Gaofen 4

Long name	Gaofen 4
Short name	GF4
Sensor type	Electro-Optical
Platform	GF4
Key file name (use to open dataset)	GF4_IRS_.xml, GF4_PMS_.xml
Supported file name extensions	.xml, .tiff, .rpb, .jpg
Sections	Data product name and description Distribution disk files Returned data for supported format References

Data product name and description

Gaofen 4 (GF4) is a geostationary Earth-observation satellite in the Gaofen series of Chinese civilian remote-sensing satellites.

GF4 features an visible-light and infrared-staring optical imager with a common optical system. The ground resolution for the visible-light imager is 50 meters and 400 meters for the infrared payload.

Note: The information provided herein is based on the data distributor's documentation cited under References.

Spectral bands: Spectral range (nm)	Spatial resolution (m)* (spectral resolution)	Maximum image dimensions (Across track x along track, km)	Swath width (km)	Notes
PAN (panchromatic): 450 - 900	50	N/A	400	Visible light, near infrared (VNIR)
MS (multispectral) MS1 (blue): 450 - 520 MS2 (green): 520 - 600 MS3 (red): 630 - 690 MS4 (near infrared): 760 - 900	50	N/A	400	Visible light, near infrared (VNIR)
Thermal	3500 - 4100	N/A	400	Medium-wave infrared (MWIR)

* Resolution is always nadir position unless noted otherwise.

GF4 data is available in the following processing levels:

Level 1A

Processing level	Horizontal accuracy (m)	Description/notes
1A	N/A	N/A

Distribution disk files

You can open a GF4 data set by selecting the GF4 *.xml file.

Warning: Data sets for this sensor are organized in a specific folder structure on disk. GDB uses this structure and the file names to identify the data product type. Do not alter the folder structure or any file names prior to data ingestion to ensure the image data and auxiliary information are imported correctly.

When opening a GF4 data set, the files read by GDB are as described in the following table.

File name	Format	Required	Contents/details
GF4_IRS_.xml GF4_PMS_.xml	Extensible Markup Language	Yes	Key file name, contains metadata of data set.
GF4_IRS_.tiff GF4_PMS_.tiff	GeoTIFF	Yes	Image data.
GF4_IRS_.rpb GF4_PMS_.rpb	Text	Yes	RPC data.
_GF4_IRS__thumb.jpg GF4_PMS_*_thumb.jpg	Joint Photographic Experts Group	Optional	Thumbnail files.

Returned data for supported format

GF4 data can be opened directly in its raw vendor format or imported into a PCIDSK (*.pix) file using the key file name (GF4_IRS_*.xml or GF4_PMS_*.xml). For optimal processing, use the PCIDSK format.

The following table describes the data structure after it is opened by GDB.

Data product	Data returned	Details
1A (PAN) (MS)	5 x [16U] raster channels 1 x [TEX] product annotation 1 x [ORB] orbit segment 1 x [BIN] binaries	The five raster channels include one panchromatic channel and four multispectral channels. The binaries [BIN] segment is RPC data.
1A (Thermal)	1 x [16U] raster channel 1 x [TEX] product annotation 1 x [ORB] orbit segment 1 x [BIN] binaries segment	The binaries [BIN] segment is RPC data.

References

For more information, visit: cresda.com