ArcGIS uses three ways to organize, store, and manage your raster data (raster data models). These structures, and the icon that represents each of them, are:
- The raster dataset:
- The mosaic dataset:
- The raster catalog:
Most imagery and raster data (such as an orthophoto or DEM) is provided as a raster dataset. The term, raster dataset, refers to any raster data model that is stored on disk or in a geodatabase. It's the most basic raster data storage model in which the others are built upon—both mosaic dataset and raster catalogs manage raster datasets. It's also the output from many geoprocessing tools that process raster data.
A raster dataset is any valid raster format organized into one or more bands. Each band consists of an array of pixels (cells), and each pixel has a value. A raster dataset has at least one band. More than one raster dataset can be spatially appended (mosaicked) together into a larger, single, continuous raster dataset.
Raster datasets can be stored in many formats, including TIFF, JPEG 2000, Esri Grid, and MrSid.
Raster datasets are represented with the icon.
Raster dataset overview
A mosaic dataset is a collection of raster datasets (images) stored as a catalog and viewed or accessed as a single mosaicked image or individual images (rasters). These collections can be extremely large, both in total file size and number of raster datasets. The raster data is added according to its raster type—which identifies metadata, such as georeferencing, acquisition date, and sensor type, along with a raster format. The raster datasets in a mosaic dataset can remain in their native format on disk or, if required, be loaded into the geodatabase. The metadata can be managed within the raster record as well as attributes in the attribute table. Storing metadata as attributes enables parameters such as sensor orientation data to be managed easily and allows fast queries to enable selections.
The raster data in a mosaic dataset does not have to be adjoining or overlapping but can exist as unconnected, discontinuous datasets. For example, you can have images that completely cover an area or you can have many strips of images that may not join together to form a continuous image (such as along pipelines).
The data can even be completely or partially overlapping but be captured over different dates. The mosaic dataset is an ideal dataset for storing temporal data. You can query the mosaic dataset for the images you need based on time or dates and use a mosaic method to display the mosaicked image according to a time or date attribute.
Mosaic datasets are represented with the icon.
Mosaic dataset overview
A raster catalog is a collection of raster datasets defined in a table format in which each record represents an individual raster dataset in the catalog. A raster catalog can be large and contain thousands of images. A raster catalog is typically used to display adjacent, fully overlapping, or partially overlapping raster datasets without having to mosaic them into one large raster dataset.
Raster catalogs are represented with the icon.
Raster catalog overview