Glossary
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Bare Earth Project
A bare earth project refers to a specific type of geospatial data processing or analysis focused on creating a representation of the Earth’s surface without any vegetation or man-made structures. The aim is to derive a digital model or elevation dataset that accurately represents the topography of the bare ground surface.
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Contour Map
A contour map, also known as a contour model or contour plot, is a representation of the three-dimensional shape and elevation of a land surface or terrain in a two-dimensional format. It uses contour lines, which are continuous curves that connect points of equal elevation above a reference level, typically sea level, with each line representing a specific elevation interval or contour interval to depict the variation in elevation across a specific geographic area.
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Drone
A drone, also known as an unmanned aerial vehicle (UAV), is an aircraft that is operated remotely or autonomously without a human pilot on board. Drones are typically equipped with various sensors, cameras, and other technology to perform a wide range of tasks, including aerial photography and videography, data collection, surveillance, delivery, and more.
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Earthworks
Earthworks refer to the engineering and construction activities involving the manipulation, movement, or excavation of large quantities of soil, rock, or other materials on the Earth’s surface. It typically involves shaping the topography of the land to prepare it for various purposes, such as building foundations, road construction, land development, or creating embankments for infrastructure projects. Earthworks play a fundamental role in transforming the natural landscape to meet the specific requirements for infrastructure development, land reclamation, mining operations, and various construction projects.
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FAA Part 107
FAA Part 107 refers to the regulations established by the Federal Aviation Administration (FAA) in the United States for the operation of small, unmanned aircraft systems (UAS) for commercial purposes. These regulations outline the rules and requirements that drone operators must follow to ensure safe and responsible operation. Under Part 107, drone operators must obtain a Remote Pilot Certificate by passing a knowledge test administered by the FAA. This certification demonstrates the operator’s understanding of aviation regulations, airspace restrictions, and safe operating practices. The certificate is valid for two years and can be renewed by passing a recurrent knowledge test.
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Ground Control Points
A Ground Control Point (GCP) is a specific and identifiable point on the Earth’s surface with known coordinates used as a reference in geospatial data collection and mapping and are typically physical markers positioned on the ground using high-accuracy surveying equipment like Global Navigation Satellite Systems (GNSS) that can be easily identified in the collected data. During data collection, the GCPs are identified and captured in the imagery or other geospatial datasets by matching their locations with their known coordinates. By referencing the GCPs, the collected data can be aligned with a geospatial coordinate system, correcting for distortions, scale variations, and positional errors that may exist in the raw data. The use of GCPs is crucial in achieving accurate and reliable geospatial data products, such as orthorectified imagery (orthomosaics), digital elevation models (DSMs and DTMs), or topographic maps.
GNSS Tripod on a Ground Control Point on a Construction Site
Ground Sampling Distance (GSD)
Ground Sampling Distance (GSD) refers to the physical size of one pixel in an image, typically taken by an airborne or satellite sensor, when it is projected onto the Earth’s surface. It represents the spatial resolution or level of detail captured by the sensor. GSD is usually expressed in terms of the distance on the ground that each pixel represents, such as meters per pixel or centimeters per pixel. GSD is influenced by various factors, including the altitude of the sensor, the focal length of the camera lens, and the sensor’s pixel size. It is an important consideration in remote sensing applications, such as aerial photography, satellite imaging, and geographic information systems (GIS), as it directly affects the accuracy and level of information that can be extracted from the imagery.
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Lidar
Lidar, an acronym for “Light Detection and Ranging,” is a remote sensing technology that measures distances and generates detailed three-dimensional representations of the Earth’s surface or objects using laser light. It is a surveying method that involves sending laser pulses from a sensor and measuring the time it takes for the light to reflect back after hitting a target. Lidar systems can capture precise elevation data, generate high-resolution point clouds, and create accurate digital terrain models.
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Nadir Images
A nadir image refers to an aerial (drone or satellite) image taken directly downward from the camera’s perspective, capturing a view of the Earth’s surface vertically beneath the sensor. In simple terms, it is an image captured from a 90 degree straight-down or overhead perspective.
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Oblique Images
An oblique image refers to an aerial or satellite image captured with an angled perspective, rather than a direct downward view. Unlike nadir images that capture a vertical view, oblique images are taken at an angle, usually from the side or at an inclined angle. By capturing oblique images, drone operators or satellite systems can offer a richer and more detailed visual dataset that complements the traditional nadir imagery.
Orthomosaic
An orthomosaic is a type of high-resolution aerial image that has been geometrically corrected so that it is free of distortion and has a uniform scale. It is created by stitching together multiple overlapping aerial photographs of a particular area, and then using specialized software to correct the perspective distortions and create a single, seamless image. Orthomosaics are often used in mapping and surveying applications, as they provide a detailed and accurate view of the terrain and features of the land. They can be used to create detailed maps, 3D models, and other types of visualizations, and can be especially useful in areas where traditional ground-based surveys are difficult or impractical.
Orthomosaic of 1582 Images Covering 200 Acres
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Photogrammetry
Photogrammetry is the science and technology of obtaining accurate measurements and information about the physical world using photographs or other forms of imaging. Photogrammetry is commonly used in industries such as surveying, construction, engineering, and architecture. A series of overlapping photographs are taken of the object or area from multiple angles using a camera or drone to create highly detailed and accurate 3D models of buildings, terrain, and other objects, which can then be used for analysis, design, and planning purposes. It involves analyzing photographs of an object or area from multiple angles and using algorithms to extract three-dimensional data and create detailed models and maps.
Point cloud
A point cloud is a set of data points in three-dimensional space that collectively represent the surface of an object or environment. Each data point, often referred to as a “point,” consists of X, Y, and Z coordinates, representing its position in the three dimensions of space. In addition to the spatial information, point clouds may also include other attributes associated with each point, such as color, intensity, or classification. Point clouds are typically generated using various sensing technologies, such as LiDAR (Light Detection and Ranging) scanners, laser scanners, or photogrammetry techniques. They provide highly detailed and accurate representations of objects and environments, allowing for measurements, analysis, visualization, and modeling and are used in various fields including surveying, mapping, architecture, engineering, and construction.
Point Cloud Example
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TIN
A TIN (Triangulated Irregular Network) file is a digital representation of a terrain surface. It is a vector-based data format that uses triangular elements to represent the elevation values of a terrain. In a TIN file, the terrain surface is divided into a series of non-overlapping triangles, where each triangle has three vertices (X, Y, and Z) and contains information about the elevation at those vertices. TIN files are commonly used in geographic information systems (GIS), surveying, and civil engineering applications. They are created by interpolating elevation data from various sources such as topographic surveys, LiDAR data, or satellite imagery. The resulting TIN file provides a detailed and accurate representation of the terrain surface, including its shape, slope, and elevation.
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Unmanned Aerial Vehicle (UAV)
Unmanned Aerial Vehicle (UAV), also commonly known as a drone, is an aircraft that does not require a human pilot onboard to fly. Instead, UAVs are typically controlled remotely from the ground or can be programmed to fly autonomously using pre-defined waypoints. They are used in a variety of applications, including aerial photography and videography, surveying and mapping, inspection of infrastructure, agriculture and forestry, search and rescue, and military and defense. They are more cost-effective than traditional aerial surveys or inspections, as they can cover large and difficult or dangerous areas for humans to reach quickly and efficiently.
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