Here’s a simplified workflow:

1. Data Capture: The drone autonomously flies and captures hundreds (or thousands) of geotagged images.
2. Photogrammetry Processing: Images are uploaded to photogrammetry software like GeoWorkspace or other photogrammetry software
3. 3D Model Generation: The software uses algorithms to create a point cloud, which is then converted into a textured 3D mesh model, Digital Surface Model (DSM), and orthomosaic maps.

Why Use Drones for Surveying & 3D Modeling?

Drones provide:

    High Accuracy — Sub-centimeter precision with RTK/PPK-enabled drones.

    Time & Cost Savings — Rapid data collection compared to ground surveys.

    Detailed 3D Models — Generate orthomosaics, point clouds, and digital elevation models (DEMs).

    Improved Safety — Access hard-to-reach or hazardous areas without risk.

Top Photogrammetry Software for 3D Modeling

To turn drone-captured images into 3D models, you need powerful photogrammetry software.

Surveyaan Geoworkspace: Cloud-based processing with easy sharing.

Surveyaan V1: Survey drone designed specifically for surveying, mapping, and 3D modeling

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!

1. 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.

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

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.

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.

Thank you for reading.

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 DGNSS Tilt Compensation?

By integrating an IMU, GNSS receivers gain inertial data, which helps:

1. Bridge signal gaps when satellites are temporarily lost
2. Maintain positioning accuracy during high dynamic motion
3. Provide smooth and continuous data streams even in GNSS-denied environments

Figure 1: Drone Categories in India

Figure 2: Drone with UIN Number

• Micro, Small, and Medium Drones (>250g to ≤150kg): UIN is mandatory.
• Imported Drones or those without Type Certification cannot get a UIN and are not allowed to operate.

Why is UIN Important?

Step-by-Step Process to Register Your Drone

Figure 3: Registering drone through DGCA website

1. 1. 1. Obtain a Digital Sky Account

   • Visit the official portal: https://digitalsky.dgca.gov.in
   • Register as an operator (Individual or Organization).

           2. Apply for a Unique Identification Number (UIN)

   There are 2 ways to generate UIN Number.

   Apply UIN for cases exempted from Type Certificate (Model or a Nano UAS)

   • Organisations can create manufacturer account and profile on DigitalSky platform, if not already created.
   • Login to DigitalSky platform and Select ‘Add Exempted Model’ menu option from the dashboard
   • Fill all mandatory details of your Exempted UAS model and add your model on Digital Sky Platform
   • Once model is added, Individual/Organisation user can Add UAS Serial Number from dashboard, for the added UAS Model.
   • User can Click Apply for UIN for the added UAS serial number
   • Preview the Application for Registration of UIN, Pay ₹100 fee and Submit Form D-2 (Application for Unique Identification Number) Upon successful receipt of requisite fee, the UIN will be generated.

1. Apply for UAS which is Type Certified model

   • Create your account and profile on Digital Sky platform, if not already created.
   • Login to Digital Sky platform and add your UAS Serial Number from dashboard.
   • Navigate to the list of UAS and Apply for UIN for the added UAS serial number
   • Preview the Application for Registration of UIN (Unique Identification Number)
   • Pay ₹100 fee and complete the submission of Form D-2 (Application for Unique Identification Number)
   • Upon successful receipt of requisite fee, the UIN will be generated.

Figure 4: Using a drone without UIN (when it’s legally required)

Figure 5: UIN under DGCA

Picture 1: DGNSS set to Static Mode

Figure 2: The rover is getting real time corrected data from base

Figure 3: The rover is getting real time corrected data from base

You may have heard people emphasize the importance of having 400, 800, or even 1200 channels in a DGNSS receiver. Have you ever thought deeper to understand what this actually means? Let’s clarify this with some simple mathematical calculations.

Real Time Kinematics

Pros of Real Time Kinematics

• Accuracy: RTK GNSS offers centimeter-level precision, making it ideal for applications requiring accurate location, such as surveying, construction, and agriculture.
• Real-Time Corrections: RTK applies corrections to the GNSS signal in real time, allowing users to acquire precise location data in a fraction of seconds. This capability is especially useful for applications requiring fast input or change, such as machine control in construction.
• Increased Efficiency: RTK technology allows for quicker data collecting and decision-making processes, which improves efficiency in a variety of applications. Surveyors, for example, may conduct fieldwork more rapidly with RTK, resulting in shorter project schedules.
• Versatility: RTK GNSS may be used in a wide range of settings and situations, from metropolitan regions with tall structures to broad open fields. Its adaptability makes it appropriate.

Cons of Real Time Kinematics

• Line-of-Sight Requirements: RTK GNSS requires a clear line of sight between the receiver and the satellites. Signal barriers, such as buildings, trees, or topography, might reduce performance and accuracy.
• Reliance on Base Station: RTK systems rely on a nearby base station to send correction data to the rover receiver. This reliance restricts the range of operation and may be impractical in distant or inaccessible places without a network of base stations.
• Vulnerability to Signal Interference: RTK GNSS signals are vulnerable to interference from sources such as electromagnetic interference (EMI), multipath reflections, and atmospheric conditions. Interference can impair signal reception and reduce accuracy, particularly in urban or industrial settings.
• Infrastructure costs: Setting up and maintaining RTK infrastructure, including base stations and communication networks, may be expensive, especially for large-scale projects or businesses with several locations. Furthermore, continuous subscription costs for correction services may increase the overall cost of RTK GNSS use.

