Surveyaan: Drone Survey & Mapping Solutions - Blog #overlapSurveyaan: Drone Survey & Mapping Solutions - Blog #overlaphttps://www.surveyaan.com/blogs/tag/overlapThu, 12 Mar 2026 20:15:46 +0530http://zoho.com/sites/<![CDATA[How DGNSS and Drone Surveying are Revolutionizing Land Surveying and Mining Industry]]>https://www.surveyaan.com/blogs/post/How-DGNSS-and-Drone-Surveying-are-Revolutionizing-Land-Surveying-and-Mining-Industry

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:

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.

]]>Wed, 02 Jul 2025 10:44:52 +0000<![CDATA[Photogrammetry Output - Orthomosaic]]>https://www.surveyaan.com/blogs/post/photogrammetry-outputs-orthomosaicIn this blog, we’ll take a closer look at orthomosaics, how they are created, and their wide-ranging applications across diverse range of fields.]]>

From the reconstruction of ancient artifacts and archaeological sites to enhancing urban planning and disaster response, photogrammetry offers a novel approach to understanding our world.

In this blog series, we will embark on a captivating journey through the realm of photogrammetry and its outputs.

Photogrammetry is a technique used to measure and map physical objects or environments using photographs. It combines the principles of photography and geometry to create accurate 3D models or measurements from 2D images. Photogrammetry is used in the military, construction, land surveying, real estate, etc.

Through the process of photogrammetry, multiple images of an object or scene are captured from different angles or viewpoints. These images are then analyzed and matched to extract precise measurements, shapes, textures, and even colors. The software algorithms used in photogrammetry can reconstruct the 3D structure of the object based on the visual information provided by the images.

In this blog, we’ll take a closer look at orthomosaics, how they are created, and their wide-ranging applications across diverse range of fields.


Orthomosaic map is revolutionizing the field of aerial imagery and mapping applications. They are often referred to simply as orthomosaics and are created by combining remote sensing techniques with advanced photogrammetry algorithms. Orthomosaic images can be generated from overlapping aerial photographs(orthophotos). It allows us to take a bird’s-eye view of the world, capturing vast landscapes with an unprecedented level of detail and accuracy.

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.

Different Formats of Orthomosaic Map

Orthomosaic maps can be generated in various formats to cater to specific needs and applications. These formats offer different levels of detail, precision, and accessibility. Here are some common formats in which orthomosaic maps are available:

      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.

With the help of a Worldfile we can also import an orthomosaic into AUTOCAD and georeference it with the help of the GEOREFIMG AutoCAD command.

  • Worldfile: It is a six line plain text sidecar file used by geographic information systems (GIS) to georeference raster map images.
  • JPEG: JPEG is a common image format and orthomosaic maps can be saved as high-quality JPEG files. While they are more accessible for visualization, they may lack the georeferencing information that GeoTIFF provides.
  • PDF (Portable Document Format): Orthomosaic maps can be exported as PDFs for easy sharing and printing. However, like JPEG, they may not contain geospatial data.

I have used Surveyaan Geoworkspace photogrammetry software to create the orthomosaic and its formats.

The possibilities of orthomosaic mapping are limitless, and as technology continues to advance, we can expect even greater achievements and innovations.

]]>Tue, 09 Jan 2024 06:50:54 +0000<![CDATA[IBM Drone Survey SOP ]]>https://www.surveyaan.com/blogs/post/ibm-drone-survey-sopMining is the extraction of valuable minerals or other geological materials from the earth.]]>

Mining is the extraction of valuable minerals or other geological materials from the earth. The profitable substances that are mined from the earth are called minerals. The minerals are valuable in their pure form, but in earth they are mixed with unwanted rocks and minerals. This mix of mineral and rock is usually carried away from the mine and processed later and refined to isolate the mineral

The Indian Bureau of Mines (IBM) established in 1948, is a multi-disciplinary government organization under the Department of Mines. It is headquartered at Nagpur, Maharashtra. It is engaged in promotion of conservation, scientific development of mineral resources and protection of environment in mines other than coal, atomic minerals, petroleum & natural gas and minor minerals. It is primarily advisory body to help in formulation of policy and legal framework for mining sector and advising Central and State Governments on development and utilization of mineral resources.

