LSA SAF products: files and formats

Carla Barroso, IPMA

Application of Remote Sensing Data for Drought Monitoring

Introduction to Eumetsat LANDSAF Products

11-15 November Slovenia

� Where to get the data

� Product File Structure

� Quick visualization of products

� GIS tools for visualization & analysis

� LSA SAF Products Coordinate System

� LSASAF Georeferencer Tool

OUTLINE

How do you obtain LSA SAF

products?

LSA SAF

website, helpdesk

EUMETCast

How do you obtain LSA SAF

products?

LSA SAF

website, helpdesk

EUMETCast

See Product User Manuals

And also

• Algorithm Theoretical Basis Document

• Validation Report

• Product Output Format

Peer Reviewed Publications

Product Documentation

� Product User Manual (PUM)

� Main documentation source

− Physical phenomena

− Algorithm basis

− Output data specifications

− Etc.

� Product Output Format (POF)

� Details concerning description of metadata, file naming formats, etc.

� Validation Report (VR)

� Algorithm Theoretical Basis Document (ATBD)

Product file structure

� LSA SAF products use the HDF5 format

� http://www.hdfgroup.org/

� Hierarchical Data Format (HDF)

� Groups – Containers for datasets and other groups

� Datasets – Multidimensional arrays of a homogeneous type

� Attributes – Metadata on groups and datasets

� HDF files:

� Are self-describing.

� Support n-dimensional datasets

� LSA SAF HDF5 files:

� A common set of attributes on the root group

− general information

� A dataset for the main product (LST, DSLF, etc)

� Additional datasets for metadata (Quality flags, Error flags, etc.)

� Each dataset may have:

− Specific attributes (Scaling factor, missing value, etc.)

− Different dimensions (Most datasets are 2D)

− Different data types (Most datasets are 16bit signed integers)

Product file structure

Quick visualization of products

� HDFView software

http://www.hdfgroup.org/hdf-java-html/hdfview/index.html#download_hdfview

� Java-based HDF Viewer

� Inspection of a HDF5's structure and data

� Visualize data in spreadsheet or image mode

� Basic statistics, line plotting and histogram generation

� Export to image formats

Have you used HDFViewbefore?Yes

HDFView

1. Datasets

2. Attributes

3. Table View

4. Table options

5. Image view

6. Image options

7. Pixel values

HDFView

Inspecting file and dataset attributes

HDFView

� When visualizing products take

note:

1. Cell values are unscaled

2. The 'missing value' values

have no physical meaning

3. Product is not georeferenced

(line, column coordinates only)

GIS tools for visualization & analysis

� ILWIS

� Direct import of LSASAF products through the GEONETCast toolbox

� Other tools (ArcGIS, Mapinfo, SAGA, etc.)

ILWIS

� Integrated Land and Water Information System

� http://52north.org/communities/ilwis/

� Open Source GIS software

� Available only for MS Windows (as of now)

� Imports LSA SAF products, using the GEONETCast Toolbox

� Several modules for raster and vector processing

GEONETCast Toolbox

� GEONETCast Toolbox

� http://52north.org/communities/earth-observation/geonetcast-toolbox-software

� Available as a toolbox for ILWIS

� Developed by ITC – University of Twente

� Enables easy access to and management of GEONETCast data

− various satellite and environmental data and/or resulting products

� Tailored for users running GEONETCast reception stations

ILWIS/GEONETCast

� Installation

� Follow the GEONETCast Toolbox's user manual

� Read section 1.1 and 1.2 CAREFULLY

� Importing LSA SAF products

� Beware of file names:

− Files obtained through GEONETCast (EUMETCast)

� S-LSA_-HDF5_LSASAF_MSG_LST_Euro_201111060000.bz2

� Everything will work OK

− Files obtained through LSA SAF's on-demand dissemination

� HDF5_LSASAF_MSG_LST_Euro_201111060000.bz2

� GEONETCast Toolbox expects the 'S-LSA_-' prefix and will throw

errors

� Solutions:

− Uncompress → rename → recompress (time consuming and

boring)

− Modify the GEONETCast's batch import scripts

− Contact LSA SAF's helpdesk and they'll send you the modified scripts

ILWIS/GEONETCast

Modular user interface, integrating the GEONETCast Toolbox

ILWIS/GEONETCast

ILWIS/GEONETCast

Use native NGP projection of the LSA SAF products

� Normalized Geostationary

Projection (NGP)

� Projection of the underlying MSG LRIT source data

� Important parameters for MSG

satellite:

− Satellite height above ellipsoid: 35785831 m

− Central meridian: 0º

� Documented on EUMETSAT's

LRIT and HRIT Global

Specification

− http://www.eumetsat.int/groups/cps/documents/document/pdf_c

gms_03.pdf

LSA SAF Product Coordinate System

LSA SAF Product Coordinate System

� LSA SAF products hold coordinate system information in the attributes of the

root group

� But HDF5 files have no standard way of defining coordinate systems

� It's hard to automatically import LSA SAF products into a Geographical

Information System (GIS) software AND have the data correctly georeferenced

Visualization of LSA SAF products

HDFView is nicefor a quick inspection

Some GIS toolscan open HDF5 directly

BUT ...

GIS tools are nice forvisualization, analysis

map making, etc.

Most GIS tools cannotrecognize LSA SAF

coordinate information

The files will not beprojected

It won't be possible tooverlay different data

UNLESS …

� A graphical tool for georeferencing LSA SAF products

� Still in-development, but already usable

� Open development

� Source code hosted on a public repository

� https://github.com/ricardogsilva/LSASAF-georeferencer

� Uses open source tools

� Python, GDAL, Proj, Qt4

� Multi-platform

LSASAF Georeferencer Tool

� Convert LSASAF HDF5 files to GeoTiff

� GeoTiff is a Tiff based interchange format for georeferenced raster

imagery

� Reproject from the NGP projection to other coordinate systems

� Apply scaling factor and missing value information to the output file

� Output GeoTiff files are suitable for further processing in GIS software

� Process multiple files simultaneously

LSASAF Georeferencer Tool

� Graphical Window usage example

1. Select the file(s) to process

2. Load file information

3. Choose the dataset(s) to be

processed

4. Choose the output projection

5. Choose the output directory

6. Process the files

LSASAF Georeferencer Tool

LSASAF Georeferencer Tool

� Command line usage example

# display usage information

ricardo@geo2:~$ ./georef_hdf5.py -h

# process all the LST files in ~/input_dir

ricardo@geo2:~$ ./georef_hdf5.py -x -o ~/my_output_dir ~/input_dir/*LST*

4 production areas for MSG

- Europe

- Northern Africa

- Southern Africa

- Southern America

Geostationary Projection

3 km at sub-satellite point

LSA SAF Products

1701 cols x 651 lines

2211 cols x 1151 lines

1211 cols x 1191 lines

701 cols x 1511 lines

Merging MSG areas

Geostationary Projection

3 km at sub-satellite point

3712 columns x

3712 lines

1550

1240

40

2140

1460

700

1850

50

Form 1 matrix for the whole disk

[3712 x 3712]

taking into account that for LSA SAF areas top line in the disk

is

and left column is

XX

XX

LSA SAF Products

Questions/Comments?

carla.barroso@ipma.pt