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.
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 you add your subdataset you have three options
- Add a single item from the subdataset to create a single-band raster dataset layer.
- Add multiple items from the subdataset to create multiple single-band raster dataset layers, contained in a group layer.
- Add multiple items from the subdataset to create a multiband (RGB) raster dataset layer (each item must fully overlap).
- In ArcMap, click the Add Data button button.
- Navigate to the location of the HDF or NITF file.
- Click the file and click Add.
The Subdataset Selection dialog box opens.
- Click a single subdataset to add. Optionally, press and hold the CTRL key to select more than one.
- If you choose more than one item, you can optionally check Add as RGB layer to add them as a single raster dataset layer.
- Optionally, check the Do Not Ask Again check box if you do not want the dialog box to appear again.
Choosing this option automatically loads the first subdataset for any HDF and all the subdatasets for any NITF that you add.
- Click OK.