eBhuAdhyan - Land Survey and Management

Introduction to CORS, Its utilities & Urban Survey Methodologies

Chapters List

1: Survey of India's CORS Service 2: Field Survey Steps - An Overview

Welcome to Chapter 1 : Survey of India's CORS Service

Introduction

Survey of India (SOI) has established a Continuously Operating Reference System (CORS) across India as part of the National Geodetic Reference Frame. Currently, SOI has set up 1,034 permanent CORS reference stations and is actively working on increasing their density. Additionally, as part of the NAKSHA initiative, SOI is collaborating with the Department of Land Resources (DoLR), Government of India, to further densify the CORS network in towns and urban local bodies (ULBs).

CORS is an integrated network of permanent GNSS (Global Navigation Satellite System) base stations that deliver high-precision positioning data in real-time or post-processed modes. Each reference station is equipped with a high-precision GNSS receiver and antenna, continuously collecting satellite signals from constellations such as GPS, GLONASS, Galileo, and BeiDou. The collected data undergoes processing to generate corrections that mitigate errors caused by atmospheric interference, satellite orbit inaccuracies, and clock deviations. These corrections are then transmitted to other GNSS rover units via the internet, radio, or cellular networks. Users connect to the network through specialized software or hardware to apply these corrections, significantly enhancing their positional accuracy.

With CORS service, users can obtain high-precision positional data accurate up to 2-3 cm within a couple of minutes. Previously, for obtaining similar accuracy SOI’s Ground Control Points (GCPs), require at least 2-hour observations in the field with GNSS receivers and further post processing in the office

CORS Locations - Spatial distribution of CORS network grid (Source: cors.surveyofindia.gov.in)

CORS Introduction - In Hindi (Source: SURVEY OF INDIA CORS)

CORS Introduction - In English (Source: SURVEY OF INDIA CORS)

Key Features and Services of CORS

Datum: WGS84
High-Precision GNSS Data
Real-Time Corrections
Centimeter-level accuracy
Pan India Coverage Area

CORS station of Survey of India (Source: cors.surveyofindia.gov.in)

Services offered by SOI CORS Network

For obtaining the services of SOI CORS network, the users need to register themselves first on the CORS web portal using Registration link : CORS Registration Link and the SOP for registration can be found at CORS Registration SOP. After successful registration, users need to purchase the subscription in order to avail the services. Subscriptions are available free of charge basis to Central Govt. users, State Govt. users, and Govt. academic institutions. For rest of the categories i.e. PSU and Private users, they are required to purchase the subscription using Purchase Subscription link : CORS Subscription Link.

Real Time Positioning Services:
- Network RTK Services (NRTK):
  - This service is used to achieve the location of a point in real-time with a relative positioning accuracy of 3-4 cm.
  - To avail this service, users need to have an RTK-enabled GNSS Rover and Internet connectivity for connecting to the CORS network.
- DGNSS Services:
  - This service is used to achieve the location of a point in real-time with a relative positioning accuracy of 30-40 cm.
  - To avail this service, users need to have a DGNSS-enabled GNSS Rover and Internet connectivity for connecting to the CORS network.
Reference Data Services:
- Downloading of RAW Data of CORS Stations (RDS):
  - This service is used to download the past data of the CORS base stations themselves and to generate the Virtual observation file in Rinex format at any location within the CORS Network.
- Online Data Processing (OPS):
  - This service is used to post process the GNSS observation made on the target points in static mode. In this service, the user needs to upload the observed GNSS data to the CORS portal and in a few minutes, the user gets the precise coordinates of the point w.r.t. the CORS Network.

Source and for More Info : SOI CORS

SOP for CORS Registration Process

Following are the steps needed to be followed to get registered for the CORS services:

Open Official SOI CORS Website in any browser. On the home page click on the Registration Button.
Keep all the documents ready that are required during the registration process. Select Region, Enter the Mobile Number, and click on Proceed.
Enter the OTP received on the mobile and click Verify OTP
Fill all required details and upload documents then Click on Submit.
After successful submission of the form, the acknowledgement number will be generated. It is also advised to keep the Acknowledgment Number for future reference.
It is advised to raise a query at the contact details given below if the user does not receive any information regarding the user account after 24 working hours.

Source and for More Info : SOI CORS

CORS Station Distribution Map for all CoE States:

CORS stations distribution in Uttarakhand State (Source: cors.surveyofindia.gov.in)

CORS stations distribution in Uttar Pradesh State (Source: cors.surveyofindia.gov.in)

CORS stations distribution in Bihar State (Source: cors.surveyofindia.gov.in)

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Topics :

Introduction
Key Features and Services of CORS
Standard Operation Procedure (SOP) for CORS Registration Process
CORS Station Distribution Map for all CoE StatesS

Field Survey Steps - An Overview

A field survey is a systematic process used to gather accurate spatial and geographical data for mapping, land assessment, and infrastructure planning. It involves several key steps to ensure precision and reliability.

1. Introduction

A field survey is an essential process in land management, urban planning, and construction, where data is gathered directly from the site. It involves systematic steps to ensure accurate measurements, reliable data collection, and precise mapping. By following these steps, surveyors can efficiently document spatial information, analyze terrain, and create detailed reports for decision-making. Below is an overview of the key steps involved in a field survey.

Planning & Preparation: Define objectives, choose equipment, and review existing data.
Reconnaissance (Recce): Visit the site to identify key landmarks and obstacles.
Establishing Control Points: Set up reference points which are going to be used during the actual data collection.
Data Collection: Measure distances, angles, and elevations using survey instruments.
Data Recording & Documentation: Log observations and measurements systematically.
Data Processing & Analysis: Convert raw data into maps, reports, and GIS databases.
Validation & Quality Check: Verify accuracy and make necessary corrections.
Final Reporting & Mapping: Present processed data in the form of maps or charts.

