eLEARNING - Land Survey and Management

Welcome to Chapter 1 : Introduction to Geo-Referencing

Understanding the concept of Geo-Referencing.

Geo-referencing is the process of assigning real-world geographic coordinates to spatial data, such as maps, images, etc. By linking a dataset to a specific location on the Earth’s surface, geo-referencing ensures that it can be accurately displayed, analyzed, and compared with other geographic information. This process is essential in GIS for integrating different datasets and creating meaningful spatial analyses.

Geo-referencing can be explained as a pin on a map to show exactly where something is. Just like dropping a location pin on Google Maps so you can find a shop or a friend’s house, This makes it possible to line up old maps, satellite images, etc., with today’s maps, so they all match correctly and can be used together.

Geo-referencing connects an image or map to real-world coordinates. This ensures that the data is measurement-ready and can be matched accurately with its real-world location.

1.2 Purpose of Geo-Referencing

Assigns real-world location : Georeferencing gives maps, images a real-world context by linking them to geographic coordinates. Without this step, scanned maps or satellite images are simply pictures with no spatial reference. By assigning actual latitude and longitude values, these visuals can be accurately placed on the Earth’s surface, ensuring that every feature, whether it’s a road, building, or river, corresponds to its correct location in reality.
Makes data measurement-ready : Once an image or map is georeferenced, it becomes a measurable dataset rather than just a visual aid. This means that users can calculate distances between points, measure areas of land parcels, and determine accurate positions with confidence. For example, in land survey or urban planning, knowing the precise measurements of plots or the distance between infrastructure elements is crucial for design, analysis, and execution.
Enables integration : Georeferencing allows different types of spatial datasets to be aligned and compared within the same coordinate system. This is particularly important when working with historical maps, satellite imagery, survey records, and modern GIS data. By standardizing their spatial references, these datasets can be overlaid seamlessly, enabling comprehensive analysis that reveals changes over time or relationships between diverse sources of geographic information.
Supports decision-making : Reliable georeferenced data empowers decision-makers in fields like urban planning, environmental management, disaster response, and infrastructure development. By providing spatially accurate information, it helps planners visualize scenarios, assess risks, and develop strategies that are grounded in real-world conditions. For example, city planners can use georeferenced maps to decide where to expand infrastructure, while environmental agencies can monitor deforestation or flood-prone areas with higher precision.

1.3 Tools used for Geo-Referencing

As we all know that every task needed to be done on the Computer, the tasks are done through the Software applications. In that manner the Geo-Referencing of the data is done using several tools present in the GIS/CAD softwares as mentioned below:

Open-source & free tools QGIS, GDAL.
Commercial tools ArcGIS, ERDAS IMAGINE, Global Mapper, AutoCAD Map 3D.

QGIS Georeferencer Plugin :
- An open-source tool built into QGIS.
- Supports both the methods of Geo-Referencing.
- Supports assigning Ground Control Points (GCPs), applying transformations, and exporting georeferenced raster images.
- Ideal for academic, professional, and government use due to its free availability.
ArcGIS Georeferencing Tool :
- A widely used proprietary tool by Esri.
- Supports both the methods of Geo-Referencing.
- Provides advanced georeferencing options, including multiple transformation methods (like Adjust, etc).
ERDAS IMAGINE :
- A powerful remote sensing and image analysis software.
- Supports both the methods of Geo-Referencing.
Global Mapper :
- A GIS software with user-friendly georeferencing features.
- Supports both the methods of Geo-Referencing.
- Supports a wide range of raster and vector formats.
- Often used for quick alignment tasks and integration with GPS data.
GDAL (Geospatial Data Abstraction Library) :
- An open-source command-line library for raster and vector data processing.
- Supports both the methods of Geo-Referencing.
- Provides powerful utilities like gdal_translate and gdalwarp for georeferencing and reprojection.
- Preferred by developers and advanced users for automation and scripting.
AutoCAD Map 3D / Civil 3D :
- Engineering-focused tools that allow georeferencing of CAD drawings.
- Useful for aligning engineering designs and construction layouts with GIS datasets.

First Previous Next Last

Topics :

1.1 Introduction
1.2 Purpose of Geo-referencing
1.3 Tools Used for Geo-referencing

Welcome to Chapter 2 : Geo-referencing using Ground Control Points (GCPs)

Step by Step process explained for the Geo-Referencing using GCPs - Utilizing the tool available in QGIS Software

2.1. Introduction

QGIS (Quantum GIS) provides powerful tools for georeferencing raster images (e.g., scanned maps, aerial photos) to align them with real-world coordinates. The Georeference tool in QGIS allows for multiple techniques, each suitable for different types of spatial distortions.

