Orthophoto

Aerial photograph geometrically corrected to be map-accurate

Orthophoto

An orthophoto, also known as an orthophotograph, is an aerial photograph that has been geometrically corrected, or "orthorectified," so that the scale is uniform. Unlike an uncorrected aerial photograph, an orthophoto can be used to measure true distances, as it is an accurate representation of the Earth's surface, having been adjusted for topographic relief, lens distortion, and camera tilt.

Orthophoto vs. Perspective Image

Creation Process

The creation of an orthophoto involves several steps:

Aerial Photography

The process begins with the capture of aerial images using a camera mounted on an aircraft. These images are taken from multiple angles to ensure comprehensive coverage of the area.

Geometric Correction

The raw images are then processed to correct for distortions caused by the camera lens, the angle of the camera, and the topography of the land. This process is known as orthorectification.

Digital Elevation Model (DEM)

A Digital Elevation Model is used to account for variations in terrain. The DEM provides the necessary data to adjust the image so that it accurately reflects the Earth's surface.

Mosaicking

Multiple orthophotos are often combined to create a seamless image of a larger area. This process is known as mosaicking.

Orthophoto of Città Alta, Rocca

Applications

Orthophotos are used in a variety of fields due to their accuracy and detail:

Urban Planning

In urban planning, orthophotos provide a detailed and accurate base map for planning and development.

Environmental Studies

They are used in environmental studies to monitor changes in land use, vegetation, and water bodies over time.

Agriculture

In precision agriculture, orthophotos help in assessing crop health and planning irrigation systems.

Disaster Management

Orthophotos are crucial in disaster management for assessing damage and planning recovery efforts.

Aerial Orthophoto

Advantages

Orthophotos offer several advantages over traditional maps and photographs:

• Accuracy: They provide a true-to-scale representation of the Earth's surface.
• Detail: High-resolution orthophotos offer detailed imagery that can reveal features not visible on traditional maps.
• Versatility: They can be used in conjunction with other geographic information system (GIS) data for enhanced analysis.

Limitations

Despite their advantages, orthophotos have some limitations:

• Cost: The process of creating orthophotos can be expensive due to the need for specialized equipment and software.
• Time: Producing orthophotos is time-consuming, especially for large areas.

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Aerial True Orthophoto

Related Pages

• Aerial photography
• Geographic information system
• Digital Elevation Model
• Cartography

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Orthophotomap

See Also

• Remote sensing
• Topographic map
• Photogrammetry

Orthophotomap of Asturias

External Links

• [Orthophoto resources at USGS]
• [Orthophoto applications in urban planning]