2. Field Survey of Land Parcel - Basics

A field survey of a land parcel is a crucial process in land management, real estate, and urban planning. It involves systematically measuring and mapping a specific land area to establish accurate boundaries, topographical features, and ownership details. The data collected through field surveys helps in legal documentation, infrastructure development, and decision-making.

2.1 Key Steps in a Land Parcel Survey

2.1.1. Pre-Survey Preparation

Define survey objectives (boundary identification, land division, etc.).
Gather land records, maps, and relevant documents.
Select appropriate survey equipment (GPS, total station, etc.).

2.1.2. Site Reconnaissance

Visit the site to assess topography and obstacles.
Mark key reference points for measurements.

2.1.3. Boundary Identification

Locate legal boundaries and verify records.
Mark boundary points with stakes or markers.

2.1.4. Measurement & Data Collection

Use GNSS, theodolite, or total station to measure distances and angles.
Record location coordinates and distances & angels with Total station.

2.1.5. Data Processing & Reporting

Analyze and validate collected data.
Generate maps, reports, and cadastral records.

Land parcel surveys are essential for accurate land ownership records, preventing disputes, and facilitating infrastructure planning. Modern technology like GNSS, Electronic Total Station, GIS and drones has improved survey efficiency and accuracy.

3. Tools Used for Land Survey

All field survey activities can be carried out by using field devices like survey grade GNSS Receivers (also known as GNSS Rovers), ETS (Electronic Total Station) with its accessories and Field data collectors. Tools like Enterprise GIS server through which data collected in the field can be directly integrated into the central database are also available. The method of survey and tools selection entirely depends on the terrain/ground conditions.

3.1. Understanding GNSS Receivers (GNSS Rovers)

A GNSS receiver, also known as a GNSS rover, is a device that helps determine precise locations on Earth. It is commonly used in land surveying, farming, construction, and mapping.

These receivers use signals from satellites in space to figure out their position. Some well-known satellite systems are:

NavIC (India) – India's own satellite navigation system, developed by ISRO for precise positioning in the Indian region. All following four systems are available globally. Hence all four are commonly put together called as Global Navigation Satellite Systems(GNSS).
GPS (USA)
GLONASS (Russia)
Galileo (Europe)
BeiDou (China)

To calculate an accurate location, a GNSS rover needs signals from at least four satellites. The device measures how long it takes for each satellite signal to reach it, then uses that information to find its position on the ground.

3.1.1 Why GNSS Needs Corrections?

If you use a GNSS device on its own, the location it gives may not be completely accurate. This happens because of various errors, such as:

Satellite timing issues
Delays caused by the atmosphere
Signal interference from buildings or trees

These errors can make the location several meters off, which is not good for tasks that require high precision, like construction or land surveys.

3.1.2 How We Improve Accuracy?

To get precise locations, GNSS rovers use correction data from special reference stations. There are two types:

CORS Network - These are SOI stations that continuously send correction data in real-time
GCPs (Ground Control Points) - Fixed locations with known coordinates that help adjust GNSS measurements.

3.1.3 How It Works in Simple Terms?

Imagine you're measuring a straight road with a regular tape measure, but the tape stretches and shrinks slightly due to heat. To get the exact length, you need a standard reference to compare against.

CORS and GCPs act like this standard reference for GNSS, helping remove errors and making location data super precise – down to a few centimeters!

With these corrections, GNSS receivers become much more reliable for surveying, mapping, and other applications that require accurate positioning.

3.1.4 How GNSS Rovers Work?

A GNSS Rover works by receiving signals from multiple satellite systems and compute their position.

Key Components of a GNSS Rover:

Antenna – Ensures receiving of weak signals from GNSS satellites and improves its power and transmits to the receiver.
GNSS Receiver – The core part that processes satellite signals to determine location.
Data Collector – Stores and processes location data, often running software for real-time mapping.
Communication Module – Connects to CORS correction services through radio or mobile networks, improving accuracy to the centimeter level using Network RTK (NRTK).
Durable Casing – Designed to withstand harsh weather and tough field conditions.

Rover and its components

3.2. Real-Time Kinematic (RTK) GNSS – High-Precision Positioning

RTK GNSS is an advanced positioning system that improves standard GNSS accuracy to centimeter-level precision. It works by using correction data from a reference station.

3.2.1 How RTK GNSS Works:?

Reference Station - A fixed GNSS receiver at a known location continuously tracks satellite signals and calculates corrections.
Rover Unit – A mobile GNSS receiver (GNSS Rover) collects satellite signals and receives real-time corrections from the reference station.
Real-Time Corrections - The rover applies these corrections, significantly improving positioning accuracy.

This system is widely used in land surveying, construction, precision farming, and mapping, where highly accurate location data is essential.

3.3. Electronic Total Station (ETS) with GNSS – Advanced Surveying Technology

Electronic Total Station (ETS) with GNSS combines two powerful surveying technologies to improve accuracy and efficiency in land measurement and mapping.

3.3.1 How it Works?

Electronic Total Station (ETS) - Measures angles (horizontal & vertical) and distances using laser or infrared technology.
GNSS (Global Navigation Satellite System) – Provides precise positional data by receiving signals from satellites.
Integrated System - Combining both technologies allows surveyors to achieve high-precision measurements over long distances, even in challenging terrains where one system alone may not be sufficient.

This hybrid system is widely used in land surveying, construction, infrastructure projects, and geospatial data collection, ensuring accurate and reliable results.

An Electronic Total Stations (ETS) with GNSS

3.4. Field Data Collector (FDC) with WebGIS for Field Survey

A Field Data Collector (FDC) is a specialized device or system used for collecting and recording GNSS/ETS data and/or GIS data (attributes) directly in the field. It enables surveyors to capture, update, and manage spatial and attribute data efficiently.

