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Techniques of Remote Sensing.

Remote sensing is detecting and monitoring an area’s physical characteristics by measuring its reflected and emitted radiation at a distance. The earth is scanned by satellites or high-flying aircraft in order to obtain information about it.

Two main types of remote sensing exist and are classified according to the source of signal they use to explore the object, active and passive.

Active remote sensing instruments operate with their own source of emission or light.

Passive remote sensing relies on the reflected emission to obtain information. Reflected sunlight is the most common source of radiation measured by passive sensors.


Passive sensors can only detect energy when naturally occurring energy is available. For all reflected energy, this can only take place during the time when the sun is illuminating the Earth. There is no reflected energy available from the sun at night. The energy that is naturally emitted (such as thermal infrared) can be detected day or night, as long as the energy is large enough to be recorded.

Active sensors, on the other hand, provide their own energy source for illumination. The sensor emits radiation which is directed toward the target to be investigated. The radiation reflected from that target is detected and measured by the sensor.

The advantages of active sensors include the ability to obtain measurements anytime, regardless of the time of day or season. Active sensors can be used for examining wavelengths that are not sufficiently provided by the sun, such as microwaves, or to better control the way a target is illuminated.

However, active systems require the generation of a relatively large amount of energy to illuminate targets adequately.

The sun provides a very convenient source of energy for remote sensing. The sun’s energy is either reflected, as it is for visible wavelengths, or absorbed and then re-emitted, as it is for thermal infrared wavelengths. Remote sensing systems which measure the energy that is naturally available are called passive sensors.

A random/common example is using a camera in sunlight. During a bright sunny day, enough sunlight illuminates the targets and then reflects toward the camera lens. The camera records the radiation provided. This can be described as remote sensing in passive mode.

On a cloudy day or inside a room, there is often not enough sunlight for the camera to record the targets adequately. So, it uses its own energy source – a flash – to illuminate the targets and record the radiation reflected from them. This can be described as an active mode of remote sensing.



Remote sensing and the environment

Remote Sensing is the process of detecting and monitoring the physical characteristics of an area by measuring its reflected and emitted radiation at a distance (typically from satellite or aircraft). Special cameras collect remotely sensed images, which help researchers “sense” things about the Earth.

The use of remote sensing (RS) makes it possible to provide reliable information on environmental conditions, properties of the spatial structure of natural-territorial complexes, their dynamics and helps in accumulation of data for the development of the system natural resources monitoring.

By utilizing GIS modeling tools, potential impacts can be predicted and included in the management and monitoring programs. GIS and remote sensing could be used in environmental monitoring for Land use / Land cover analysis, wetland assessment and ground water modeling, habitat mapping, disaster management etc.

Remote Sensing replaces slower, costly data collection on the ground, providing fast and repetitive coverage of extremely large areas for everyday applications, ranging from weather forecasts to reports on natural disasters or climate change.

Remote sensing and the environment


The applications of remote sensing include land-use mapping, weather forecasting, environmental study, natural hazards study, and resource exploration.

  • The information derived from remote sensing can be directly related to measuring important socio-economic impacts. Rates of land cover change and drought, for example, will strongly influence vegetation yield, which substantially impact upon human health and well-being.


  • It helps to create information base on land use, land cover distribution, urban change detection, monitoring urban growth and urban environmental impact assessment. Satellite images enable us to better understand some of the intrinsic components of urban ecosystems and the interactions within whole urban environment.


  • Most of the information used by soil scientists to map soil seriesis obtained by direct observation in the field. It is essential that subsurface soil profiles be examined and careful biological, chemical, and physical measurements be obtained within each soil horizon.

Larger areas can be sensed remotely in a very easy way and the whole data can be easily processed and analysed fast by using the computer and that data is utilised for various purposes. Data Collection is really very easy over a variety of scales and solutions.




Geographic Information Systems GIS is a tool mainly used to gather, analyse, and interpret data captured during the remote sensing process.

It is applicable in different sectors where it is used by professional analysts to analyse data for different uses.

Housing is one of the basic needs of humans along with food and water. A good shelter should protect the person in it from unfavourable weather conditions all year round.

Apart from natural disasters which occur occasionally, shelters should be able to withstand most conditions.

Even in cases of natural disasters, GIS has been known to help rescue efforts and help detect the best place to settle to prevent reoccurrences.

One of the main applications of GIS use in the housing sector has been in the area of dealing with environmental hazards such as floods, landslides, soil erosion, and drought. It is not possible to stop these events but GIS can be used to mitigate or decrease their impact



  • GIS aids effective land administration, providing the platform for structured housing and land management.


  • GIS can help individuals and businesses protect property rights, encourage open and competitive real estate markets, bring efficiencies in land administration (SDI, government, taxation, land consolidation etc)


  • GIS aids in Land Use Classification and planning.


  • GIS aids in the creation and management of Creation of address registers in partnership with local government areas, for easy analysis and upgrade of community database and mapping.


  • Besides mapping areas in real estate, GIS can also play an important role in spatial analysis and determination of the absolute location where houses need to be situated.


  • GIS Makes Performing Market Analysis Better: Market analysis is one of the most essential steps in housing. Research needed for each may differ in depth, but both require analyzing comparative sales in a given location. Prior to analysis, additional research is conducted on comparable properties recently developed in the subject property’s area.


  • GIS enables tasks including site selection, land suitability analysis, land use and transport modelling, the identification of planning action areas, and impact assessments.