Things to keep ready before starting the step-by-step process:

QGIS Software installed and opened on the computer system.
Open the installed QGIS Application.
Target Image or Raster data: On which the Geo-Referencing has to be done.
Set of GCPs in any of the GIS Vector Data formats.

Georeferencing using Ground Control Points (GCPs) in QGIS is a common method to align an unreferenced raster (e.g., scanned maps, aerial photos) with a known coordinate system. This technique ensures that the raster image accurately assigning the precise coordinates for spatial alignment.

2.2. Steps for Georeferencing with GCPs in QGIS

Following are the steps involved in the process of GeoReferencing using the GCPs method utilizing the "Georeferencer" Tool in the QGIS software.

1. Open QGIS and Load Reference Data

Add a basemap, vector layer, or georeferenced raster as a reference.
For online basemaps, use XYZ Tiles (e.g., Google Satellite, OpenStreetMap).
Navigate to QGIS Plugins Basemap Management Load Basemaps on the Menu Bar as shown in the below images

Set Projection Co-ordinate Reference System (CRS) as per the requirement

2. Open the Georeferencer Tool

Navigate to QGIS Layer Georeferencer... on the Menu Bar as shown in the below image.
Click on the Georeferencer... link to open the tool to be used for georeferencing of the image

3. Load Source Raster (Unreferenced Image)

On the opened Georeferencer tool, click Open Raster... and select the scanned map or aerial image, etc., which is to be georeferenced, as shown in the below image

4. Add Ground Control Points (GCPs)

Click Add GCP Point from the Tool Box Menu on the Georeferencer window as shown in the below image to open the "Enter Map Coordinates" window

In the "Enter Map Coordinates" window:
- If using a georeferenced layer (e.g., basemap), click From Map Canvas and pick the same location.
- If having GCP coordinates (longitude/latitude), manually enter them on the fields "X/Easting" & "Y/Northing".
- Select the CRS based on the requirement

Repeat this for at least 4 control points distributed evenly across the image. As shown in the below image.
This is the important step to be done. If the GCPs are not distributed on all over the image, and less than 4 GCPs are used, it will result in an very low accuracy of the output image.

5. Choose the Transformation Method

Click Transformation Settings... by navigating to Settings Transformation Settings... on the Menu Bar of the Georeferencer window as shown in the below image to open the "Transformation Settings" window

In the opened Transformation Settings window, select a transformation type:
- Affine Transformation (Minimum 3 GCPs; for basic scaling, rotation, translation).
- Polynomial (1st or 2nd Order) (For slight distortions; requires 6+ GCPs).
- Thin Plate Spline (Rubber Sheeting) (For flexible warping; good for historical maps).
- Projective Transformation (For perspective distortions; requires 4+ GCPs).

6. Set Output Parameters

Choose:
- Output format: GeoTIFF (recommended).
- Resampling method:
  - Nearest Neighbor (for categorical data like scanned maps).
  - Bilinear or Cubic (for continuous data like aerial images).
- Coordinate Reference System (CRS): Choose a CRS based on the project requirements

7. Start Georeferencing

Click "Start Georeferencing" on the Tool Bar Menu of the "Georeferencer" window.
QGIS will generate a georeferenced raster.

8. Verify Accuracy

Overlay the georeferenced raster with the reference layer.
Check the Root Mean Square Error (RMSE) in the Georeferencer window
- A lower RMSE indicates better accuracy (<=1 pixel or as low as possible)..
- If RMSE is high, adjust GCPs and re-run the process

First Previous Next Last

Topics :

2.1. Introduction
2.2. Steps for Georeferencing with GCPs in QGIS
2.3. Georeferencing using GCPs explained in a concise tabular steps

Welcome to Chapter 3 : Geo-referencing Using Image-to-Image

3.1. Introduction

Image-to-Image geo-referencing is the process of aligning one image (such as a scanned map or satellite image) with another image that already has real-world coordinates. Instead of using ground control points from the field, you pick matching points on both images (like road intersections, rivers, or landmarks) and link them together.

This way, the “unknown” image inherits the geographic reference from the “known” image, making it location-ready and usable for measurement, analysis, or overlay with other GIS datasets.

Things to keep ready before starting the step-by-step process:

QGIS Software installed and opened on the computer system.
Open the installed QGIS Application.
Target Image or Raster data: On which the Geo-Referencing has to be done.
Reference image using which the georeferencing is to be done.

3.2. Steps for Georeferencing with Image-to-image in QGIS

1. Open QGIS and Load Reference Data

Open QGIS and add the georeferenced raster image (reference image) by navigating to QGIS Layer Add Layer Add Raster Layer... on the Menu Bar as shown in the below images

Set Projection Co-ordinate Reference System (CRS) as per the requirement (EPSG:4326 - WGS84)

2. Open the Georeferencer Tool

Navigate to QGIS Layer Georeferencer... on the Menu Bar as shown in the below image.