3.4.1 Key Features of FDC

Rugged Tablet or Device - Works seamlessly with GNSS Receivers (GNSS Rovers) or Electronic Total Stations (ETS) for accurate data collection.
Basemap Visualization & Feature Extraction – Allows surveyors to view maps and mark boundary points, land parcels, and other features in real-time.
Attribute Data Collection - Supports the linking of descriptive information (e.g., landowner details, land use, etc.) with spatial data.
WebGIS & Central Database Integration -
- Field devices connect to a central database through an Enterprise GIS Server, enabling real-time data transmission.
- Enhances efficiency in land management and ensures end-to-end digital workflow.
CORS Network Integration - Ensures high survey accuracy by receiving correction signals through a survey-grade GNSS Receiver.

This system significantly improves land surveying, cadastral mapping, and infrastructure planning, ensuring precise and up-to-date geographic data.

A Field Data Collector (FDC)

3.5. Distance-Distance Measurement using a Laser Range Finder

3.5.1 What it is?

A Laser Range Finder is a device that uses laser beams to measure distances accurately.

3.5.2 How it works?

It sends a laser beam to a target, and when the beam bounces back, the device calculates the exact distance.

3.5.3 Why it is used in land surveys?

Helps measure distances between points like property corners, slopes, and terrain features.
Useful when a point is not visible on the map / ORI.

3.5.4 How surveyors use it?

Measurements to the unknown point are taken from two points whose coordinates are known.
Distance from both known points to the unknown location are measured using LRF.
The exact position of unknown point is then computed using simple trigonometric formulae / by using software.

This method helps accurately map land features without needing to physically reach every point.

A LASER Range Finder Illustrative Image

3.6. Reference Stations – Correcting GPS/GNSS Errors

GPS/GNSS receivers can have errors due to satellite clock issues, atmospheric delays, receiver noise, and signal interference. These errors make location measurements inaccurate.

To fix this, GPS/GNSS data needs to be corrected using Reference Stations, which are fixed locations with accurately known coordinates. When the GNSS data is processed using reference station data, we can get accurate coordinates. The accuracy can be improved in two ways. One is using the Realtime corrections from a CORS network and the other way is post processing the GNSS data using GCP coordinates.

3.6.1 What it is?

There are two types of Reference Stations:

CORS Network (Continuous Operating Reference Stations) - A network of active stations providing real-time corrections (Refer chapter "Survey of India's CORS Service" in this module to read more about this CORS stations).
GCPs (Ground Control Points) - Fixed passive reference points used for post-processing corrections.

A CORS and GCP Illustrative Image

4. Field survey - Methodologies and Salient Instructions

For an example, let’s take a survey scenario of urban local body properties and plots.

4.1. Surveying Properties in a City – Simplified Steps

1.1 Gather Information:

Before starting, the survey team collects property documents, maps, tax records, and other legal details from the local government.
If there is an online city survey system (Web-GIS), it can be used to make the process smoother.

1.2. Prepare Maps & Tools:

The survey team carries printed and digital maps on specialized field devices (FDCs) or rugged laptops with GNSS software.
If the area of survey is having dense canopy or high-rise buildings which obstruct GNSS signals, it is necessary to carry other survey equipment like ETS / LRF / measuring tapes, to accurately measure and mark property boundaries.

1.3. Field Survey Process:

Existing maps and layout plans should be aligned correctly with real-world locations.
Reach to the location where property boundaries are to be measured on the field.
The teams takes photos of properties with high-resolution camera and ensure that it is geo-tagged.

1.4. Measuring Boundaries:

If physical markers like Boundary wall /fences exist, the center of these structures is considered the boundary unless proven otherwise

1.5. Using GNSS & Other Tools:

After identifying boundaries, the team uses GNSS rovers to measure the coordinates of the corners of the property accurately.
If boundaries are unclear on maps /ORI due to vegetation or other reasons, they are measured directly on the ground using GPS or other survey tools.
In areas where GNSS signals are obstructed (due to tall buildings, trees, or power lines), measurements are taken using alternative tools like Electronic Total Stations or measuring tapes.

1.6.Finalizing Property Data:

The collected data is processed and drawn on GIS software to create digital map of the property.
Each land parcel is assigned a temporary number until verified by local officials.
A final property ID is given after all approvals.

This ensures that all properties are properly recorded, mapped, and linked to government records for better city planning and management.

4.2. Field Survey: Salient Instructions

Survey team goes to the field with the basemaps, other available documents and identifies boundary markers or any physical landmarks on the ground and same should be correlated with basemap.
Ground team to visit each plot or land parcel to verify urban land boundaries. Boundary points are to be noted by the ground truthing team using GNSS Rover, in presence of land owners, and neighbors. Field survey team also validates the features extracted from the ORI such as utilities, buildings etc. on the ground.
Plot details as collected by the Field survey team on ground shall be tallied with the details contained in the attribute documents available with the land holders, which could include Record of Right, Sale Deed, Lease Deed, Gift Deed, Relinquishment Deed, Settlement Deed, Occupancy Certificate, Deed of Partition, Lay out Plan, Property Tax Receipt, Building Sanction Plan, Will, General Power of Attorney (GPA), Agreement to Sell(ATS), Utility Bills, Mutation Certificate, presented by the land holder in ownership possession of the plot/land parcel.

4.3. Field Survey Methodologies

Following are the Methodologies for Property Boundary/Land Parcel Survey by State Authorities:

4.3.1. FDC integrated with CORS network through NRTK receiver:

Marking Property Boundaries Using NRTK and CORS Network – Simplified Steps

How it works?
- Property boundaries are marked using Network RTK (NRTK) GNSS Rovers and a mobile application.
- The CORS network provides real-time corrections, improving accuracy.
- The surveyor can see the basemap on the Field Data Collector (FDC) and create digital property boundary maps on-site
Tools & Equipment Needed:
- CORS Network – Provides accurate GNSS corrections.
- NRTK GNSS Rovers – High-precision GNSS devices with tilt sensors.
- Field Data Collector (FDC) – Displays the basemap and records data.
- Laser Range Finder – Measures distances where GNSS signals are weak or difficult to receive due to the surrounding features.
- Printed Basemap – A hardcopy reference of property layouts.
- Trained Surveyors – Experts who operate the equipment GNSS / ETS / LRF / Tapes.

