GCOM-C SGLI
Map projection & GeoTIFF conversion
Tool

User’s Manual
Version 1.2

Oct. 2023
JAXA
GCOM-C projectUser’s Manual
Change Records (1/1)
Ver.

Rev.

Date

1.0

-

Jul. 2021

1.0

A

Jul. 2021

Page

Contents
First edition2

Added a note about the geolocation-shift ofhalf pixels

1.1-

Mar. 2022

4-5

Added options of -a, -n, -z, and -c

8

Added definition of the filename for option -c

9Changed TIFF tag settings for option –a, -n,-z and -c

11

Added Scene/Image start/end time in the
Global_attributes

1.2-

Nov. 2022

5

Changed the description of the option -c

A

Oct. 2023

2

Added a note about the resampling option forL2-tiles in section 4

Contents
1． Introduction ........................................................................................ 1
2． System Requirements ....................................................................... 1
3． Input Products / Available Datasets ................................................. 1
3.1 L1B scene/half-path products ...............................................................................1
3.2 L2 scene products ..................................................................................................2
3.3 L2 tile products .......................................................................................................2

4． Operation ............................................................................................ 2
5． Output Files ........................................................................................ 7
5.1 File naming ..............................................................................................................7
5.2 GeoTIFF tags/keys ..................................................................................................9
5.3 XML ancillary file ................................................................................................... 11

6． License information ......................................................................... 12
7． Appendix .......................................................................................... 13
7.1 The map projection for imageries in SGLI/HDF products .................................13

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1． Introduction
This user’s manual explains how to use the “Map projection and GeoTIFF conversion
tool for GCOM-C/SGLI HDF5 products”. The tool is used to convert the imageries in
HDF5 files of SGLI products into the generic GeoTIFF files through map projections ofgeodetic latitude/longitude or polar stereographic coordinates. The type of tool is CUI(Character User Interface) so that users can install it into their own system or scripts
for mass processing.

2． System Requirements
Hardware Requirements
・CPUIntel Xeon/Core-i7 or higher

・Memory

1GByte or higher.

Operating Systems
・Linux

Kernel 2.6 or higher (64bit)
The operation test has been done on RHEL7/CentOS7.

・Windows

Windows 10 (64bit)

3． Input Products / Available Datasets
Available input SGLI HDF5 products for this tool are L1B scenes/half-paths, L2-scenes,and L2-tiles.

3.1

L1B scene/half-path products

Available datasets in the L1B scene/half-path products of three sensors (VNR, IRS,
POL) are as follows:
Geometry_data/
Obs_time_*, Sensor_*, Solar_*Image_data/
Lt_*, Land_water_flag, QA_flag
Whole data are projected for the scenes of VNR and IRS, whereas a user specified
range of latitudes is projected for the half-path of POL.
The data including the tilt-driving (the change of tilt-angles) are available for POL,
though only the data in the pre- and post-driving are projected while the data during
the driving is not projected.

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3.2

L2 scene products

Available datasets in the four L2-scene products (NWLR, IWPR, SST, OKID) are as
follows:
Geometry_data/
Sensor_*, Solar_*,Image_data/
NWLR_*, PAR, QA_flag, TAUA_*, CDOM, CHLA, TSM, SST,
Cloud_probability, OKID

3.3

L2 tile products

All the datasets in the L2-tile products that have the size of 4800 x 4800 or 1200 x 1200
at the data-type of 8bits-unsigned or 16bits-signed/unsigned integer in the groups of
Image_data or Geometry_data are available. The frame of the output imagery isdetermined from the range of valid pixels on the dataset. No file is output if the specified
dataset has no valid pixels.
The details of the datasets in the L2-tile products can be found at:https://suzaku.eorc.jaxa.jp/GCOM_C/data/product_std.html
Note that this tool do not correct the geolocation-shift of half pixels included in L2 tile
products of until version 2003. The details of the geolocation-shift of half pixels can befound at:https://shikisai.jaxa.jp/faq/faq0086.html

