O2A GeoTIFF (`.sdi.tif`)

Author	Andreas Walter
Technical Contacts	Andreas Walter, Peter Konopatzky
Version	1.2.1

This document formerly lived on AWI Confluence and has been migrated here with only minor changes. It has been backdated.

Basics

The O2A GeoTIFF is a specification of the metadata tags nomenclature inside a GeoTIFF used in the O2A dataflow. It extends the public GeoTIFF format with defined metadata tags which are used in the O2A dataflow.

GeoTIFF with WKT representation of the coordinate reference system (it needs to be a CRS existing in the EPSG library and additional metadata tags holding dataset-specific information.

An O2A GeoTIFF needs to contain all the following metadata tags. If a value is not known, the key can be omitted or the value can be filled in with the word "void".

Some values are mandatory, some are mandatory in specific cases* and some are not mandatory.

Metadata Tag	Value mandatory?	Description	Example Values
Coordinate System	yes	The Coordinate System (SRS, CRS) must be written in the WKT format and must be valid against the EPSG code representation. If not, it won't be accepted.	WKT of EPSG:4326: https://epsg.io/4326.wkt
`DATE_TIME` or `DATE_TIME_START` `DATE_TIME_END`	no	Date/Time of the data, in the ISO 8601 format. Either one timestamp (`DATE_TIME`) or two timestamps for time series (`DATE_TIME_START`, `DATE_TIME_END`). Note: Folder Naming Specifications and File Naming!	`YYYY-MM-DDThh:mm:ss` (pattern, not an example!) `2000-01-01T00:00:00`

`PARAMETER_NAME`	no	Name of measured or calculated parameter.	`sea ice concentration` `elevation`
`PARAMETER_URN`	no	A parameter urn of the dataset as defined in registry.awi.de or built from a PANGAEA DOI.	`satellite:gcomw1:amsr2:l2:sic` `pangaea:893351:M132_bathy_data-products:M132_soundings_WGS84:multibeam`
`PARAMETER_UNIT`	no	The unit (or unit symbol) of the given parameter.	`%`, `m`, `meter`

`METHOD`	no	Name of method used for measurement (observation, ...) data.
`DEVICE`	no	Name or ID of device used for measurement (observation, ...) data.
`SOURCE`	yes	URL of data source.	https://doi.pangaea.de/10.1594/PANGAEA.893351?format=textfile
`DOI`	yes*	URL to DOI.	https://doi.pangaea.de/10.1594/PANGAEA.893351
`REGISTRY_URI` (formerly `SENSOR_URI`)	yes*	URL of a registry.awi.de handle (handle!!).	https://hdl.handle.net/10013/sensor.3a51c0c1-4822-476d-be31-9f80a9ef36e4
`LICENSE`	yes	License of the dataset.	`MIT`, `CC BY-NC 3.0`

`PLATFORM`	no	Name of platform.	`Polarstern`
`EXPEDITION_NAME`	yes*	Name of expedition (campaign, cruise, ...) where data was gathered.	`PS001/1`
`EXPEDITION_ALIAS`	no	Alias of expedition (campaign, cruise, ...) where data was gathered.	`ARK-I/1`

`EVENT_NAME`	yes*	Name of expedition event where data was gathered. Mostly as dataset its registered in PANGAEA.	`PS001/1-0001`
`EVENT_ALIAS`	no	Alias of expedition event where data was gathered. Mostly as dataset its registered in PANGAEA.	`ARK-I/1-1`

* mandatory only if the data set is registered in PANGAEA.

Examples

Metadata like in the following examples could be retrieved by using the gdalinfo command like this:

bash

gdalinfo ./path/to/file.sdi.tif

REGISTRY item

bash

Driver: GTiff/GeoTIFF
Files: ../platforms/satellite/gcomw1/amsr2/l2/sic/data/2019/05/21/asi-AMSR2-n3125-20190521_EPSG4326.tif
Size is 4268, 4268
Coordinate System is:
  PROJCS["WGS 84 / Arctic Polar Stereographic",
    GEOGCS["WGS 84",
      DATUM["WGS_1984",
        SPHEROID["WGS 84",6378137,298.257223563,
          AUTHORITY["EPSG","7030"]],
        AUTHORITY["EPSG","6326"]],
      PRIMEM["Greenwich",0,
        AUTHORITY["EPSG","8901"]],
      UNIT["degree",0.0174532925199433,
        AUTHORITY["EPSG","9122"]],
      AUTHORITY["EPSG","4326"]],
  PROJECTION["Polar_Stereographic"],
  PARAMETER["latitude_of_origin",71],
  PARAMETER["central_meridian",0],
  PARAMETER["scale_factor",1],
  PARAMETER["false_easting",0],
  PARAMETER["false_northing",0],
  UNIT["metre",1,
    AUTHORITY["EPSG","9001"]],
  AXIS["X",EAST],
  AXIS["Y",NORTH],
  AUTHORITY["EPSG","3995"]]
Origin = (-6527893.000000000000000,6882500.000000000000000)
Pixel Size = (3125.000000000000000,-3125.000000000000000)
Metadata:
  AREA_OR_POINT=Area
  grid_information=longitude-latitude grid for these data to be found at: https://seaice.uni-bremen.de/data/grid_coordinates/n3125/
  long_name=ASI Ice Concentration, Version: 5.4, 20190521, res: 3.12500, AMSR2, Region: Arctic3125
  valid_range=0, 100
  DATE_TIME=2019-05-21T00:00:00
  DEVICE=Advanced Microwave Scanning Radiometer 2 (AMSR2)
  METHOD=Advance Microwave
  SOURCE=https://seaice.uni-bremen.de/data/grid_coordinates/n3125/
  LICENSE=unknown
  PARAMETER_NAME=sea_ice_concentration
  PARAMETER_UNIT=%
  PARAMETER_URN=satellite:gcomw1:amsr2:l2:sic 
  Image Structure Metadata:
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left (-6527893.000, 6882500.000) (136d30'52.93"W, 15d 7'10.61"N)
Lower Left (-6527893.000,-6455000.000) ( 45d19'18.07"W, 16d55'59.58"N)
Upper Right ( 6809607.000, 6882500.000) (135d18'18.09"E, 13d58'41.21"N)
Lower Right ( 6809607.000,-6455000.000) ( 46d31'52.83"E, 15d43'36.08"N)
Center ( 140857.000, 213750.000) (146d36'57.28"E, 87d38'39.46"N)
Band 1 Block=512x512 Type=Float32, ColorInterp=Gray
  Min=0.000 Max=100.000
  Minimum=0.000, Maximum=100.000, Mean=89.065, StdDev=23.340
  NoData Value=0
  Overviews: 2134x2134, 1067x1067, 534x534, 267x267, 134x134, 67x67
Metadata:
    STATISTICS_MAXIMUM=100
    STATISTICS_MEAN=89.065134675115
    STATISTICS_MINIMUM=0.0002532234066166
    STATISTICS_STDDEV=23.340079762818