Post Processing Kinematics

PPK is an alternative to RTK that applies positional corrections retrospectively. This means that in PPK mode, the GNSS rover and GNSS base station do not need to be connected when functioning. You simply need to record raw GNSS data (logs), which are subsequently processed to produce accurate positioning data that may be utilized for computations in postprocessing.

Post-Processing Kinematic (PPK) GNSS technology offers unique advantages.

Pros of Post Processing Kinematics

• High Accuracy:Similar to RTK, PPK GNSS provides centimeter-level accuracy, ensuring precise positioning data for various applications such as surveying, mapping, and asset management.
  
• Flexibility in Data Collection:PPK technology allows users to collect GNSS data without the need for a real-time correction source or continuous communication with a base station. This flexibility is advantageous in remote or challenging environments where real-time corrections may not be available.
  
• Cost savings: With PPK GNSS, there are no continuing subscription fees or infrastructure expenditures connected with real-time correction services. This can result in cost savings over time, particularly for firms that do regular or large-scale GNSS surveys.
  

Cons of Post Processing Kinematics

• Delayed Results:Unlike RTK, which gives real-time positioning data, PPK GNSS requires gathered data to be post-processed in order to make corrections and obtain precise results. Depending on the processing procedure and software utilized, this could cause delays in receiving final positioning data.
• Post-processing Complexity: To use PPK GNSS, users must acquire raw GNSS data in the field and process it using specific software or algorithms. This procedure can be difficult and may necessitate training or experience to provide correct findings.
• Limited Real-Time Feedback:Without real-time corrections, users cannot discover and correct positional errors or anomalies during data gathering with PPK GNSS. Additional field checks or validation procedures may be required to verify data quality before results are finalized.
  

RTK and PPK GNSS technologies have transformed the landscape of precise positioning, enabling a wide range of industries to achieve unprecedented levels of accuracy in their location-based applications. As advancements in GNSS technology continue, the future holds even greater promise for enhanced accuracy and efficiency across diverse industries.

Surveyaan Geoworkspace: app.surveyaan.com (Cloud Photogrammetry Software Website)

The way we monitor locations and travel on Earth has been completely transformed by global navigation satellite systems, or GNSS. These satellite constellations, which include GPS and Galileo, supply critical position data for a wide range of uses, from precise timing in financial transactions to automobile navigation systems. But in order to guarantee the highest level of location accuracy, obstacles including atmospheric delays and signal blockages must be overcome. Nowadays, the Continuous Operating Reference Station (CORS) networks positioning services are amongst the most used ones when the highest positioning accuracy is needed.

Idea behind CORS Network

In most of GNSS applications where precise positioning is required, users usually pair their GNSS instruments with other GNSS instruments, simultaneously observing one or more known position, termed as reference station, and with help of these reference stations estimated corrections to be applied over point of interest or rover position are obtained through Static GNSS Survey or Real Time-Kinematic (RTK) Survey methods.

To liberate users from setting of their own reference station each time they wish to undertake GNSS measurement, Continuously Operating Reference Stations (CORS) has been established, which are not only capable of providing Real Time Positioning Service through RTK/NRTK with an accuracy of ±3cm, but also host an array of different positioning services targeted to cater requirements for different segments of Geospatial and scientific Community.

What is CORS Network?

CORS networks are permanently installed reference stations strategically positioned across a geographic region. These stations are equipped with high-precision GPS receivers and antennas that continuously collect and process GPS data to calculate position corrections. These corrections account for various factors that can affect signal accuracy, such as ionospheric and tropospheric delays, satellite orbit errors, and multipath interference. The data is then transmitted to a central processing facility where it is used to provide real-time, accurate positioning information for a variety of applications.

Characteristics of CORS Network

CORS in INDIA

India has been actively developing and deploying its own CORS (Continuously Operating Reference Stations) network in conjunction with its regional satellite navigation system called NavIC (Navigation with Indian Constellation). NavIC, also known as the Indian Regional Navigation Satellite System (IRNSS), is a constellation of satellites developed by the Indian Space Research Organisation (ISRO) to provide accurate positioning and timing services over the Indian region and surrounding areas.

How CORS network function in India using NavIC?

• India has been establishing a network of CORS stations across the country. 
• These CORS stations are equipped with high-precision GNSS receivers and antennas, allowing them to continuously monitor signals from both the NavIC satellites and other GNSS constellations such as GPS. 
• The CORS stations collect raw GNSS measurements and transmit them to a central processing facility. At this facility, the raw data is processed using precise algorithms to compute corrections and augmentations for improving the accuracy of GNSS positioning. 
• Since NavIC is India’s regional satellite navigation system, the CORS network integrates NavIC signals into its positioning solutions. This integration enhances the accuracy and availability of positioning data, especially in areas where NavIC signals have better visibility than signals from other GNSS constellations.

The corrected GNSS data, including NavIC-based corrections, is made available to users in real-time through various means such as the internet, satellite communication, or radio links. This allows users to access accurate positioning information for their applications, including surveying, mapping, agriculture, transportation, and disaster management.

CORS Network in India — Present 

For more precise or scientific applications users can download CORS stations raw observations in non proprietary open RINEX format or virtual rinex data (i.e. RINEX files for a virtual reference station that can then be used for post processing calculations), and use it to process his own GNSS data it his own software. 

For accessing all these services users are required to get registered themselves on Survey of India CORS web site, i.e. http://www.cors.surveofindia.gov.in