4． Operation
Put the downloaded .exe file at any folder/directory in your file system. No installationis required. Run the .exe file at a command prompt (a terminal for Linux).
> SGLI_geo_map_linux(win).exe [hdf_filename(*.h5)] [OPTIONS]
Note:When the L2-tiles are processed with the resampling option of BL as the default, thepixels on the edges of the tiles will possibly be invalid. It may cause gaps in the tile
boundaries if the output imageries on neighboring tiles are mosaicked. To prevent thegaps, select NN for the resampling option.

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OPTIONS:
Option&Parameter

Description
Set the target dataset at DATASET (ex: Image_data/Lt_VN01).
This is mandatory for L2-scene or -tile products, whereas it is-d DATASET

optional for L1B products. Process all the image datasets(Image_data/Lt_*) for the L1B products when this was not
specified.

-o OUTPUTDIR

Set a directory for output files to OUTPUTDIR. If this was not
specified, the tool outputs files to a current directory.
Set the map projection to Polar-Stereo (PS). It is not applicable-pfor scenes over the equator. The default is GeodeticLatitude/Longitude.
Set the pixel spacing to SPACING. The unit is arc-sec forGeodetic-Latitude/longitude coordinates, while it is meter for
PS coordinates. The defaults are as follows:-s SPACING

Mode:

G-Lat/Lon

PS

Q(250m):7.5 arc-sec

250m

H(500m):15 arc-sec

500m

K(1km):

30 arc-sec

1km

The applicable ranges are 7.5~180 arc-sec for GeodeticLatitude/Longitude and 250m~6km for PS. For the IRS/L1B
without –d option, specify the spacing for the data of 1kmmode so that the data of 250m-mode and of 500m-mode areprojected with the spacing of its 1/4 and 1/2 respectively.
Select the resampling method from NN, BL, or CC with anumber specified at RESAMPLING. The definitions of numbers
are as follows:-r RESAMPLING

0 = NN, 1 = BL, and 2 = CC.
The default is NN for flag datasets and is BL for others. SelectNN for L2-tile products to prevent the gaps on the edge of tiles
especially if the output imageries on neighboring tiles will bemosaicked.

-m

Mask the stray-light correction flag (MSB2bits) in DN value of
TOA radiance (Lt_*).

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Select output data type in POL/L1B products with a number
specified at TYPEPOL.
-b TYPEPOL

The definitions of numbers are as follows:-1 = output only stokes parameters (Lt_PI*, Lt_PQ*, Lt_PU*)
1 = output only polarimetric raw images (Lt_P1*, Lt_P2*)
0 = output all the images
Set the upper latitude at UPPERLAT for the projection of-u UPPERLAT

POL/L1B products. This is mandatory for POL/L1B products.
The unit is 0.1 degree.
Set the lower latitude at LOWERLAT for the projection of
POL/L1B products. This is mandatory for POL/L1B products.

-l LOWERLATThe unit is 0.1 degree.
The maximum/minimum ranges between upper- and lowerlatitudes are 15.0 degrees/5.0 degrees respectively.
Select a tilt angle to be projected for imageries including tiltdriving in POL/L1B products with a number specified at TILT.
The definitions of numbers are as follows:-t TILT0 = the tilt angle before the driving is used.
1 = the tilt angle after the driving is used.
If this is not specified (default), the projection of two tilt angles
are delimited at the line of the driving-center on the ground.
Set band offset/scaling(slope) values from HDF attributes to
GDAL_METADATA Tag (42112) with an option specified at
METADATA. This is equivalent to options of -a_scale/-a_offset-a METADATA

in gdal_transrate. The definition of the options is as follows:default = default Offset/Slope in HDF attributes are set,reflectance = Offset_reflectance/Slope_reflectance in HDF
attributes are set.
Set nodata value to GDAL_NODATA Tag (42113) with an-n NO_DATA

option specified at NO_DATA. This is equivalent to the optionof -a_nodata in gdal_transrate. (ex: -n 65535). Only one
nodata value can be set in each output file.

