Raster data with subdatasets has a data structure that allows the file format to contain multiple datasets in one parent file; this is also known as a multipage raster. Additionally, each of the subdatasets can consist of one band or multiple bands. Hierarchical data format (HDF) and National Imagery Transmission Format (NITF) both have the capacity to store multiple images (subdatasets) within one file. These subdatasets represent images taken in different bands or at different times and angles or photographs of objects.
HDF is a file format for storing multiobject data structures, such as raster images, binary tables, and multidimensional arrays. It is a method that is used to transfer graphic and numeric data between computers. There are many different types of HDF data models; ArcGIS is capable of reading HDF4 and HDF5 data that is based on a raster data model. Not all HDFs are subdataset files.
NITF is a collection of standards and specifications that allows interoperability in the dissemination of imagery and its metadata among various computer systems. These NITF standards and specifications were developed by the National Geospatial-Intelligence Agency (NGA). An NITF file can be an image accompanied by subimages, symbols, labels, text, and other information that relates to the image. Not all NITFs are subdataset files.
Viewing and working with these data formats in ArcGIS is slightly different than most other supported data formats, since they can consist of multiple datasets. When you add an HDF or NITF dataset in ArcMap, the Subdataset Selection dialog box appears and prompts you to select which subdatasets to use in the ArcMap session. In ArcCatalog, the NITF format will display all the subdatasets in the preview; however, the HDF format will only display the first subdataset in the preview. The Extract Subdataset tool allows you to create a new raster dataset with only the user-defined subdatasets. In the new raster dataset, each subdataset will appear as a band.
When adding this data to a mosaic dataset, only the first raster will be added. If you want to added other rasters within the dataset, use the Extract Subdataset tool to convert each raster to another format, such as TIFF.