4.3.2. GNSS Receiver integrated with CORS Network:

Purpose of the Survey:
- Accurately mark property boundaries using advanced GNSS technology.
- Helps identify missing boundary points in existing maps.
Essential Equipment:
- CORS Network – Provides high-precision GNSS corrections.
- GNSS Rover (NRTK-enabled Receiver) – High-precision GNSS devices (with tilt sensors optional) which records accurate location data.
- Field Data Collector (FDC) – Rugged Laptop/tabs with GIS Software where viewing the plots boundary data in real-time are done.
- Laser Range Finder – Measures distances where GNSS signals are weak or difficult to receive due to the surrounding features.
- Printed Basemap – A hardcopy reference of property layouts which helps to compare new and old boundary data on ground.
- Trained Surveyors – Skilled surveyors to operate the equipment.
Field Survey Process:
- Surveyors visit the site with all necessary equipment.
- The GNSS Rover is placed at key boundary points to collect precise coordinates.
- If any points are missing from maps, measurements are taken using the Laser Range Finder.
Creating the Digital Property Map:
- Recorded GNSS coordinates are uploaded to GIS software on the rugged laptop.
- A property boundary layer is created in real-time.
- Surveyors verify the accuracy and make corrections if necessary.
Finalizing the Survey:
- The boundary data is reviewed and validated.
- The updated property boundaries are officially recorded.
- The final digital property map is submitted for approval.

This method ensures high-accuracy property mapping, minimizing errors and disputes

4.3.3. Electronic Total Stations in combination with GNSS:

Purpose of the Survey:
- To accurately mark property boundaries using Electronic Total Stations (ETS) and GNSS.
- This method ensures precise boundary mapping, even in areas where GNSS signals are weak or difficult to receive due to the surrounding features.
Essential Equipment:
- GNSS Instrument / CORS – Provides accurate reference points.
- Electronic Total Station (ETS) – Measures angles and distances with high precision.
- Rugged Laptop with GIS Softwar – Plots boundary data in real-time.
- Printed Basemap – A hardcopy reference of property layouts which helps to compare new and old boundary data.
- Trained Surveyors – Skilled surveyors to operate the equipment.
Field Survey Process:
- Step 1: Establish at least two Ground Control Points (GCPs) using GNSS Receivers (Rovers)
- Step 2: Align the Electronic Total Station using these GCPs.
- Step 3: Use the Total Station to record the exact coordinates of property boundary points.
Creating the Digital Property Map:
- The recorded coordinates are uploaded to GIS software on a rugged laptop.
- A property boundary layer is created and visualized in real-time.
- Any necessary corrections are made based on on-ground observations.
Finalizing the Survey:
- The boundary data is verified for accuracy.
- The updated property boundaries are officially recorded.
- The final digital property map is submitted for approval.

This method ensures high-accuracy property mapping, even in dense urban areas or regions with GNSS signals are obstructed.

4.3.4. Equipment Preparation:

GNSS Rover – Ensure the GNSS receiver is functional, charged, and updated with the latest firmware.
Field Data Collector (FDC) – – Install the appropriate software compatible with the GNSS Rover in the FDC and check Bluetooth, GPRS and Wi-Fi functionalities.
Power Backup – Carry spare batteries and portable chargers.
Connectivity – Confirm reliable internet access for the CORS network.

4.3.5. Define Survey Parameters:

Coordinate System – Use WGS-84 or a geographical projection system.
Survey Style – Configure GNSS receiver settings for RTK surveying.
Signal Tracking – Enable GNSS constellations (GPS, GLONASS, Galileo, Beidou, etc).
Elevation Mask – Set to 10–15 degrees to avoid low-angle satellites.
PDOP Mask – Set the threshold to <3 for high accuracy.
Verify NTRIP credentials – IP address, port, username, password, etc.

4.3.6. Survey Setup:

Mount the GNSS receiver on a tripod or pole and position it vertically using the bubble level.
Power on the receiver and check for satellite lock (at least 5 satellites for a 3D fix).

4.3.7. Establish Connection to CORS:

Primary way to establish communication between the rover and CORS networks is through Networked Transport of RTCM via Internet Protocol (NTRIP). This protocol allows the rover to connect to the CORS network through the internet.
Obtain NTRIP Access Information: Username and password provided by the Survey of India for accessing the CORS network corrections.
Configure the Rover: In the rover’s software or receiver settings, configure the NTRIP client by entering the caster URL, mount point, and login credentials.
Establish Connection: The rover will connect to the CORS network via the internet, receive RTK corrections, and apply them in real-time for improved accuracy.
Monitor the Connection: Ensure that the rover has an active connection to the CORS network and that it is receiving correction data

4.3.8. Pair the GNSS receiver with the Field Data Collector via Bluetooth:

Open Bluetooth settings and pair with the GNSS receiver (default PIN: 0000). Connect to the CORS network:

Enter the IP address and port of the CORS server.
Input NTRIP credentials (username and password)
Verify real-time corrections are active.

4.3.8. Establish Base Point (if required):

If a known control point is available, position the GNSS receiver over it.
Measure the point using RTK corrections to establish the reference for the survey.