-z

Apply the LZW compression to the images.

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Set the target datasets at DATASET for band-composite file
output. This is applicable for images in Image_data group as
follows:
L1B or L2/LTOA = Lt_* and QA_flag,
L2/RSRF = Rs_*,Tb_*,Rp_*, and QA_flag,
Others = QA_flag and its corresponding one uint16 image.
Specify target band-names separated by commas (,) without
any blanks. The applicable band-names for L1B, L2/LTOA, or
L2/RSRF are as follows:
VN01,VN02,VN03,VN04,VN05,VN06,VN07,
VN08,VN09,VN10,VN11,VN08P,VN11P,
SW01,SW02,SW03,SW04,TI01,TI02,
P1_p60,P1_0,P1_m60,P2_p60,P2_0,P2_m60,
PI01,PQ01,PU01,PI02,PQ02,PU02,PL01,PL02,
QA_flag,-c DATASET(ex: -c VN03,VN05,VN08,QA_flag).
The hyphen(-) can be used to specify successive bandnumbers for the band-names in ascending order(ex: -c VN01-11,SW01-03).
The wildcard(*,?) can be used except for a first character ofthe band-name (i.e., V, S, T, or P) in double quotes(ex: -c "SW*,TI*", -c "P?01").
When images that have different original pixel spacing are
specified, the pixel spacing of the output images are set basedon the minimum of them, while the output images which haveother pixel spacing are oversampled to it.
For L2-scenes or -tiles except for LTOA and RSRF, specify thetarget data-name and its corresponding QA_flag separated by
a comma (,) without any blanks.
(ex: -c SST,QA_flag)
If options of -c and -d are specified at the same time, the option-c is valid while the option -d is ignored.

-hPrint a usage message and exit.

-v

Print version and license information and exit.

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Examples:
1) Process all images (Lt_*), mask stray-light flags, the resampling is NN, thespacing is 10 arc-sec, the output directory is “./output” for L1B/VNR product.
> SGLI_geo_map_linux.exe [L1B/VNR].h5 -m -r 0 -s 10.0 -o ./output
2) Process Image_data/Lt_VN11, mask stray-light flags, the output directory is “./”(current) for L1B/VNR product.
> SGLI_geo_map_linux.exe [L1B/VNR].h5 -d Image_data/Lt_VN11 -m
3) Process Geometry_data/Sensor_zenith, the output directory is “./” (current) for
L1B/VNR product.
> SGLI_geo_map_linux.exe [L1B/VNR].h5 -d Geometry_data/Sensor_zenith
4) Process Image_data/Lt_TI01, the map projection is PS, the output directory is “./”(current) for L1B/IRS product.
> SGLI_geo_map_linux.exe [L1B/IRS].h5 -d Image_data/Lt_TI01 -p
5) Process all images (Lt_*), the latitude-range is N45 to N30, for L1B/POL product.
> SGLI_geo_map_linux.exe [L1B/POL].h5 -u 45.0 -l 30.0
6) Process Image_data/Lt_VN11, mask stray-light flags, the output directory is “./”(current) for L2/LTOA product.
> SGLI_geo_map_linux.exe [L2/LTOA].h5 -d Image_data/Lt_VN11 -m

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5． Output FilesThe output files are map-projected imageries in GeoTIFF (.tif) format and ancillary
information in XML (.xml) format for processed datasets in an input HDF product file.
The file is separated into two files at the longitude 180 degrees when the imagery
projected on the geodetic latitude and longitude coordinates overlaps the longitude 180
degrees.

