Skip to main content

DEM DSM DTM

Digital Terrain Model (DTM)
Digital Surface Model (DSM)
Digital Elevation Model (DEM):

1. Digital Terrain Model (DTM):
   - A DTM represents the bare earth's topography, excluding any above-ground features like buildings, vegetation, or other structures.
   - It provides a digital representation of the ground's elevation, which is particularly useful for engineering, geology, and land surveying applications.
   - DTMs are typically created by removing all surface objects and structures from elevation data, leaving only the natural terrain.

2. Digital Surface Model (DSM):
   - A DSM represents the earth's surface, including both natural terrain and any above-ground objects such as buildings, trees, and infrastructure.
   - It provides a comprehensive view of the entire landscape, including all visible features.
   - DSMs are often used in applications like 3D modeling, urban planning, and environmental analysis, where a complete picture of the surface is required.

3. Digital Elevation Model (DEM):
   - A DEM is a general term that can refer to either a DTM or a DSM, depending on the context and the specific data it contains.
   - In some cases, people use "DEM" to describe any digital representation of elevation data, whether it includes only terrain (DTM) or both terrain and surface objects (DSM).
   - It's important to clarify whether a DEM is a DTM or a DSM when working with elevation data to ensure its suitability for a particular application.

In summary, these three models differ in the scope of data they represent. DTM focuses on the bare earth's topography, DSM includes all surface features, and DEM is a more general term that can refer to either DTM or DSM depending on the data's content and purpose.




Comments

Post a Comment

Popular posts from this blog

geostationary and sun-synchronous

Orbital characteristics of Remote sensing satellite geostationary and sun-synchronous  Orbits in Remote Sensing Orbit = the path a satellite follows around the Earth. The orbit determines what part of Earth the satellite can see , how often it revisits , and what applications it is good for . Remote sensing satellites mainly use two standard orbits : Geostationary Orbit (GEO) Sun-Synchronous Orbit (SSO)  Geostationary Satellites (GEO) Characteristics Altitude : ~35,786 km above the equator. Period : 24 hours → same as Earth's rotation. Orbit type : Circular, directly above the equator . Appears "stationary" over one fixed point on Earth. Concepts & Terminologies Geosynchronous = orbit period matches Earth's rotation (24h). Geostationary = special type of geosynchronous orbit directly above equator → looks fixed. Continuous coverage : Can monitor the same area all the time. Applications Weather...
Post a Comment
Read more

Disaster Management

1. Disaster Risk Analysis → Disaster Risk Reduction → Disaster Management Cycle Disaster Risk Analysis is the first step in managing disasters. It involves assessing potential hazards, identifying vulnerable populations, and estimating possible impacts. Once risks are identified, Disaster Risk Reduction (DRR) strategies come into play. DRR aims to reduce risk and enhance resilience through planning, infrastructure development, and policy enforcement. The Disaster Management Cycle then ensures a structured approach by dividing actions into pre-disaster, during-disaster, and post-disaster phases . Example Connection: Imagine a coastal city prone to cyclones: Risk Analysis identifies low-lying areas and weak infrastructure. Risk Reduction includes building seawalls, enforcing strict building codes, and training residents for emergency situations. The Disaster Management Cycle ensures ongoing preparedness, immediate response during a cyclone, and long-term recovery afterw...
Post a Comment
Read more

Linear Arrays Along-Track Scanners or Pushbroom Scanners

Multispectral Imaging Using Linear Arrays (Along-Track Scanners or Pushbroom Scanners) Multispectral Imaging: As previously defined, this involves capturing images using multiple sensors that are sensitive to different wavelengths of electromagnetic radiation. Linear Array of Detectors (A): This refers to a row of discrete detectors arranged in a straight line. Each detector is responsible for measuring the radiation within a specific wavelength band. Focal Plane (B): This is the plane where the image is formed by the lens system. It is the location where the detectors are placed to capture the focused image. Formed by Lens Systems (C): The lens system is responsible for collecting and focusing the incoming radiation onto the focal plane. It acts like a camera lens, creating a sharp image of the scene. Ground Resolution Cell (D): As previously defined, this is the smallest area on the ground that can be resolved by a remote sensing sensor. In the case of linear array scanne...
Post a Comment
Read more

Discrete Detectors and Scanning mirrors Across the track scanner Whisk broom scanner.

Multispectral Imaging Using Discrete Detectors and Scanning Mirrors (Across-Track Scanner or Whisk Broom Scanner) Multispectral Imaging:  This technique involves capturing images of the Earth's surface using multiple sensors that are sensitive to different wavelengths of electromagnetic radiation.  This allows for the identification of various features and materials based on their spectral signatures. Discrete Detectors:  These are individual sensors that are arranged in a linear or array configuration.  Each detector is responsible for measuring the radiation within a specific wavelength band. Scanning Mirrors:  These are optical components that are used to deflect the incoming radiation onto the discrete detectors.  By moving the mirrors,  the sensor can scan across the scene,  capturing data from different points. Across-Track Scanner or Whisk Broom Scanner:  This refers to the scanning mechanism where the mirror moves perpendicular to the direction of flight.  This allows for t...
Post a Comment
Read more

Disaster Risk

Disaster Risk 
Post a Comment
Read more