Database for API

Overview

The database for API contains COG(Cloud Optimized GeoTIFF) and STAC(Spatio Temporal Asset Catalog). COG is one of the TIFF formats that can be obtained through http range request depending on the user’s area of interest, and resolution. STAC is catalog information in hierarchical JSON format to access COG. The database’s specification which consists of COG and STAC is determined to accomplish effective data distribution by API for various earth observation satellite images which can be projected on the map.

Note

Attention! Land Cover Class data is for in 2019 only, GCOM-C SGLI data (RGB) is for in Dec, 2021 only, Forest Non Forest data is from 2017 to 2020, JASMES japan area’s data is from 2020 to 2022/9.

Datasets

All COG/STAC datasets in the database is visualized and cataloged in the site below. In this site, users can view and check the visualized data without any preparation.

https://data.earth.jaxa.jp/en/datasets/

Structure

COG/STAC structure is designed to effectively deliver the Earth observation data depending on the user query.

COG (Cloud Optimized GeoTIFF)

If you would like to know general information of COG, please check the official site below.

https://www.cogeo.org/

In the database, we have defined COG levels so that the database can store many kinds of resolution and area levels. Table 1 and 2 shows the definition of COG levels in the database. Each COG has up to two internal IMG levels. Figure 1 shows the relation between COG level and IMG level.

Figure 1 Relation between COG level and IMG level

The IMG level that each COG will have will depend on the selected maximum PPU (Pixels Per Unit(1 degree (EPSG4326) or 32786m(EPSG3995/EPSG3031))). The collection’s maximum PPU will be selected from the table above the original PPU. All images below the maximum resolution are generated. For example, if the original data’s PPU is 7, the database’s maximum PPU is 10, and 5,2.5,1.25 PPU image is created as COG. Thus, COG level 0 (internal IMG level number is three) and COG level 1 (internal IMG level number is one) will be generated.

Table 1 : COG levels in the database (EPSG4326)

COG level	Image Size (degree)	IMG level	Image Size (pixels)	PPU
level 0	180/180 deg	level 2	225/225 pixels	1.25
		level 1	450/450 pixels	2.5
		level 0	900/900 pixels	5
level 1	90/90 deg	level 2	900/900 pixels	10
		level 1	1800/1800 pixels	20
		level 0	3600/3600 pixels	40
level 2	10/10 deg	level 2	900/900 pixels	90
		level 1	1800/1800 pixels	180
		level 0	3600/3600 pixels	360
level 3	1/1 deg	level 2	900/900 pixels	900
		level 1	1800/1800 pixels	1800
		level 0	3600/3600 pixels	3600
level 4	0.1/0.1 deg	level 2	900/900 pixels	9000
		level 1	1800/1800 pixels	18000
		level 0	3600/3600 pixels	36000

Table 2 : COG levels in the database (EPSG3995/EPSG3031)

COG level	Image Size (m)	IMG level	Image Size (pixels)	PPU
level 0	2^24/2^24 m	level 2	512/512 pixels	1
		level 1	1024/1024 pixels	2
		level 0	2048/2048 pixels	4
level 1	2^21/2^21 m	level 2	512/512 pixels	8
		level 1	1024/1024 pixels	16
		level 0	2048/2048 pixels	32
level 2	2^18/2^18 m	level 2	512/512 pixels	64
		level 1	1024/1024 pixels	128
		level 0	2048/2048 pixels	256

STAC (Spatio Temporal Asset Catalog)

If you would like to know general information of STAC, please check the official site below.

https://stacspec.org/

STAC of the database mainly has five kinds of layers such as collection, date, cog level, longitude, and latitude. Only date layers may have multiple STAC layers depending on the temporal resolution. Table 3 shows the definition of the STAC levels of the database.

Table 3 : STAC layers

layer name	number of layers	stac type	description
collection	1	collection	Collection’s name. Organization name, Satellite, Sensor, Original Product’s name, version, area are concatenated as the name.
date	from 1 to 3	catalog	The value represents observation date.
cog level	1	catalog	The value represents COG level.
longitude	1	catalog	COG’s minimum longitude and maximum longitude are used as the name.
latitude	1	item	COG’s minimum latitude and maximum latitude are used as the name.