5.1

File naming

The rules of naming for output files are as follows:
L1B POL without option –t:
GID_ULAT_LLAT_SDS.tif/.xml
where,GID is the Granule ID of an input HDF product,
ULAT is the upper latitude specified at the option –u (S90.0~N90.0),
LLAT is the lower latitude specified at the option -l (S90.0~N90.0),
SDS is the name of a dataset.
Example:GC1SG1_201806250054L04800_1BSG_POLDK_1002_N45.0_N30.0_Lt_P1_0.tif
GC1SG1_201806250054L04800_1BSG_POLDK_1002_N45.0_N30.0_Lt_P1_0.xml
L1B POL with option –t:
GID_ULAT_LLAT_TILT_SDS.tif/.xml
where,
TILT is the tilt-angle of pre- or post-driving (T-45~T+45)
Example:GC1SG1_~(same as above example)~_N45.0_N30.0_T+45_Lt_P1_0.tif
GC1SG1_~(same as above example)~_N45.0_N30.0_T+45_Lt_P1_0.xml
Other:
GID_SDS.tif/.xml
Example:GC1SG1_201806250119R04810_1BSG_VNRDQ_1002_Lt_VN11.tif
GC1SG1_201806250119R04810_1BSG_VNRDQ_1002_Lt_VN11.xml

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Separated files overlapping longitude 180 degrees:“_E” and “_W” are added at the ends of file names (without extensions) for separated
files, where the former and the latter are the imageries in the eastern side (~180°)
and in the western side (-180°~) respectively.
Example:GC1SG1_202107030044H04008_1BSG_IRSDQ_2003_Lt_TI01_E.tif
GC1SG1_202107030044H04008_1BSG_IRSDQ_2003_Lt_TI01_E.xml
GC1SG1_202107030044H04008_1BSG_IRSDQ_2003_Lt_TI01_W.tif
GC1SG1_202107030044H04008_1BSG_IRSDQ_2003_Lt_TI01_W.xml
SDS name for output files processed with the band-composite option -c:
The specified characters at DATASET are used as it is for the SDS name after thecommas and the wildcard characters (*,?) are replaced to ‘_’ and ‘x’, respectively.
The datatype-identifiers (Lt_, Rs_, Tb_, or Rp_) are inserted ahead each of the bandnames for L1B or L2/LTOA or L2/RSRF. If the QA_flag is specified, it is attached at
the end of the SDS name..
Example:Option: -c VN03,VN05,VN08
GC1SG1_202103100138K05510_1BSG_VNRDQ_2002_Lt_VN03_VN05_VN08.tif
GC1SG1_202103100138K05510_1BSG_VNRDQ_2002_Lt_VN03_VN05_VN08.xml

Option: -c "SW*,TI*,QA_flag"
GC1SG1_202103100138K05510_1BSG_IRSDQ_2002_Lt_SWx_Tix_QA_flag.tif
GC1SG1_202103100138K05510_1BSG_IRSDQ_2002_Lt_SWx_Tix_QA_flag.xml

Option: -c "V*,S*,T*,P*"GC1SG1_20210310D01D_T0529_L2SG_RSRFQ_2000_Rs_Vx_Sx_Tb_Tx_Rs_Px.tif
GC1SG1_20210310D01D_T0529_L2SG_RSRFQ_2000_Rs_Vx_Sx_Tb_Tx_Rs_Px.xml

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5.2

GeoTIFF tags/keys

Table 5.2-1 and 5.2-2 show the tags and keys respectively in the output GeoTIFF files.
Table 5.2-1 TIFF tag settings
Tag

Value

TIFFTAG_IMAGEWIDTH

image width

TIFFTAG_IMAGELENGTH

image height

TIFFTAG_BITSPERSAMPLE

8 or 16COMPRESSION_NONE or

TIFFTAG_COMPRESSIONCOMPRESSION_LZWTIFFTAG_PHOTOMETRIC

PHOTOMETRIC_MINISBLACKTIFFTAG_ORIENTATIONORIENTATION_TOPLEFT

TIFFTAG_SAMPLESPERPIXEL

1 to n (if option -c specified)