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.

The provisions of rule 34A of MCDR are as follows:

  1. Every lessee having
    (a) an annual excavation plan of one million tonne (10 Lakh tonne) or more in a particular year, or
    (b) leased area of fifty hectare or more, The above mentioned should carry out a drone survey of the leased area. They need to survey upto 100 metres outside the lease boundary in the month of April or May every year and submit the outputs or any other format as specified by IBM on or before JULY 1st every year.
  2. Every lessee, not mentioned in the 1st rule, shall submit soft copy of high resolution Georeferenced Orthorectified Satellite images of the leased area. They need to survey upto 100 metres outside the lease boundary in the month of April to June every year and submit in GEOTIFF format along with the metadata or any other format as specified by IBM on or before JULY 1st every year. The lessee who has submitted images under the 3rd rule need not submit this result.
  3. Every Lessee, who needs to submit any mining plan document or modification to IBM need to carry out a drone survey. They need to survey upto 100 metres outside the lease boundary within six months before submission and shall submit the results along with the application for approval or modification of mining plan to the concerned Regional Controller of Mines and the Controller General, IBM.
  4. Bidders issued with a letter of intent (LOI) for grant of a mining lease shall carry out a drone survey of the mining block granted through auction. They need to survey upto 100 metres outside the lease boundary and submit the outputs along with the mining plan to the Regional Controller and the Controller General, IBM.
  5. The SOP for carrying out the drone survey and form of the data to be submitted shall be specified by IBM from time to time.

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.

From Figure above, we can see the original KML boundary is denoted by the Yellow boundary. The green boundary is the extended boundary.

Download the official SOP for UAV Survey from here.

]]>Fri, 05 Jan 2024 13:38:13 +0000<![CDATA[Guidelines for Automated Drone Mapping Part 2]]>https://www.surveyaan.com/blogs/post/guidelines-for-automated-drone-mapping-part-2We saw the initial planning phase of drone mapping in one of our previous blog. In this blog, we will discuss the Data Collection phase and how paramount it is to choose the right]]>

We saw the initial planning phase of drone mapping in one of our previous blog. In this blog, we will discuss the Data Collection phase and how paramount it is to choose the right type of mission for generating results. It is determined by the terrain and the objects to be reconstructed.

Data Collection

Drones have transformed the way we capture information. They collect massive amounts of high-quality data in real-time. Three types of missions are generally used in Drone surveys to aid the process of data collection. The user can choose a mission depending on his/her project’s requirements. Once the mission is selected, the drone flies to the initial point and takes photos regularly until it reaches the endpoint. The captured images are then processed in any photogrammetry software to obtain the results.

The common mission types used in drone surveys are:

Polygon Mission

When surveyors need to map terrain or the ground, they use the polygon mission. It is suitable for flat or bare surfaces. Users can configure flight angles, altitude, and overlap using Ground Control Software (GCS). An outline of the default mission is then displayed on a base map at the current location. The default mission shape can be modified. Once the area is marked and the angle, altitude, and overlap percentge are set, the drone will automatically fly to the initial point and begin its mission. It will return to its home position once it has reached the endpoint.

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.

Drones are a potent tool for government agencies, research scholars, and businesses. Even though modern UAVs use sophisticated technologies to reduce accidents, you should always fly cautiously. Let’s take a closer look at how to safely operate these machines in different terrains.

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.

Points to note before flying

  • Avoid heavy machinery that emits a lot of magnetic radiation.
  • Align the flight lines parallel to the pit.
  • Choose a safe elevated area as the home position.
  • Fly above the pit rather than inside it to avoid crashing.
  • Go to the mine when there is ambient sunlight. Too much or too low can tamper with the results.
  • Place GCPs in areas where the terrain abruptly changes.

