Band aliases

Aliases supplement the organization of the attributes you calculate. With attributes calculated from image layers, corresponding fields are created in the attribute table of segments. To distinguish among the various attributes, the field name is appended with the relevant layer identifier. By using aliases, you can better manage and interpret the information in the attribute table, which you can view in Attribute Manager.

During attribute calculation, the metadata is analyzed for identification of various band names and short names based on the sensor and wavelength range.

Aliases are generated based on the GDB-provided channel-metadata tag, if it is present. With optical data, aliases are generated from the BandDescription tag and, with SAR data, from the Polorization tag. If the metadata is found, a generic short name, such as B01, B02, B03, and so on is applied as an alias. You can, however, modify the aliases to suit.

The following table shows an example of the channel-level metadata tags and aliases for a sample optical image, LC08_L1TP_018026_20160925_20170221.pix.

Table 1. Aliases for sample optical image
Input channel	LC08_L1TP_018026_20160925_20170221	Channel-metadata tag BandDescription	Alias
1	Landsat-8 Coastal Aerosol (0.435 - 0.451 um)	Coastal Aerosol	Aero
2	Landsat-8 Blue (0.452 - 0.512 um)	Blue	Bl
3	Landsat-8 Green (0.533 - 0.590 um)	Green	Gr
4	Landsat-8 Red (0.636 - 0.673 um)	Red	Red
5	Landsat-8 Near Infrared (0.851 - 0.879 um)	Near Infrared	NIR
6	Landsat-8 SWIR 1 (1.566 - 1.651 um)	SWIR 1	S1
7	Landsat-8 SWIR 2 (2.107 - 2.294 um)	SWIR 2	S2
8	Landsat-8 Cirrus (1.363 - 1.384 um)	Cirrus	Cir

Aliases with SAR data

The following table shows an example of the channel-level metadata tags and aliases for a sample SAR image, RS2_ FQ18_20090818_HH_VV_HV_VH_SLC.pix.

Table 2. Aliases for sample SAR image
Input channel	RS2_ FQ18_20090818_HH_VV_HV_VH_SLC	Channel-metadata tag Polarization	Alias
1	RADARSAT-2 HH Sigma Nought Complex	HH	HH0818
2	RADARSAT-2 HV Sigma Nought Complex	HV	VV0818
3	RADARSAT-2 VH Sigma Nought Complex	VH	VH0818
4	RADARSAT-2 VV Sigma Nought Complex	VV	VV0818

Note: If necessary, you can use the same segmentation vector layer to run attribute calculation on several images. If any of the images already have aliases and attributes matching the ones defined herein, they will be overwritten.