4.3.8. Land Parcel Survey Execution - Boundary Point Measurement:

Step 1: Get Ready -
- Go to the first boundary point of the property.
- Set up the GNSS Rover and make sure it's stable.
Step 2: Accurate Positioning -
- Hold the survey pole straight (use the bubble level).
- Keep the antenna upright for a clear satellite signal.
- Enter the antenna height into the field device.
- Ensure a clear view of the sky for accurate measurements.
Step 3: Measuring the Boundary Points -
- Start measuring and wait for the device to confirm the position.
- Walk to each corner of the property and record the coordinates (latitude, longitude, elevation).
- For shared boundaries (with neighboring properties), measure only once to avoid differences.
Image Depicting Path Followed For Collection of Property Boundary Points Using GPS Rovers
Step 4: Special Cases – Corner Properties & Roadside Land -
- If a property is at a road intersection, measure all road-facing sides carefully.
- If a boundary overlaps with a building, review and verify with a supervisor.
- Locate and record the roadside boundary points with high precision.
Step 5: Checking for Accuracy -
- Compare new measurements with old maps — adjust if the difference is more than 5 cm.
- Ignore small differences (less than 10 cm) but correct any major variation (over 50 cm).
- If a measurement places a boundary over a building (wrong position), it must be rechecked and corrected.
Step 6: Handling Difficult Areas -
- Use offset measurements for blocked points (e.g., behind walls or canopy covered areas).
- Re-measure if accuracy limits are not met.
Step 7: Finalizing the Survey -
- Calculate the total area of the property in the survey software.
- Add details like owner’s name, survey number, and tax details in the attributes collector fields.
- Take a photo of the property’s front view and make sure its geotagged.
- Move to the next property and repeat the processes.

4.3.9. Post-Survey Tasks - Data Export:

Export the collected data from the Field Data Collector to the system
Format: CSV, DXF, or SHP (depending on project requirements).
Projection: UTM projection with datum WGS-84 or local coordinate system.
Save data securely in multiple locations (e.g., cloud storage, USB drives) and make sure there are ample backups of the collected data.

4.3.10. Surveyed Data Processing:

Import data into GIS or CAD software for analysis and mapping.
Process RTK and raw data in the GNSS software (Trimble Business Center for Trimble make) or equivalent software
Perform baseline processing and network adjustment.
Verify data consistency and accuracy.

4.3.11. Metadata Creation, Parcel Layout and Report Generation:

Prepare detailed maps showing parcel boundaries, coordinates and area of the land parcel metadata.
Include metadata.
Measurement accuracy (horizontal and vertical).
Coordinate system and datum.
CORS network details and reference points used.
Area of the land parcel.

4.3.12. Best Practices:

Equipment Maintenance: Regularly calibrate GNSS receivers and ensure proper battery charging.
Signal Monitoring: Avoid surveying during high PDOP conditions or satellite outages.
Safety Protocols: Follow safety guidelines in remote or hazardous survey areas.
Backup the data: Survey team must ensure that survey data is stored in proper devices.

First Previous Next Last

Topics :

Introduction
Field Survey of Land Parcel - Basics
Tools Used for Land Survey
Field survey - Methodologies and Salient Instructions

Welcome to Chapter 3 : Field Survey Steps - An Overview

A field survey is a systematic process used to gather accurate spatial and geographical data for mapping, land assessment, and infrastructure planning.
It involves several key steps to ensure precision and reliability.

1. Introduction

Planning & Preparation: Define objectives, choose equipment, and review existing data.
Reconnaissance (Recce): Visit the site to identify key landmarks and obstacles.
Establishing Control Points: Set up reference points for accurate measurements.
Data Collection: Measure distances, angles, and elevations using survey instruments.
Data Recording & Documentation: Log observations and measurements systematically.
Data Processing & Analysis: Convert raw data into maps, reports, and GIS databases.
Validation & Quality Check: Verify accuracy and make necessary corrections.
Final Reporting & Mapping: Present processed data in the form of maps or charts.

2. Field Survey of Land Parcel - Basics

2.1 Key Steps in a Land Parcel Survey

2.1.1. Pre-Survey Preparation

Define survey objectives (boundary identification, land division, etc.).
Gather land records, maps, and relevant documents.
Select appropriate survey equipment (GPS, total station, etc.).

2.1.2. Site Reconnaissance

Visit the site to assess topography and obstacles.
Mark key reference points for measurements.

2.1.3. Boundary Identification

Locate legal boundaries and verify records.
Mark boundary points with stakes or markers.

2.1.4. Measurement & Data Collection

Use GNSS, theodolite, or total station to measure distances and angles.
Record GPS coordinates and survey data.

2.1.5. Data Processing & Reporting

Analyze and validate collected data.
Generate maps, reports, and cadastral records.

Land parcel surveys are essential for accurate land ownership records, preventing disputes, and facilitating infrastructure planning. Modern technology like GNSS, GIS, and drones has improved survey efficiency and accuracy.

3. Tools Used for Land Survey

All field survey activities can be carried out by using field devices like survey grade GNSS Receivers (also known as GNSS Rovers) in NRTK/Static Mode integrated with/without field data collector connected to Central Database through an enterprise GIS Server in online/offline mode, ETS GNSS etc. depending on the terrain conditions and availability of the instruments.

3.1. Understanding GNSS Receivers (GNSS Rovers)

A GNSS receiver, also known as a GNSS rover, is a device that helps determine precise locations on Earth. It is commonly used in land surveying, farming, construction, and mapping.

These receivers use signals from satellites in space to figure out their position. Some well-known satellite systems are:

GPS (USA)
NavIC (India) – India's own satellite navigation system, developed by ISRO for precise positioning in the Indian region.
GLONASS (Russia)
Galileo (Europe)
BeiDou (China)

To calculate an accurate location, a GNSS rover needs signals from at least four satellites. The device measures how long it takes for each satellite signal to reach it, then uses that information to find its position on the ground.

3.1.1 Why GNSS Needs Corrections?

If you use a GNSS device on its own, the location it gives may not be completely accurate. This happens because of various errors, such as:

Satellite timing issues
Delays caused by the atmosphere
Signal interference from buildings or trees

These errors can make the location several meters off, which is not good for tasks that require high precision, like construction or land surveys.