Click on the Georeferencer... link to open the tool to be used for georeferencing of the image

3. Load Source Raster (Unreferenced Image)

On the opened Georeferencer tool, click Open Raster... and select the scanned map or aerial image, etc., which is to be georeferenced, as shown in the below image

4. Add Control Points

Click Add Point and select recognizable locations on the unreferenced image

In the Enter Map Coordinates window, click "From Map Canvas".

Select the same location in the reference image.

Repeat this for multiple control points (at least 4 for better accuracy).

5. Choose the Transformation Method

Click Transformation Settings... by navigating to Settings Transformation Settings... on the Menu Bar of the Georeferencer window as shown in the below image to open the "Transformation Settings" window

In the opened Transformation Settings window, select a transformation type:

Affine Transformation (Minimum 3 GCPs; for basic scaling, rotation, translation).

Polynomial (1st or 2nd Order) (For slight distortions; requires 6+ GCPs).

Thin Plate Spline (Rubber Sheeting) (For flexible warping; good for historical maps).

Projective Transformation (For perspective distortions; requires 4+ GCPs).

6. Set Output Parameters

Choose:

Output format: GeoTIFF (recommended).

Coordinate Reference System (CRS): Choose a CRS based on the project requirements

Enable Load in QGIS when done.

7. Start Georeferencing

Click "Start Georeferencing" on the Tool Bar Menu of the "Georeferencer" window to start the georeferencing process.

QGIS will generate a georeferenced raster.

8. Verify Alignment

Overlay the newly georeferenced raster with the reference layer.

If misaligned, adjust control points and re-run.

First Previous Next Last

Topics :

3.1. Introduction

3.2. Steps for Georeferencing with Image-to-image in QGIS

Welcome to Chapter 4 : Cool Things You Can Do With GIS

4.1. Introduction

Once you understand how GIS works, you’ll realize that its possibilities are endless. GIS is not just for geographers — it’s for everyone who wants to make smarter decisions using location information.

Some cool applications:

Shortest Route Calculation: Delivery apps like Zomato, Uber, and Amazon use GIS to find the best routes. They calculate distances, traffic conditions, and even weather to optimize deliveries.

Urban Planning: Cities use GIS to decide where to build new schools, parks, and hospitals. They analyze population densities, land prices, road networks, and existing facilities to make smarter plans.

Wildlife Protection: Conservationists map forest cover, track animal movements, and identify areas under threat. GIS helps in designing wildlife corridors and protecting endangered species.

Disaster Management: During floods, earthquakes, or fires, GIS provides real-time maps showing affected areas, shelters, and safe evacuation routes. It helps save lives by giving quick, accurate information.

Climate Change Studies: Scientists use GIS to study how glaciers are melting, how rainfall patterns are changing, and how sea levels are rising. GIS helps visualize slow changes over decades.

4.2. Create Smart Maps & Analyze Spatial Data

4.2.1. Create Smart Maps:

GIS enables the layering of various kinds of geographic information into a single, unified visual display. These smart maps are dynamic, they don't just show roads or rivers but can also include population density, crime rates, or soil types depending on the purpose. This layered approach makes it easier to see relationships, patterns, and trends that might otherwise go unnoticed.

For example, during urban development, a smart map can show where population is growing, how close areas are to public utilities, or which regions have environmental restrictions. These insights help decision-makers take smarter, more sustainable actions.

4.2.2. Analyze Spatial Data:

One of the strongest features of GIS is its ability to answer spatial questions—such as “What is near this point?”, “How far is location A from location B?”, or “What lies within this boundary?” These questions are critical in fields ranging from emergency response to retail planning.

By running spatial analyses, such as buffer zones or proximity checks, users can evaluate how different geographic elements relate to each other. For instance, GIS can determine the area within a 5 km radius of a fire station or highlight all schools located within a pollution-prone zone.

4.3. Urban Planning, Land Use & Disaster Management

4.3.1. Urban Planning & Land Use:

Geographic Information Systems (GIS) are transformative tools in the realm of urban planning and land use management. They enable city planners to analyze, visualize, and predict how land is used, thereby facilitating more informed and sustainable development decisions.

How City Planners Use GIS

Visualizing Existing Land Use Patterns :

Mapping Current Use: Planners can overlay land parcels with current zoning, infrastructure, residential areas, commercial zones, and green spaces.

Spatial Analysis: Identifying trends, such as clustering of commercial activities or gaps in public services.

Simulating and Predicting Urban Growth :

Growth Models: GIS supports simulations that project how cities may expand based on population trends, economic factors, and policy changes.

Scenarios Testing: Planners can visualize the effects of proposed developments or zoning changes before implementation, helping to avoid traffic congestion and overbuilt areas.