TIFFTAG_ROWSPERSTRIP

image height
SAMPLEFORMAT_INT or

TIFFTAG_SAMPLEFORMATSAMPLEFORMAT_UINTTIFFTAG_PLANARCONFIG

1 or 2 (if option -c specified)

TIFFTAG_GDAL_METADATA*

xml data

TIFFTAG_GDAL_NODATA*

text data

GTIFF_TIEPOINTS

6 parameters of model tie point tag

GTIFF_PIXELSCALE

3 parameters of model pixel scale tag

GTIFF_ASCIIPARAMS

text data*) Extended tags

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Table 5.2-2 GeoTIFF key settings
Key

Value

GTModelTypeGeoKey

ModelTypeProjected

GTRasterTypeGeoKey

RasterPixelIsArea

GeographicTypeGeoKey

GCS_WGS_84

GeogAngularUnitsGeoKey

Angular_Degree

GTCitationGeoKey

text data

PCSCitationGeoKey

text data

GeogLinearUnitsGeoKey (PS only)

Linear_Meter

ProjectedCSTypeGeoKey (PS only)

KvUserDefined

ProjectionGeoKey (PS only)

KvUserDefined

ProjCoordTransGeoKey (PS only)

CT_PolarStereographic

ProjLinearUnitsGeoKey (PS only)

Linear_Meter
latitude of the image projection plane

ProjNatOriginLatGeoKey (PS only)(= 71 or -71)

ProjStraightVertPoleLongGeoKey (PSlongitude as the vertical axis of the

only)image frame (= 0)ProjFalseEastingGeoKey (PS only)

0

ProjFalseNorthingGeoKey (PS only)0

The reference information of the GeoTIFF format is as follows:
GeoTIFF Format Specification
GeoTIFF Revision 1.0
Specification Version: 1.8.2
Last Modified: 28 December, 2000.
http://geotiff.maptools.org/spec/geotiffhome.html (accessed Jul. 1, 2021)

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5.3

XML ancillary file

Table 5.3-1 shows the settings of tags and contents in the output XML files.
Table 5.3-1 Tags and contents in the output XML files
Tags

Contents

GeoTIFFAncillary
Process_information
Software_name

The name of the tool.

Software_version

The version of the tool.

Processing_time

Local (CPU) day/time of the processing.

Map_projection
Pixel_spacing

Selected map projection (“Geodetic
Latitude/Longitude” or “Polar Stereographic”).
Pixel spacing (in degrees for Lat/Lon or in meters
for PS).

Resampling_method

Resampling method (“NN”, “BL”, or “CC”).

MSB2bitsMask“Applied” or “None”.

Upper_latitude
Lower_latitude
Fixed_tilt_angle

Upper latitude specified at option –u (onlyL1B/POL).
Lower latitude specified at option –l (onlyL1B/POL).
“Pre-angle of tlit-driving” or “Post-angle of tiltdriving” (only L1B/POL with option –t).

Data_information
Granule_ID

Granule ID of processed HDF product.

Dataset_name /Name of the processed HDF dataset.

Dataset_nn_name

Band no. (nn) is inserted for band-composite files.

HDF_attributes
Global_attributes
Scene_start_time/

Scene or Image start time is set as the names of

Image_start_time

XML tags are copied from the HDF attributes

Scene_end_time/

Scene or Image end time is set as the names of

Image_end_time

XML tags are copied from the HDF attributes

Image_data or Geometry_data (Parent group of the processed dataset)
attributes

All attributes in the HDF Group are set as the(the names of HDF

names of XML tags are copied from the names ofGroup attributes)

HDF attributes.

SDS_name (the name of the processed dataset)
attributes

All attributes in the HDF dataset are set as the(the names of HDF

names of XML tags are copied from the names ofdataset attributes)

HDF attributes.