3.1.2 How We Improve Accuracy?

To get precise locations, GNSS rovers use correction data from special reference stations. There are two types:

CORS Network - These are SOI stations that continuously send correction data in real-time
GCPs (Ground Control Points) - Fixed locations with known coordinates that help adjust GNSS measurements.

3.1.3 How It Works in Simple Terms?

CORS and GCPs act like this standard reference for GNSS, helping remove errors and making location data super precise – down to a few centimeters!

With these corrections, GNSS receivers become much more reliable for surveying, mapping, and other applications that require accurate positioning.

3.1.4 How GNSS Rovers Work?

A GNSS Rover is a high-tech device used to find precise locations on Earth. It works by receiving signals from multiple satellite systems like GPS (USA), GLONASS (Russia), Galileo (Europe), BeiDou (China), and NavIC (India).

Key Components of a GNSS Rover:

GNSS Receiver – The core part that processes satellite signals to determine location.
High-Performance Antenna – Ensures strong and reliable signal reception, even in cities or dense forests.
Data Collector – Stores and processes location data, often running software for real-time mapping.
Communication Module – Connects to CORS correction services through radio or mobile networks, improving accuracy to the centimeter level using Network RTK (NRTK).
Durable Casing – Designed to withstand harsh weather and tough field conditions.

Rover and its components

3.2. Real-Time Kinematic (RTK) GPS – High-Precision Positioning

RTK GPS is an advanced positioning system that improves standard GPS accuracy to centimeter-level precision. It works by using correction data from a reference station.

3.2.1 How RTK GPS Works:?

Reference Station - A fixed GPS receiver at a known location continuously tracks satellite signals and calculates corrections.
Rover Unit – A mobile GPS receiver (GNSS Rover) collects satellite signals and receives real-time corrections from the reference station.
Real-Time Corrections - The rover applies these corrections, significantly improving positioning accuracy.

This system is widely used in land surveying, construction, precision farming, and mapping, where highly accurate location data is essential.

3.3. Electronic Total Station (ETS) with GNSS – Advanced Surveying Technology

Electronic Total Station (ETS) with GNSS combines two powerful surveying technologies to improve accuracy and efficiency in land measurement and mapping.

3.3.1 How it Works?

Electronic Total Station (ETS) - Measures angles (horizontal & vertical) and distances using laser or infrared technology.
GNSS (Global Navigation Satellite System) – Provides precise positional data by receiving signals from satellites.
Integrated System - Combining both technologies allows surveyors to achieve high-precision measurements over long distances, even in challenging terrains where one system alone may not be sufficient.

This hybrid system is widely used in land surveying, construction, infrastructure projects, and geospatial data collection, ensuring accurate and reliable results.

An Electronic Total Stations (ETS) with GNSS

3.4. Field Data Collector (FDC) with WebGIS for Field Survey

A Field Data Collector (FDC) is a specialized device or system used for collecting and recording GIS data directly from the field. It enables surveyors to capture, update, and manage spatial and attribute data efficiently.

3.4.1 Key Features of FDC

Rugged Tablet or Device - Works seamlessly with GNSS Receivers (GNSS Rovers) or Electronic Total Stations (ETS) for accurate data collection.
Basemap Visualization & Feature Extraction – llows surveyors to view maps and mark boundary points, land parcels, and other features in real-time.
Attribute Data Collection - Supports the linking of descriptive information (e.g., landowner details, land use, etc.) with spatial data.
WebGIS & Central Database Integration -
- Field devices connect to a central database through an Enterprise GIS Server, enabling real-time data transmission.
- Enhances efficiency in land management and ensures end-to-end digital workflow.
CORS Network Integration - Ensures high survey accuracy by receiving correction signals through a survey-grade GNSS Receiver.

This system significantly improves land surveying, cadastral mapping, and infrastructure planning, ensuring precise and up-to-date geographic data.

A Field Data Collector (FDC)

3.5. Distance-Distance Measurement using a Laser Range Finder

3.5.1 What it is?

A Laser Range Finder is a device that uses laser beams to measure distances accurately.

3.5.2 How it works?

It sends a laser beam to a target, and when the beam bounces back, the device calculates the exact distance.

3.5.3 Why it is used in land surveys?

Helps measure distances between points like property corners, slopes, and terrain features.
Useful when a point is not visible on the map.

3.5.4 How surveyors use it?

They stand at two well-known points.
Measure the distance from both points to the unknown location.
The exact position is then determined on a digital map using special software.

This method helps accurately map land features without needing to physically reach every point.

A LASER Range Finder Illustrative Image

3.6. Reference Stations – Correcting GPS/GNSS Errors

GPS/GNSS receivers can have errors due to satellite clock issues, atmospheric delays, receiver noise, and signal interference. These errors make location measurements inaccurate.

To fix this, GPS/GNSS data needs to be corrected using Reference Stations, which are fixed locations with accurately known coordinates. These stations provide correction data to improve accuracy.

3.6.1 What it is?

There are two types of Reference Stations:

CORS Network (Continuous Operating Reference Stations) - A network of active stations providing real-time corrections (Refer previous chapter "Survey of India's CORS Service" in this module to read more about this CORS stations).
GCPs (Ground Control Points) - Fixed passive reference points used for post-processing corrections.

A CORS and GCP Illustrative Image

4. Field survey - Methodologies and Salient Instructions

For an example, let’s take a survey scenario of urban local body properties and plots.

4.1. Surveying Properties in a City – Simplified Steps

1.1 Gather Information:

Before starting, the survey team collects property documents, maps, tax records, and other legal details from the local government.
If there is an online city survey system (Web-GIS), it can be used to make the process smoother.

