to geo-reference raster data.

The thumb rule of placing the GCP is that wherever there’s an abrupt change in the terrain, you can place the GCP, and also, GCPs should be spread out uniformly throughout the terrain.

Obtaining high-accuracy survey-grade coordinates for your GCPs is critical.

Alternative to GCP

To improve the accuracy of the GNSS data, there are two techniques:

Real-Time Kinematic (RTK) is a GPS correction technology that provides real-time location data corrections when the survey drone captures site photos. Ground control points are unnecessary if you use an R.T.K. drone.

Above Figure shows the Real Time Kinetic (RTK) method. In this method, the satellites are communicating with the GNSS base station and the drone which acts as a rover. The GNSS base station communicates with the drone base and from the drone base station correction signals are sent to the drone.

Post Processed Kinematic (PPK) is another GPS correction technique that corrects location data after the drone data has been captured and uploaded.

Figure 5 shows the Post Processed Kinematic (PPK) method. In this method, there is no communication between the GNSS base station and the drone.

Factors to keep in Mind when it comes to Accuracy

The quality of the GCPs, Low image resolution, and lousy lighting contribute to loss of accuracy. If the GCPs are not appropriately marked, it can affect the positional accuracy. Drones flying at high altitudes with improper overlap can result in low resolution and accuracy errors. Plan the mission when there is adequate sunlight. Less or more sunlight can tamper with the results.

Camera Requirements

Resolution
The drone should have a higher resolution RGB camera with the capability to capture high-quality undistorted pictures. The more the resolution, the better the quality of the images.

ISO
ISO is the camera sensor’s sensitivity to light. A lower ISO value means less sensitivity to light, while a higher ISO is more sensitive. 400 ISO and below will provide good images.

Shutter Speed
It’s the speed at which the shutter of the camera closes. Shutter speeds between 1/240 and 1/1,200 should provide images without motion blur.

Drone Controls

Now, that you understand about camera, accuracy, GCPs, we can discuss a bit about the drone controls.
Pre-Checks: Before each flight, it is mandatory to arm the drone to check whether the propellers are correctly locked. Make sure all the sensors are calibrated properly.
Return To Home: The return to home option is to call the drone back to its home in case of emergencies while flying a mission.
Land: It is used to land the drone at its current position. The drone will land at the position where the option was triggered by keeping the position locked and will land on the ground.

Last but not least, we will discuss the altitude at which the drone should be flown and how forward and side overlap affects the quality of the map.
Altitude: It may also come as no shock that flying the drone at a higher altitude helps the camera cover more land area in a single image with fewer batteries and less time overall. This interprets more enormous possibilities for capturing distinctive features in multiple images. But the reciprocation is that the image’s resolution and accuracy will be compromised. Flying at low altitudes captures more details of the area. It also helps match common points while processing, increasing the image resolution and accuracy.
Overlap: Each drone has a different field of view (FOV) based on the camera. This has consequences for mission planning, particularly for mapping missions that use overlap to determine flight paths.

Overlap matches the features between photographs. There are two types of overlap:

Front Overlap: The overlap between successive photographs on a flight path is called front overlap. Increasing the front overlap makes the camera capture more photos quickly. It only affects the number of images.

Side Overlap: The overlap between photographs in adjacent parallel flight paths is called the side overlap. Increasing the side overlap gives more matched features in the imagery but reduces the area your drone can cover in one flight. The flight duration also increases as the number of lines increases.

Now, we will continue in the next blog mentioning about some interesting facts related to Drone Mapping.

To be continued…

Raster Data in GIS

Tue, 12 Dec 2023 13:42:00 +0000

The spatial characteristics of features can be stored in GIS in one of 2 ways: Vector data or Raster data.

Vector is a data structure that can be used to store spatial data. It is used to represent real-world features and assign attributes to those features. Vector data comprises of individual points, stored as coordinate pairs that indicate a physical location in the world. Data in this format can have a geometry type of point, line, and polygon.

Difference between Raster Data and Vector Data

Raster data is made up of pixels (also referred to as grid cells). Each pixel is associated with a specific geographical location. Raster data is an abstraction of the real world. It is used in Aerial imagery, satellite images, and shaded relief raster’s as the base layer when making maps to provide more meaning to the vector information.

Continuous and Discrete Raster Data

Continuous data has no clearly defined boundaries. Some continuous data examples are temperature, rainfall, and elevation measurements.

Discrete data is geographic data that only occurs in specific locations and can exist independently.

Advantages of Raster Data

Data structure: It has a simple matrix of cells with values representing a coordinate.
Simulation: It is easy because cells have the same size and shape.
Performance: It has a good ability to represent continuous features and perform surface analysis.
Compatibility: Compatible with remote sensing images and aerial images.
Cost: The application software is cheaper.

Disadvantages of Raster Data

Representation: It is hard to represent objects less than cell size.
Spatial Resolution: Finer resolution generates vast amounts of data.
Size: Datasets are enormous.
Topology: It is challenging to represent topological connections.
Accuracy: Precise locations may not be recorded as accurately as Vector data.

Raster Data Formats

Each raster format represents a different way of storing geospatial data on a computer. Each data format is more or less suited to specific types of projects.

Portable Network Graphics (PNG): It is a raster file format that allows lossless Compression. Lossless compression reduces file size without decreasing image quality. They are designed for efficient viewing in web-based browsers such as Internet Explorer, Firefox, and Chrome.

JPEG (Joint Photographic Experts Group): It is a commonly used method of lossy compression for photographic images. In lossy compression, the data in a file is removed and not restored to its original form after decompression. This data loss is not usually noticeable to the naked eye.

Tag Image File Format (TIFF): A computer file that stores raster graphics and image information. They hold high-quality images and have either a .tiff or .tif extension. They are a lossless form of file compression.

In Figure above, the Orthomosaic map is in TIFF format and can be opened in any GIS software. These files contain a .tif extension.

GRID: It is a raster GIS file format developed by Esri. It has a proprietary binary format and a non-proprietary ASCII format. The binary format is widely used within Esri software, such as ArcGIS. In contrast, the ASCII format is used as an exchange, or export format, due to the simple and portable ASCII file structure.

IMG: It is a proprietary, partially documented format for multi-layer geo-referenced raster images developed originally for use with ERDAS IMAGINE software. This format is used widely for processing remote sensing data since it provides a framework for integrating sensor data and imagery from many sources.

USGS Digital Elevation Model (DEM): It is a popular file format due to widespread availability, the simplicity of the model, and the extensive software support for the format. Each pixel value in these grid-based DEMs denotes spot elevations on the ground, usually in feet or meters. In their native format, they are written as ANSI-standard ASCII characters in fixed-block format.

In Figure above, the Digital Surface Model map can be opened in any GIS software. The Digital Surface Model is a subset of DEM and consists of the earth’s surface, including all objects like buildings, trees, etc.

This brings us to the end of the blog. Hope this article gained some knowledge for you!