Infrastructure Planning :

Site Selection: GIS aids in determining optimal sites for new schools, hospitals, parks, or transit corridors by considering:

Population density

Proximity to existing services

Transportation networks

Environmental constraints (wetlands, floodplains, conservation areas)

Connectivity Assessment: Ensures new facilities are accessible and integrated within the broader city framework.

4.3.2 Disaster Management:

GIS is invaluable during natural disasters—it helps forecast risks, coordinate emergency response, and assess damage afterward. Layers such as elevation, rainfall, and river flow help predict flood-prone zones, while satellite data can track wildfires or landslides in real time.

Rescue teams use GIS to plan evacuation routes, identify shelters, and track resource distribution. After disasters, GIS maps assist in calculating affected areas, helping government and relief agencies respond more effectively and rebuild smarter.

4.4. Agriculture & Crop Monitoring

Modern agriculture uses GIS for what's called precision farming, which means tailoring farming techniques to specific areas of land based on conditions like soil type, moisture levels, and historical yield data.

GIS can help farmers identify which parts of their fields need more water, where pests are concentrated, or where to apply fertilizer. This saves resources, boosts productivity, and makes farming more environmentally friendly.

This approach enables farmers to::

Map field conditions: GIS helps create detailed soil and vegetation maps, revealing variability in crop health, soil fertility, and moisture levels across the field

Target resource application: Using these maps, farmers can apply water, fertilizers, and pesticides only where needed instead of blanket-treating the whole area, optimizing inputs, saving costs, and reducing environmental impact

Boost productivity and sustainability: By precisely targeting interventions, farmers can increase crop yields—sometimes by up to 30%—while minimizing waste and environmental harm

Identify problem areas: GIS can highlight spots with poor plant growth, pest hotspots, or nutrient deficiencies, allowing quick and specific remedial action

Monitor and plan efficiently: With features like time-series comparison and integration with satellite imagery, farmers can continuously monitor fields and adjust strategies as conditions change

Overall, GIS empowers farmers to use data-driven insights for more efficient, profitable, and environmentally friendly agriculture

4.5. Navigation & Routing

GIS powers nearly all navigation apps, from Google Maps to ride-sharing services. It constantly processes live traffic updates, road closures, and user feedback to recommend the fastest or most fuel-efficient routes.

Logistics and delivery services rely heavily on GIS to optimize routing, reduce travel time, and improve fuel efficiency. Even public transportation planning uses GIS to create better schedules and routes based on commuter demand.

GIS is the backbone of modern navigation and routing, powering everything from everyday apps to complex logistics operations.

Navigation Apps: Leading services like Google Maps rely on GIS to provide real-time, turn-by-turn navigation. They process live traffic conditions, road closures, and user-reported incidents to suggest the fastest or most fuel-efficient routes. Users benefit from up-to-date information such as traffic jams or detours and can plan journeys efficiently with tools for walking, driving, cycling, or public transit

Logistics & Delivery Optimization: Companies use GIS to optimize routes for delivery vehicles and service fleets, reducing travel time and maximizing fuel efficiency. GIS tools analyze road networks and dynamic conditions (like traffic or weather), enabling intelligent planning for multi-stop routes and efficient response to changing events on the road

Public Transportation Planning: City transit agencies utilize GIS to design schedules and routes that match commuter demand, analyzing data on population density, travel patterns, and service usage to improve coverage and efficiency. This results in smarter, more reliable public transport systems.

GIS enables real-time, data-driven decisions for routing and navigation in consumer apps, logistics, and public transportation, making travel faster, more efficient, and responsive to changing conditions.

First Previous Next Last

Topics :

4.1. Introduction

4.2. Create Smart Maps & Analyze Spatial Data

4.3. Urban Planning, Land Use & Disaster Management

4.4. Agriculture & Crop Monitoring

4.5. Navigation & Routing

4.3.1. Urban Planning & Land Use:

4.3.2 Disaster Management:

eBhuAdhyan

E-LEARNING FOR LAND LEADERS

Centre of Excellence

Welcome to Chapter 1 : Introduction to Geo-Referencing

Topics :

Welcome to Chapter 2 : Geo-referencing using Ground Control Points (GCPs)

Topics :

Welcome to Chapter 3 : Geo-referencing Using Image-to-Image

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Welcome to Chapter 4 : Cool Things You Can Do With GIS

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Welcome to Chapter 5 : How to Start with GIS ? (Even if You’re a Total Beginner)

5.2.1 Google Earth - The Visual Core of GIS:

5.2.2 QGIS:

Take a Free Online GIS Course – No Experience Needed!

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Welcome to Chapter 6 : Conclusion: GIS = Real World Superpower

That’s the power of spatial thinking.

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