For those experienced in GIS, most are aware of the following formats. For those that are new to GIS, the primary data formats for “map layers” include:
- Vector – typically, points, lines, and polygon “feature classes” representing/modeling a point location (fire hydrant), line features (road/trail/pipeline), polygon (administrative boundary, project area, habitat, impacted area)
- Shapefile – ESRI created format. Been around for a long time, commonly used up to the file geodatabase feature class format. Has serious limitations (see below)
- File Geodatabase – still points, lines, polygon “feature classes.” Think of the file geodatabase as the container and the point, line, and polygon feature classes (and other formats) are stored within the file geodatabase. Rasters (images), and Triangulated Irregular Networks (TINs), stand alone tables (tables with no specific geographic features) are few other common data formats that can be stored in a file geodatabase
- Enterprise Geodatabase – similar to the file geodatabase, but the enterprise geodatabase lives in an “enterprise” relational database management system (RDBMS) such as SQL Server, Oracle, Postrgres (there are others, but these are the 3 most common
- Raster – image data (typically, aerial, satellite, UAV/drone) georeferenced to the Earth’s surface. Organized as bands, rows, and columns. Bands refers to the wavelengths of reflected light being captured on a remote sensing device (airplane, satellite, UAV camera), rows and columns refers to the organization of pixels (picture elements) which represent the specific entity that stores a value (typically a value representing the amount of reflected energy, but can also represent a land cover/land use type, elevation, temperature, precipitation, etc).
- File-based Raster – Typically, a TIF file, but other typical file extensions are: IMG – often referred to as an ERDAS Imagine file and JPG – this is a compressed image format sometimes used as a background image, provided the image is georeferenced to the ground. BMP, GIF, PNG typically are NOT used in GIS as a raster file format. These image file types often are used with photos (e.g. from a phone or tablet camera) or an icon image (e.g. a street sign, trail marker, etc).
- Raster Dataset – this format is often found within the file geodatabase or enterprise database and these images DO NOT have a file extension. One will see both a raster icon and the name “Raster Dataset” when browsing a file or enterprise geodatabase.
- LAS Dataset (aka Point Cloud Dataset) – LiDAR (Light Detection and Ranging) represents georeferenced point data containing latitude, longitude, and elevation generated from laser pulses, typically from aerial systems, but can also be generated from satellite or special UAV systems. The general format is called a point cloud, since billions of individual points look like “a cloud” that tends to look like a surface (think 3D) of objects on the ground and contain height and volume (think vertical depictions of fire hydrants, trees, cars, curbs, buildings, etc). Point cloud data can also be derived from special image processing routines called “photogrammetry” where the elevation value can be derived from overlapping aerial images.
- Triangular Irregular Network – TIN – this format models geographic surfaces derived from point or contour or other elevation source using a series of connected triangles. This format often is shown with its own specific icon when viewing this kind of data in Pro.
- Web Service Layers – these include map layers (and images) that are stored and used on the ESRI cloud and are used in web maps and web map applications. Often these layers are derived from file and enterprise geodatabase formats or from file-based or raster datasets. One can create point, line, and polygon web feature layers (you will see these referred to as feature layers or hosted feature layers) and the rasters will be referred to as raster datasets or image service layers.
Other GIS data/map layer formats do exist, but those mentioned above cover the vast majority of data types/model found in any GIS system.