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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?