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.

]]>Thu, 21 Dec 2023 13:34:14 +0000<![CDATA[Guidelines for Automated Drone Mapping Part 1]]>https://www.surveyaan.com/blogs/post/guidelines-for-automated-drone-mapping-part-1Drones have come a long way in the survey and construction sectors, and their capabilities have greatly improved]]>

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.

  1. 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.
  2. 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.
  3. 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.

  1. 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.
  2. 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.

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.

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


To be continued…

]]>Thu, 14 Dec 2023 13:40:30 +0000<![CDATA[Drone Survey & AutoCAD: Import Orthomosaic and Measurements]]>https://www.surveyaan.com/blogs/post/drone-survey-autocad-contours1Surveying is a process of determining or identifying different features of a land area. It helps in planning or mapping an area.]]>

Surveying is a process of determining or identifying different features of a land area. It helps in planning or mapping an area. Drone survey has increasingly become popular, and it is obvious so, because of its unparalleled match when it comes to accuracy, speed, cost, etc.


The workflow of drone survey is also very easy to understand. The drone flies and captures the photos of the land and returns. A user must upload photos on photogrammetry platforms likeSurveyaan Geoworkspace, etc., the software takes it’s time to stitch all photos together and then generates valuable results such as Orthomosaic, Digital Surface Model (DSM), Digital Terrain Model (DTM), 3D Point Cloud and 3D Model. These results can be imported in software like QGIS, AutoCAD.


In this article, we will learn to import Orthomosaic in AutoCAD. Before moving further, just wanted to let you guys know that the content has been posted in video format on our YouTube channel SurveGyaan by Surveyaan.


An orthomosaic, or orthophoto or orthomap, is an accurate representation of the Earth’s surface. The aerial photos are stitched together and processed to form a single map which is known as Orthomosaic. So, to import Orthomosaic into AutoCAD, we need to have one.


Import Orthomosaic

Open AutoCAD and start a new drawing. Simply drag the orthophoto into AutoCAD. It asks for few things as mentioned below:


Insertion points at origin

Fig. 1: Click anywhere on the drawing file to specify the insertion point.

Scale Factor: By default, value is 1 and we can keep the same by pressing Enter key.

Fig. 2: Press enter to keep default value (1) for scale factor.

Rotation Angle around Origin: We can keep the default value again by pressing Enter key.

Fig. 3: Press enter to keep default value (0) for rotation Angle.

Congratulations. The orthomosaic is imported.

Fig. 4

The orthomosaic imported does not contain its original world coordinates. If you type ID command, you will get X and Y coordinates of simple image relative to Origin. To display the original world coordinates, we need to install a tool named, GeoRefImg.

Install GeoRefImg Tool

Click on Add-ins (1) menu and select Exchange App Manager (2). Click on Launch the Autodesk Exchange Apps Website (3).

Fig. 5

Search for GeoRefImg tool in the search bar. To download, you need to provide credentials and then install it with the default settings.

Fig. 6

Once installed, you can verify by typing GEOEFIMG in the command or you view the same by clicking on Add-Ins again as shown below.

Fig. 7

Import World file

Make sure to have World file. Keep the file in the same location as that of Orthophoto with the same name.

Type GEOREFIMG command and select any of the corner points of the map

Fig. 8

Once selected, it highlights the map by blue and then press Enter.

Fig. 9

Calculations

Coordinates: To view the world coordinates, type again ID command and click anywhere on the map.

Fig. 10

Distance: Type DAL command and select two points to measure distance between them. The highlighted text shows the distance between two points and its unit is in meters.

Fig. 11

Perimeter and Area: Type AA command and select multiple points on the land. Once you have completed selecting the points, type T in the command box and you’ll get the Area and Perimeter as shown below.

Fig. 12
Fig. 13

Final Notes

We hope that you have learned how to import orthomosaic and perform basic measurements in AutoCAD. If there is anything that you guys would like to add to this article, feel free to leave a message! Share this if you have liked it! Thanks!

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