LSA SAF products: files and formats

Transcription

1 LSA SAF products: files and formats Carla Barroso, IPMA Application of Remote Sensing Data for Drought Monitoring Introduction to Eumetsat LANDSAF Products November Slovenia

2 OUTLINE 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

3 How do you obtain LSA SAF products? EUMETCast LSA SAF website, helpdesk

4 How do you obtain LSA SAF products? EUMETCast LSA SAF website, helpdesk

5

6 See Product User Manuals And also Algorithm Theoretical Basis Document Validation Report Product Output Format Peer Reviewed Publications

7 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)

8 Product file structure LSA SAF products use the HDF5 format 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

9 Product file structure 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)

10 Quick visualization of products HDFView software 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

11 Have you used HDFView Yes before?

12 HDFView 1. Datasets 2. Attributes 3. Table View 4. Table options 5. Image view 6. Image options 7. Pixel values

13 HDFView Inspecting file and dataset attributes

14 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)

15 GIS tools for visualization & analysis ILWIS Direct import of LSASAF products through the GEONETCast toolbox Other tools (ArcGIS, Mapinfo, SAGA, etc.)

16 ILWIS Integrated Land and Water Information System 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

17 GEONETCast Toolbox GEONETCast Toolbox 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

18 ILWIS/GEONETCast Installation Follow the GEONETCast Toolbox's user manual Read section 1.1 and 1.2 CAREFULLY

19 ILWIS/GEONETCast Importing LSA SAF products Beware of file names: Files obtained through GEONETCast (EUMETCast) S-LSA_-HDF5_LSASAF_MSG_LST_Euro_ bz2 Everything will work OK Files obtained through LSA SAF's on-demand dissemination HDF5_LSASAF_MSG_LST_Euro_ 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

20 ILWIS/GEONETCast Modular user interface, integrating the GEONETCast Toolbox

21 ILWIS/GEONETCast Use native NGP projection of the LSA SAF products

22 LSA SAF Product Coordinate System Normalized Geostationary Projection (NGP) Projection of the underlying MSG LRIT source data Important parameters for MSG satellite: Satellite height above ellipsoid: m Central meridian: 0º Documented on EUMETSAT's LRIT and HRIT Global Specification gms_03.pdf

23 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

24 Visualization of LSA SAF products HDFView is nice for a quick inspection GIS tools are nice for visualization, analysis map making, etc. Some GIS tools can open HDF5 directly BUT... Most GIS tools cannot recognize LSA SAF coordinate information The files will not be projected It won't be possible to overlay different data UNLESS

25 LSASAF Georeferencer Tool A graphical tool for georeferencing LSA SAF products Still in-development, but already usable Open development Source code hosted on a public repository Uses open source tools Python, GDAL, Proj, Qt4 Multi-platform

26 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

27 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

28 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*

29 LSA SAF Products 4 production areas for MSG -Europe - Northern Africa - Southern Africa - Southern America Geostationary Projection 3 km at sub-satellite point 1701 cols x 651 lines 2211 cols x 1151 lines 701 cols x 1511 lines 1211 cols x 1191 lines

30 Merging MSG areas LSA SAF Products Geostationary Projection 3 km at sub-satellite point Form 1 matrix for the whole disk [3712 x 3712] 1850 taking into account that for LSA SAF areas top line in the disk is XX and left column is XX 3712 columns x 3712 lines 2140

31 Questions/Comments?