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6． License information
The tool includes the open-source libraries for the file interface of the HDF5 and the
GeoTIFF. Their license information is as follows:
Copyright Notice for HDF5 (Hierarchical Data Format 5) Software Library========================================================
HDF5 (Hierarchical Data Format 5) Software Library and Utilities
Copyright (c) 2006-2018, The HDF Group.
NCSA HDF5 (Hierarchical Data Format 5) Software Library and Utilities
Copyright (c) 1998-2006, The Board of Trustees of the University of Illinois.
All rights reserved.
https://www.hdfgroup.org/licenses (accessed Jul. 1, 2021)

libgeotiff Licensing==============
Code by Frank Warmerdam has this copyright notice:* Copyright (c) 1999, Frank Warmerdam
Code by Niles Ritter is under this licence:*

Written By: Niles D. Ritter.

* Copyright (c) 1995, Niles D. Ritter
https://github.com/OSGeo/libgeotiff/blob/master/libgeotiff/LICENSE(accessed Jul. 1, 2021)

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7． Appendix
7.1

The map projection for imageries in SGLI/HDF productsThis section briefly explains the algorithms of map projections for the SGLI datasets inthis tool.
L1B scene/half-path products
For the L1B scene/half-path products, the Rational Polynomial Coefficients (RPC) isinternally generated and used for the map projection. The RPC is a rational polynomial
function of three-degrees, which transform the three-dimensional coordinates ofobject-space (X, Y, Z) into the two-dimensional coordinates of image-space (L, P), andis also being used in the ortho-projection in the latest version of L2/LTOA. The equationof the RPC is as follows:

𝑓𝑓 �𝑋𝑋 ′ ,𝑌𝑌 ′ ,𝑍𝑍 ′ �

𝑓𝑓 �𝑋𝑋 ′ ,𝑌𝑌 ′ ,𝑍𝑍 ′ �

𝐿𝐿′ = 𝑓𝑓1 (𝑋𝑋 ′ ,𝑌𝑌 ′ ,𝑍𝑍 ′ ), 𝑃𝑃′ = 𝑓𝑓3 (𝑋𝑋 ′ ,𝑌𝑌 ′ ,𝑍𝑍 ′)2

4𝑓𝑓(𝑋𝑋, 𝑌𝑌, 𝑍𝑍) = 𝑐𝑐1 + 𝑐𝑐2 𝑌𝑌 + 𝑐𝑐3 𝑋𝑋 + 𝑐𝑐4 𝑍𝑍 + 𝑐𝑐5 𝑋𝑋𝑋𝑋 + 𝑐𝑐6 𝑌𝑌𝑌𝑌+𝑐𝑐7 𝑍𝑍𝑍𝑍 + 𝑐𝑐8 𝑌𝑌 2 + 𝑐𝑐9 𝑋𝑋 2 +𝑐𝑐10 𝑍𝑍 2

+ 𝑐𝑐11 𝑋𝑋𝑋𝑋𝑋𝑋 + 𝑐𝑐12 𝑌𝑌 3 + 𝑐𝑐13 𝑋𝑋 2 𝑌𝑌 + 𝑐𝑐14 𝑍𝑍 2 𝑌𝑌 + 𝑐𝑐15 𝑌𝑌 2 𝑋𝑋 + 𝑐𝑐16 𝑋𝑋 3 +𝑐𝑐17 𝑍𝑍 2 𝑋𝑋
+ 𝑐𝑐18 𝑌𝑌 2 𝑍𝑍 + 𝑐𝑐19 𝑋𝑋 2 𝑍𝑍 + 𝑐𝑐20 𝑍𝑍 3𝐿𝐿′ =𝐿𝐿−𝐿𝐿𝑜𝑜
𝐿𝐿𝑠𝑠, 𝑃𝑃′ =𝑃𝑃−𝑃𝑃𝑜𝑜𝑃𝑃𝑠𝑠, 𝑋𝑋′ =𝑋𝑋−𝑋𝑋𝑜𝑜𝑋𝑋𝑠𝑠, 𝑌𝑌′ =𝑌𝑌−𝑌𝑌𝑜𝑜𝑌𝑌𝑠𝑠, 𝑍𝑍′ =𝑍𝑍−𝑍𝑍𝑜𝑜
𝑍𝑍.