1.2. Prepare Maps & Tools:

Existing maps and layout plans should be aligned correctly with real-world locations.
The team carries printed and digital maps on specialized field devices (FDCs) or rugged laptops with GPS software.
If GPS is not available, high-precision survey equipment (GNSS Rovers, Total Stations) is used to mark property boundaries.

1.3. Field Survey Process:

Existing maps and layout plans should be aligned correctly with real-world locations.
The team carries printed and digital maps on specialized field devices (FDCs) or rugged laptops with GPS software.
If GPS is not available, high-precision survey equipment (GNSS Rovers, Total Stations) is used to mark property boundaries.

1.4. Measuring Boundaries:

If physical markers like fences exist, the center of these structures is considered the boundary unless proven otherwise.
The team takes photos of properties with high-resolution camera, and ensure that it is geo-tagged.

1.5. Using GPS & Other Tools:

After identifying boundaries, the team uses GNSS rovers (high-precision GPS) to measure the property accurately.
If boundaries are unclear on maps, they are measured directly on the ground using GPS or other survey tools.
In areas where GPS doesn’t work well (due to tall buildings, trees, or power lines), measurements are taken using alternative tools like Electronic Total Stations or measuring tapes.

1.6.Finalizing Property Data:

The collected data is processed and drawn on GIS software to create digital property maps.
Each land parcel is assigned a temporary number until verified by local officials.
A final property ID is given after all approvals.

This ensures that all properties are properly recorded, mapped, and linked to government records for better city planning and management.

4.2. Field Survey: Salient Instructions

Survey team goes to the field with the basemap and identifies as well as documents boundary markers or any physical landmarks on the ground and same should be correlated with basemap.
Ground team to visit each plot or land parcel to verify urban land boundaries. Boundary points are to be noted by the ground truthing team using GNSS Rover, in presence of land owners, and neighbors. Field survey team to also ground validate the features extracted from the ORI such as utilities, buildings etc.
Collection of the plot details available with the survey team shall be tallied with the details contained in the attribute documents available with the land holders, which could include Record of Right, Sale Deed, Lease Deed, Gift Deed, Relinquishment Deed, Settlement Deed, Occupancy Certificate, Deed of Partition, Lay out Plan, Property Tax Receipt, Building Sanction Plan, Will, General Power of Attorney (GPA), Agreement to Sell(ATS), Utility Bills, Mutation Certificate, presented by the land holder in ownership possession of the plot/land parcel.

4.3. Field Survey Methodologies

Following are the Methodologies for Property Boundary/Land Parcel Survey by StateAuthorities:

4.3.1. FDC integrated with CORS networkthrough NRTK receiver:

Marking Property Boundaries Using NRTK and CORS Network – Simplified Steps

How it works?
- Property boundaries are marked using Network RTK (NRTK) GNSS Rovers and a mobile application.
- The CORS network provides real-time corrections, improving accuracy.
- The surveyor can see the basemap on the Field Data Collector (FDC) and create digital property boundary maps on-site
Tools & Equipment Needed:
- CORS Network – Provides accurate GPS corrections.
- NRTK GNSS Rovers – High-precision GPS devices with tilt sensors.
- Field Data Collector (FDC) – Displays the basemap and records data.
- Laser Range Finder – Measures distances where GPS signals are weak.
- Printed Basemap – A hardcopy reference of property layouts.
- Trained Surveyors – Experts who operate the equipment.

4.3.2. GNSS Receiver integrated with CORS Network:

Purpose of the Survey:
- Accurately mark property boundaries using advanced GNSS technology.
- Helps identify missing boundary points in existing maps.
Essential Equipment:
- CORS Network – Provides high-precision GPS corrections.
- GNSS Rover (NRTK-enabled Receiver) – High-precision GPS devices with tilt sensors which records accurate location data.
- Field Data Collector (FDC) – Rugged Laptop/tabs with GIS Software where viewing the plots boundary data in real-time are done.
- Laser Range Finder – Measures distances where GPS signals are weak.
- Printed Basemap – A hardcopy reference of property layouts which helps to compare new and old boundary data.
- Trained Surveyors – Skilled surveyors to operate the equipment.
Field Survey Process:
- Surveyors visit the site with all necessary equipment.
- The GNSS Rover is placed at key boundary points to collect precise coordinates.
- If any points are missing from maps, measurements are taken using the Laser Range Finder.
Creating the Digital Property Map:
- Recorded GPS coordinates are uploaded to GIS software on the rugged laptop.
- A property boundary layer is created in real-time.
- Surveyors verify the accuracy and make corrections if necessary.
Finalizing the Survey:
- The boundary data is reviewed and validated.
- The updated property boundaries are officially recorded.
- The final digital property map is submitted for approval.

This method ensures high-accuracy property mapping, minimizing errors and disputes

4.3.3. Electronic Total Stations in combination with GNSS:

Purpose of the Survey:
- To accurately mark property boundaries using Electronic Total Stations (ETS) and GNSS.
- This method ensures precise boundary mapping, even in areas where GNSS signals are weak.
Essential Equipment:
- GNSS Instrument / CORS – Provides accurate reference points.
- Electronic Total Station (ETS) – Measures angles and distances with high precision.
- Rugged Laptop with GIS Softwar – Plots boundary data in real-time.
- Laser Range Finder – Measures distances where GPS signals are weak.
- Printed Basemap – A hardcopy reference of property layouts which helps to compare new and old boundary data.
- Trained Surveyors – Skilled surveyors to operate the equipment.
Field Survey Process:
- Step 1: Establish at least two Ground Control Points (GCPs) using GNSS Receivers (Rovers)
- Step 2: Align the Electronic Total Station using these GCPs.
- Step 3: Use the Total Station to record the exact coordinates of property boundary points.
- Step 4: If any points are missing from existing maps, measure them using the Laser Range Finder.
Creating the Digital Property Map:
- The recorded coordinates are uploaded to GIS software on a rugged laptop.
- A property boundary layer is created and visualized in real-time.
- Any necessary corrections are made based on on-ground observations.
Finalizing the Survey:
- The boundary data is verified for accuracy.
- The updated property boundaries are officially recorded..
- The final digital property map is submitted for approval.

