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23 guides on Raster.
What is LiDAR Data? Point Clouds, USGS 3DEP, Uses
LiDAR data is the set of 3D points produced by a laser scanner that times the return of each pulse to measure distance. Each point has x, y, z coordinates plus intensity and a classification such as ground, building, or vegetation. Airborne LiDAR data maps terrain and structures at centimeter to decimeter accuracy. What LiDAR […]
What is Landsat? Satellites, Bands, Data Access
Landsat is the joint USGS and NASA satellite program that has imaged the Earth’s land surface continuously since 1972, the longest such record in existence. Landsat 8 and Landsat 9 currently deliver 30 m multispectral and 100 m thermal imagery every 8 days combined. All Landsat data is free and open. What Landsat is Landsat […]
What is Hyperspectral Imaging? vs Multispectral
Hyperspectral imaging produces imagery that records a continuous spectrum for every pixel, typically 100 to 300 narrow bands 5 to 10 nanometers wide across visible, near-infrared, and shortwave infrared light. Multispectral imagery records 3 to 15 broad bands. The extra spectral detail lets analysts identify minerals, crops, plastics, and gases by their reflectance signature. What […]
What is the HRRR Model? NOAA Rapid Refresh Forecast
The HRRR model, NOAA’s High-Resolution Rapid Refresh, is a weather forecast model that runs every hour on a 3 km grid over the contiguous United States, with an Alaska domain every three hours. Each run forecasts 18 hours ahead, extended to 48 hours four times a day. HRRR is the highest-resolution operational forecast NOAA publishes. […]
What is a GeoTIFF? Format, Tags, and COG
A GeoTIFF is a TIFF image file that carries georeferencing metadata in standardized tags, so each pixel maps to a coordinate on Earth. The tags record the coordinate reference system, the pixel size, and the position of the grid origin. A Cloud Optimized GeoTIFF (COG) arranges the same file so clients can read parts of […]
What is Geospatial AI? Models and Agents
Geospatial AI, also called spatial AI or GeoAI, is the application of machine learning and AI agents to spatial data: satellite and aerial imagery, maps, elevation, and location records. It covers models that detect objects and change in imagery, models that predict values across space, and agents that write and run spatial analysis from natural […]
What is a Flood Risk Map? Zones and Depth Grids
A flood risk map shows where flooding is likely, how deep the water would be, and how often it is expected. The flood risk data behind it comes as regulatory flood zones, such as FEMA’s Special Flood Hazard Area, and as modeled depth grids for return periods like the 100-year and 500-year flood. What flood […]
What is Earth Observation Data? Types, Sources
Earth observation data is the imagery and measurements of the Earth’s surface, oceans, and atmosphere collected by satellites, aircraft, and drones. It includes optical and radar imagery, elevation, land cover, sea surface temperature, and atmospheric gases, delivered as georeferenced rasters with a timestamp. Open programs such as Copernicus and Landsat supply most of it free. […]
What is a Digital Elevation Model? DEM, DTM, DSM
A digital elevation model (DEM) is a raster in which every cell holds the height of the ground at that location, on a regular grid with a known cell size and vertical datum. A digital terrain model (DTM) records bare earth; a digital surface model (DSM) includes buildings and trees. DEMs underpin flood, slope, and […]
What is Catastrophe Modeling? Cat Models, AAL
Catastrophe modeling, or cat modeling, is the practice of estimating the financial losses a portfolio of insured properties would suffer from low-probability, high-severity events such as hurricanes, floods, earthquakes, and wildfires. A cat model is a stochastic model: it simulates thousands of possible events, applies each to the exposure at every location, and produces a […]
What is Change Detection in Satellite Imagery?
Change detection in remote sensing is the process of comparing two or more images of the same area, captured at different times, to identify where and how the surface has changed. It ranges from subtracting one raster from another to running a neural network over an image stack. The output is a map of change, […]