Turning Historical Map into 3D Map

Turning Historical Map into 3D Map

Turning Historical Map into 3D Map

Software Used:

  • ArcGIS
  • QGIS
  • Blender

Source for the Old Maps and Digital Elevation Model The first step in the process is to find an old digital vintage map of an area with some relief and a decent image resolution

Turning Historical Map into 3D Map    Turning Historical Map into 3D Map

Historical maps are contemporary maps from a specific point in time, showing land use and settlement patterns as recorded at that point. Historians use historical maps for several purposes:

As tools for reconstructing the past, to the extent that maps provide records of features, landscapes, cities, and places that may not exist anymore or that exist but have been transformed

Historical maps can be challenging to read, hence their recent transformation into three-dimensional views. 3D Mapping technology is used to profile objects and create a 3-dimensional view that can be mapped onto the real world.

As the name suggests, it is a 3-dimensional representation of objects meaning it maps objects on the x, y, and z-axis. 3D mapping represents elevation and location, making it helpful in developing scale models of features in buildings or the Earth.

This added layer or rather added dimension helps visualize data and has increased the number of applications and use cases for Geodata.

The Following paragraphs give a detailed explanation of how to turn your historical map into 3D.

Software Used:

  • ArcGIS
  • QGIS
  • Blender

Source for the Old Maps and Digital Elevation Model

The first step in the process is to find an old digital vintage map of an area with some relief and a decent image resolution or if you have an old paper map of an area, you can scan and use it.

Tip: Look at the contour lines in the map and take note of the height and how packed or spaced the contour lines are – tightly packed contours have higher relief than spaced contours.

A map of flat lands will not produce the beautiful result we want, we need some mountainous terrain that will make the 3D effect pop up. A good source to get old vintage maps is the USGS TopoView which serves a large collection of georeferenced topographic maps covering the US.

There are dozens of other sources of old maps on the internet. Download the DEM of the area from the USGS Earth Explorer.

Georeferencing the Map

This is the first and most important step – we would use the ArcGIS software in georeferencing the map using the coordinates on the map to register the four (4) points around the map. It is important as the concept to create the 3D map is overlaying the old map on the DEM (Relief)/Hillshade.

After we have successfully georeferenced the map. We then create a polygon around the border of the map area. This will be used to clip the DEM to the map extent.

We’ll then create an outer boundary for the paper boundary of the map.


We’ll import the DEM and the shapefile into QGIS and use the create new raster tool ‘r.mapcalc.simple’ this will create a new raster from the DEM using the paper boundary polygon. Then we use the ‘r.null’ tool to calculate the null values. After creating the raster we’ll save it as a render format (RGB) ‘.tif ‘


We suggest watching a few videos on how to navigate a blender before moving on to the next steps. If you haven’t installed Blender yet, it can be downloaded Here.

Turning Historical Map into 3D Map

We hope the above steps will help you get the hang of using the ArcGis And QGIS Software for turning maps into 3D. You can also experiment with other kinds of maps and let us know how the transformation worked.

Turning Historical Map into 3D Map


Role of GIS in Regional and Geographical Planning and Construction

Role of GIS in Regional and Geographical Planning and Construction

Role of GIS in Regional and Geographical Planning and Construction

The capacity to better understand the current needs of a city, and then design to fulfill those needs is one of the important uses of GIS in the city and regional planning and designing. By processing geospatial data from satellite imaging, aerial photography, and remote sensors, GIS users gain a detailed perspective on land and infrastructure.

Spatial data points the way to improving quality of life and building sustainable communities, while geographic information science professionals use spatial thinking to transform that data into actionable insight and solutions.

In analyzing the future population growth of an area, a geographer would study the regional environment. This environment offers certain resources, which can be compared with similar environments and resources that the geographer knows in other parts of the world.

These powerful tools help planners understand the needs of densely populated areas, but they also adapt to examining smaller towns and even informal settlements. The ability to run a variety of queries and analytics on GIS data means experts can evaluate how new construction will fit in with existing infrastructure and meet regulatory demands. Users may spot opportunities for improved resource use, identifying the best locations to harvest solar, wind, or geothermal energy.


Role of GIS in Regional and Geographical Planning and Construction

GIS technology empowers urban planners with enhanced visibility into data. They monitor fluctuations over time, evaluate the feasibility of proposed projects and predict their effects on the environment. GIS software can also show all relevant stakeholders exactly what the changes on the ground will look like to help them make better decisions. For example, GIS software may generate visualizations of an area’s current environmental conditions and allow users to draw comparisons between the anticipated results of proposed development plans.

Urban planners in both the public and private sectors employ data-driven methods to address a wide array of issues that have long-term implications for communities and the surrounding landscape. 

Some of these methods include 

  • Review and analysis of plans for development.
  • Checks on regulatory compliance.
  • Review of environmental impact.
  • Preservation of historic sites.
  • Regional planning beyond the borders of a city or town.
  • Mapping the delivery of utilities and planning for service interruptions.


By performing land use analyses, planners can guide new developments to areas that are less prone to damage from natural disasters. Synthesizing geographic information with financial data might lead to revitalizing an urban area in need of new businesses. This can help the establishment of shopping malls and marts to provide erstwhile unavailable services and goods.


For example, GIS software can help a City’s Planning Committee to collaborate with other stakeholders in the stages of the efforts to redevelop sections of the highway. 


GIS offers the means to synthesize information from a diverse set of sources, model the outcomes of multiple courses of action, and share data among the Public Works and other departments. 


Experts from many different disciplines may find common ground and create actionable plans for making services and amenities more accessible and also make travel easier for the inhabitants of areas in need of better housing and construction planning. 


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