This method ensures high-accuracy property mapping, even in dense urban areas or regions with weak GNSS signals.

4.3.4. Equipment Preparation:

GNSS Rover Setup – Ensure the GNSS receiver is functional, charged, and updated withthe latest firmware.
Field Data Collector (FDC) – Install survey software (e.g., Trimble Access) and check Bluetooth, GPRS and Wi-Fi functionalities.
Power Backup – Carry spare batteries and portable chargers.
Connectivity – Confirm reliable internet access for the CORS network.

4.3.5. Define Survey Parameters:

Coordinate System – Use WGS-84 or a geographical projection system.
Survey Style – Configure GNSS receiver settings for RTK surveying.
Signal Tracking – Enable GNSS constellations (GPS, GLONASS, Galileo, NavIC, etc.).
Elevation Mask – Set to 10–15 degrees to avoid low-angle satellites.
PDOP Mask – Set the threshold to <3 for high accuracy.
Verify NTRIP – credentials (IP address, port, username, and password).

4.3.6. Survey Setup:

Mount the GNSS receiver on a tripod or pole and position it vertically using the bubblelevel.
Power on the receiver and check for satellite lock (at least 5 satellites for a 3D fix).

4.3.7. Establish Connection to CORS:

Primary ways to establish communication between the rover and CORS networks viainternet Networked Transport of RTCM via Internet Protocol (NTRIP). This method allowsthe rover to connect to the CORS network through the internet.
Obtain NTRIP Access Information: Contact the CORS provider or use a public NTRIPservice. You will need an NTRIP caster URL, a username, and password (if required), andthe specific mount point of the CORS station.
Configure the Rover: In the rover’s software or receiver settings, configure the NTRIPclient by entering the caster URL, mountpoint, and login credentials.
Establish Connection: The rover will connect to the CORS network via the internet,receive RTK corrections, and apply them in real-time for improved accuracy.
Monitor the Connection: Ensure that the rover has an active connection to the CORS network and that it is receiving correction data

4.3.8. Pair the GNSS receiver with the Field Data Collector via Bluetooth:

Open Bluetooth settings and pair with the GNSS receiver (default PIN: 0000). Connect to the CORS network:

Enter the IP address and port of the CORS server.
Input NTRIP credentials (username and password)
Verify real-time corrections are active.

4.3.8. Establish Base Point (if required):

If a known control point is available, position the GNSS receiver over it.
Measure the point using RTK corrections to establish the reference for the survey.

4.3.8. Land Parcel Survey Execution - Boundary Point Measurement:

Step 1: Get Ready -
- Go to the first boundary point of the property.
- Set up the GNSS Rover and make sure it's stable.
Step 2: Accurate Positioning -
- Hold the survey pole straight (use the bubble level).
- Keep the antenna upright for a clear satellite signal.
- Enter the antenna height into the field device.
- Ensure a clear view of the sky for accurate measurements.
Step 3: Measuring the Boundary Points -
- Start measuring and wait for the device to confirm the position.
- Walk to each corner of the property and record the coordinates (latitude, longitude, elevation).
- For shared boundaries (with neighboring properties), measure only once to avoid differences.
Image Depicting Path Followed For Collection of Property Boundary Points Using GPS Rovers
Step 4: Special Cases – Corner Properties & Roadside Land -
- If a property is at a road intersection, measure all road-facing sides carefully.
- If a boundary overlaps with a building, review and verify with a supervisor.
- Locate and record the roadside boundary points with high precision.
Step 5: Checking for Accuracy -
- Compare new measurements with old maps — adjust if the difference is more than 5 cm.
- Ignore small differences (less than 10 cm) but correct any major variation (over 50 cm).
- If a measurement places a boundary over a building (wrong position), it must be rechecked and corrected.
Step 6: Handling Difficult Areas -
- Use offset measurements for blocked points (e.g., behind walls).
- Re-measure if accuracy limits are not met.
Step 7: Finalizing the Survey -
- Calculate the total area of the property in the survey software.
- Add details like owner’s name, survey number, and tax details in the attributes collector fields.
- Take a photo of the property’s front view and make sure its geotagged.
- Move to the next property and repeat the processes.

4.3.9. Post-Survey Tasks - Data Export:

Export the collected data from the Field Data Collector to the system
Format: CSV, DXF, or SHP (depending on project requirements).
Projection: UTM projection with datum WGS-84 or local coordinate system.
Save data securely in multiple locations (e.g., cloud storage, USB drives) and make sure there are ample backups of the collected data.

4.3.10. Surveyed Data Processing:

Import data into GIS or CAD software for analysis and mapping.
Process RTK and raw data in Trimble Business Center (TBC) or equivalent software.
Perform baseline processing and network adjustment.
Verify data consistency and accuracy.

4.3.11. Metadata Creation, Parcel Layoutand Report Generation:

Prepare detailed maps showing parcel boundaries, coordinates and area of the land parcel metadata.
Include metadata.
Measurement accuracy (horizontal and vertical).
Coordinate system and datum.
CORS network details and reference points used.
Area of the land parcel.

4.3.12. Best Practices:

Equipment Maintenance: Regularly calibrate GNSS receivers and ensure proper storage.
Signal Monitoring: Avoid surveying during high PDOP conditions or satellite outages.
Safety Protocols: Follow safety guidelines in remote or hazardous survey areas.
Backup the data: Survey team must ensure that survey data is stored in proper devices.

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Topics :

Introduction
Field Survey of Land Parcel - Basics
Tools Used for Land Survey
Field survey - Methodologies and Salient Instructions