Formosat-5

Long name Formosat-5
Short name FMS5
Sensor type Electro-optical
Platform Formosat-5
Key file name (use to open dataset) FS5_*.dim
Supported file name extensions .tif, .rpb, .jpg
Sections

Data product name and description
Distribution disk files
Returned data for supported format
References

Data product name and description

Formosat-5 is an Earth-observation satellite operated by the National Space Organization (NSPO) of Taiwan in a Sun-synchronous orbit (SSO) at a mean altitude of 720 kilometers. The satellite provides high-resolution 2-meter panchromatic (PAN) and 4-meter multispectral (MS) imagery with a swath width of 24 kilometers.

A follow-on mission of FormoSat-2, Formosat-5 is the first remote-sensing satellite developed indigenously by NSPO. An important objective for FormoSat-5 is to build up the domestic capability for the high-resolution, optical, remote-sensing instrument (RSI) by integrating NSPO with the Instrument Technology Research Center (ITRC) of the National Applied Research Laboratories (NARL). Both NSPO and ITRC belong to NARL, a nonprofit organization under the supervision of the National Science Council (NSC).

FORMOSAT-5 satellite includes the spacecraft bus, RSI, and advanced ionospheric probe (AIP). The spacecraft bus and RSI are self-reliantly developed by NSPO. The AIP, the scientific payload, is built by National Central University (NCU) in Taiwan.

The main characteristics of the instrument are as described in the following table.

Characteristic Description
Registration After ground processing
Pointing capability ± 45 degrees roll and pitch
Focal length 3600 millimeters
Pupil diameter 450 millimeters
Type Cassegrain with refractive corrector
Complementary metal-oxide-semiconductor (CMOS) sensor C468
Processing rate: 40 megapixels per second
Mass 138 kilograms
Power consumption 100 watts for orbit average
Image product PAN-only, MS-only, PAN + MS
Acquisition mode Recording (RECORD), direct data transmission (DDT)
Geo-accuracy of imagery:

#8226; With ground control points (GCP): 2 meter
#8226; Without GCPs: 390 meter

Information specific to the PAN and MS imagery is as described in the following table.

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)

Notes

PAN
450 - 700

2.0 2.0 x 2.0 (12-bit)

Integration time: 0.297 milliseconds
Compression ratio: 1.0,1.5
Signal-to-noise ratio (SNR): ≥ 92

MS
450 - 520 (Blue)
520 - 600 (Green)
630 - 690 (Red)
760 - 900 (NIR)

4.0 4.0 x 4.0 (12-bit)

Integration time: 0.594 milliseconds
Compression ratio: 3.75,7.5
Signal-to-noise ratio (SNR): ≥ 100

* Resolution is always nadir position unless noted otherwise.

Formosat-5 data is available in the following processing levels:
  • Level 1A (L1A)
  • Level 2 (L2TWD97) with TWD97 map-projection coordinate
  • Level 2 (L2UTM) with UTM map-projection coordinate
  • Level 2 (L2WGS84) with WGS84 coordinate
  • Level 4 (L4TWD97) with TWD97 map-projection coordinate
  • Level 4 (L4UTM) with UTM map-projection coordinate
  • Level 4 (L4WGS84) with WGS84 coordinate
Note: Only L1A and L4TWD97 are available and tested.
Processing level Horizontal accuracy (m) Description/notes
L1A N/A

Only Data Strip is available.
It includes ephemeris, attitudes, sensor configuration, calibration data, and so forth.

L4TWD97   This product does not have a rational functions math model.

Distribution disk files

A Formosat-5 data set is organized in a specific folder structure on disk. GDB uses this folder structure and the file names to identify the data product type.

Warning: To ensure the image data and auxiliary information are imported correctly, do not alter the folder structure or any file names prior to data ingestion.

You can open a Formosat-5 data set by selecting the FS2_*.dim file.

When opening a Formosat-5 data set, the files read by GDB are as described in the following table.

File name Format Required Contents/details
FS5_*.dim DIM Yes Key file name. Contains data-set metadata.
FS5_*.tif GeoTIFF Yes Image data.
FS5_*.rpb Text Optional Applicable only with L1A.
FS5_*cds.jpg Joint Photographic Experts Group Optional Thumbnail file.
FS5_*qls.jpg Joint Photographic Experts Group Optional Overview file.

File name convention

The file name convention of Formosat-5 data is as described in the following table, based on a sample file name of FS5_G031_MS_L1A_20171220_024019.tif.

File name segment Description
FS5_G031 Grid index
MS Spectrum type
L1A Processing level
20171220_024019 Date of acquisition (YYYYMMDD_HHMMSS)

Returned data for supported format

Formosat-5 data can be opened directly in its raw vendor format or imported into a PCIDSK (*.pix) file using the key file name FS5_*.dim). 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
L1A (PAN)

1 x [16U] Raster channel
1 x [BIN] Rational functions model
1 x [TEX] Product annotation
1 x [ORB] Orbit segment

N/A
L1A (MS)

4 x [16U] Raster channels
1 x [BIN] Rational functions model
1 x [TEX] Product annotation
1 x [ORB] Orbit segment

N/A
L4TWD97 (PAN)

1 x [16U] Raster channel
1 x [TEX] Product annotation
1 x [ORB] Orbit segment

N/A
L4TWD97 (MS)

4 x [16U] Raster channels
1 x [TEX] Product annotation
1 x [ORB] Orbit segment

N/A

References

For more information, visit: nspo.org

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