PANGAEA

bash

Driver: GTiff/GeoTIFF
Files: ../pangaea/893351/M132_bathy_data-products/M132_soundings_WGS84/M132_soundings_EPSG4326_2016-11-15.tif
Size is 4268, 4268
Coordinate System is:
  PROJCS["WGS 84 / Arctic Polar Stereographic",
    GEOGCS["WGS 84",
      DATUM["WGS_1984",
        SPHEROID["WGS 84",6378137,298.257223563,
          AUTHORITY["EPSG","7030"]],
        AUTHORITY["EPSG","6326"]],
      PRIMEM["Greenwich",0,
        AUTHORITY["EPSG","8901"]],
      UNIT["degree",0.0174532925199433,
        AUTHORITY["EPSG","9122"]],
      AUTHORITY["EPSG","4326"]],
  PROJECTION["Polar_Stereographic"],
  PARAMETER["latitude_of_origin",71],
  PARAMETER["central_meridian",0],
  PARAMETER["scale_factor",1],
  PARAMETER["false_easting",0],
  PARAMETER["false_northing",0],
  UNIT["metre",1,
    AUTHORITY["EPSG","9001"]],
  AXIS["X",EAST],
  AXIS["Y",NORTH],
  AUTHORITY["EPSG","3995"]]
Origin = (-6527893.000000000000000,6882500.000000000000000)
Pixel Size = (3125.000000000000000,-3125.000000000000000)
Metadata:
  AREA_OR_POINT=Area
  DATE_TIME=2007-06-01T00:00:00
  EXPEDITION_NAME=M132
  EVENT_NAME=M132-track
  DEVICE=Atlas Hydrographic Hydrosweep DS 2 multibeam echo sounder
  METHOD=multi-beam echosounders
  SOURCE=https://doi.pangaea.de/10.1594/PANGAEA.893351?format=textfile
  DOI=https://doi.org/10.1594/PANGAEA.893351
  LICENSE=Creative Commons Attribution-NonCommercial 3.0 Unported (CC-BY-NC-3.0)
  PARAMETER_NAME=Elevation
  PARAMETER_UNIT=m
  PLATFORM=Meteor
Image Structure Metadata:
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left (-6527893.000, 6882500.000) (136d30'52.93"W, 15d 7'10.61"N)
Lower Left (-6527893.000,-6455000.000) ( 45d19'18.07"W, 16d55'59.58"N)
Upper Right ( 6809607.000, 6882500.000) (135d18'18.09"E, 13d58'41.21"N)
Lower Right ( 6809607.000,-6455000.000) ( 46d31'52.83"E, 15d43'36.08"N)
Center ( 140857.000, 213750.000) (146d36'57.28"E, 87d38'39.46"N)
Band 1 Block=512x512 Type=Float32, ColorInterp=Gray
  Min=0.000 Max=100.000
  Minimum=0.000, Maximum=100.000, Mean=89.065, StdDev=23.340
  NoData Value=0
  Overviews: 2134x2134, 1067x1067, 534x534, 267x267, 134x134, 67x67
Metadata:
    STATISTICS_MAXIMUM=100
    STATISTICS_MEAN=89.065134675115
    STATISTICS_MINIMUM=0.0002532234066166
    STATISTICS_STDDEV=23.340079762818

Dataset Homogeneity

A Dataset

can be of a single image or multiple images.
can show a topographic expansion of a parameter at a specific time period.
can show a topographic expansion of a parameter over a period of time (time series).

A homogeneous data structure is essential for smooth processing and clean rendering of the dataset. A dataset must therefore have the following properties:

File naming must be consistent.
Metadata keys and values must be consistent.
Pixel data type range must be consistent (e.g. int8, float32, ...).
NoData value must be proper set and consistent (in both pixel values and metadata entries).

File Naming

Data files follow the naming pattern <basename>_<timestamp>_EPSG<code>.sdi.tif and the Exchange Folder Specifications.

Naming Patterns explained:

<basename> can be everything not conflicting with EPSG<code> and/or <timestamp>.
<timestamp> is used to read the date on which the data was observed or recorded, or for which the data was modelled.
- Currently only date (and not time) is supported.
- Needs to be identical with date of DATE_TIME/DATE_TIME_START in GeoTIFF metadata.
- One of the following date formats are supported (for all files in one dataset):
  - YYYYMMDD
  - YYYY-MM-DD
  - YYYY_MM_DD
EPSG<code> is mandatory to allow multiple projections in one folder.

Example

bash

./path/to/data
|-- world/
|   |-- your_dataset_1_EPSG4326_20210101.tif
|   `-- your_dataset_2_EPSG4326_20210101.tif
|-- north/ 
|   |-- your_dataset_1_EPSG3995_20210101.tif
|   `-- your_dataset_2_EPSG3995_20210101.tif
`-- south/
    |-- your_dataset_1_EPSG3031_20210101.tif
    `-- your_dataset_2_EPSG3031_20210101.tif

Example Use Cases

Guides

Specs

O2A GeoTIFF (`.sdi.tif`)

Basics

Examples

REGISTRY item

PANGAEA

Dataset Homogeneity

File Naming

Example

O2A GeoTIFF (.sdi.tif) ​

Basics ​

Examples ​

REGISTRY item ​

PANGAEA ​

Dataset Homogeneity ​

File Naming ​

Example ​

O2A GeoTIFF (`.sdi.tif`)

Basics

Examples

REGISTRY item

PANGAEA

Dataset Homogeneity

File Naming

Example