The generation of the RPC is based on the rigorous projection model which consistsof the physical sensor model of the SGLI, the orbit/attitude data of the GCOM-C, andthe alignment models of the instruments, which are included in the L1B HDF products.
Figure 7.1-1 shows the schematic view of the projection model for the RPC generation.
To cover the relatively wide areas (swath and lines) of the SGLI scene/half-path,multiple RPCs are generated internally for divided blocks of the imagery.

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P
image space
(L1B)

L

focal point(satellite) orbitZ
objectspace

6000m
elevation
layer
0m

Y

X
Geodetic / Map Coordinates

Fig. 7.1-1

Projection model for the RPC generation.

In the map projection, the output frame on the selected map coordinates is defined firstby using the corner latitudes and longitudes of the scene. For POL imageries of halfpaths, the range of latitudes specified with the tool-options is used instead. Then gridsof fixed intervals are defined on the frame of output imagery and their corresponding
addresses on the input L1B imagery are calculated with the RPCs. The map addressof the grid on the output imagery is converted into the one defined for the RPC input.
The height (Z) input to the RPC is fixed to 0 (zero) since there is no input of the Digital
Elevation Model (DEM), so that the imagery is projected onto the reference ellipsoid(GRS80). Therefore, the ortho(terrain)-correction is not applied in the output imageries,
whereas it is being applied in all the L2-tile products that are derived from the LTOA.
Finally, all the corresponding addresses between the whole output imagery and the
input L1B imagery are calculated with the bi-linear interpolation on the ones at the gridsof fixed intervals. The digital values of pixels in whole output imagery are resampledfrom the input L1B imagery with them.

L2 scene products
For the L2 scene products, the RPC is not available since the HDF files do not include
the data to reconstruct the rigorous projection model. Instead, the latitude andlongitude data on the grids of 10 pixel intervals on the imagery, which are included at
the group of Geometry_data in the HDF file, are used for the projection. The addresson the input imagery corresponding to any latitude and longitude inside the scene iscalculated with the bi-linear interpolation from the samples of its surrounding four grids

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User’s Manual

Version 1.2, Oct. 2023

on the latitude and longitude data.
The procedure of the projection is the same as the one for the L1B scene/half-path
products except for the calculation of corresponding addresses between the output andinput imageries at the grids defined on the output imagery. However, the processing
time is larger than that of the process with RPCs because it includes a searching stepin the latitude and longitude data while there is no such step in the process with RPCs.
The ortho(terrain)-correction is not applied in the output imageries as well.

L2 tile products
For the L2 tile products, the projection is directly performed with the equation between
the sinusoidal coordinates of the input tile and the geodetic latitude and longitude
coordinates defined as follows:x=m(λ cos ϕ '−10h + 180)
+ 0.5 ,10y=n(90 − 10v − ϕ )+ 0.5 ,
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ϕ ′ = ϕ ⋅ π / 180m=n=4800 (250m mode)
1200 (1km mode).

where, (x, y) is the address on the imagery, (ϕ, λ) is the geodetic latitude and longitude,and (v, h) is the vertical and horizontal tile number. The origin of the address on theimagery is the upper-left corner of the tile, where the center of the pixel is defined as(1, 1).
For the projection on the Polar-stereo coordinates, the conversion to the latitude andlongitude coordinates is additionally used. The frame of the output imagery isdetermined from the range of valid pixels on the dataset.

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