Getting started with Sextant : training exercises SUMMARY - Ifremer

Dernière mise à jour : 05 avril 2012
Getting started with Sextant : training exercises
Objective : This document is a training support. It is intended for users and future users of the
GeoCatalogue Sextant CHARM wishing to learn to use the tool.
Required :
• To Have completed formal training on three Sextant modules
• Having a web browser (Mozilla Firefox, Google Chrome) update
• Ifremer Extranet account is not required for these exercises
SUMMARY
• GeoCatalogue …p1
• Geoviewer …p3
• Basket …p5

PART 1 : LE GEOCATALOGUE
Exercise 1 : Search data sets in GeoCatalogue – Simple selection criteria
• Start search on the GeoCatalogue without any keyword. How many results do you
get?
…………………………………………………………………………………………………...
Note: This is the total number of metadata visible to the general public.
• Start a new search with the keyword « Limanda limanda». How many results do you
get?
…………………………………………………………………………………………………...
• Launch a third search keeping keyword "Limanda limanda" by restricting the search
to a geographical extent covers an area from Southampton to Amiens. How many
results do you get?
…………………………………………………………………………………………………...
Searching informations in the metadata « Species and habitats - Limanda limanda - Eggs -
Stage 1- IBTS annual abundance in January 2006-2009».
• What are the geographic coordinates of this data extent?
………….....
………….… ………….…
………….....
• What is the contact name given in the metadata ?
…………………………………………………………………………………………………...
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Exercise 2 : Search data sets in GeoCatalogue – Advanced selection criteria
To access to all selection criteria,
simply click the "advanced" button
at the top right of the map. Now
you can refine your search by
selecting:
- A catalog,
- One or more thematic,
- A data producer,
- A creation date of the data
• Launch a search from all data contain in the "ATLAS_CHARM" catalog. How many
results do you get ?
…………………………………………………………………………………………………...
• Refine the search by limiting the list of records created between 1 January 2010 and
today's date. How many results do you get ?
…………………………………………………………………………………………………...
• On the results page, what metadata was updated most recently ?
…………………………………………………………………………………………………...
• For the latter issue, we want to know the number of metadata records dealing with the
theme « Nature des fonds» ?
…………………………………………………………………………………………………...
Export page results in PDF format.
Export metadata « Species and habitats - Sedimentary cover of the English Channel done
during recent surveys (1998-2007)» in PDF format.
Training exercices Sextant-CHARM Page 2/6

PART 2 : LE GEOVIEWER
Before adding data from the catalog, you can go to the tab GeoViewer to understand
the working of the tool.
By default, only the layer 'Continent' is present.
Note: The accuracy of the layer "Continent" adapts according to the zoom level.
Exercise 3 : Viewing data in Geoviewer
Now, you can add data from the catalog. Delete your previously search and add following
layers :
Vector data :
- “Physical environment - Sedimentary cover of the English Channel done by
Larsonneur and collaborators.”
- « Fishing activities - Scyliorhinus canicula (Lesser spotted dogfish, Small spotted
catshark) - Landings statistics (2000-2006)» Trimestre 4 – 4 th quarter
- “CHARM 1 and 2 official zones and CHARM 3 suggested zone” CHARM 3
Raster data :
- “Species and habitats - Ammodytidae - All ages - Presence probability in October
during CGFS (1988-2006)”
The four data layers are now added in the GeoViewer. Go to the tab GeoViewer and zoom to
the maximum extent of the site (if you're not already).
You can unfolded « Theme »
section to see the tematic tree.
Training exercices Sextant-CHARM Page 3/6

• Zoom to the extent of « Physical environment - Sedimentary cover of the English
Channel done by Larsonneur and collaborators ».
Clue : To avoid using the moving tools on the map, there is a shortcut in the "Layers".
• Keep only following layers in the map : « Continent » and « Physical environment -
Sedimentary cover of the English Channel done by Larsonneur and collaborators »
• What type of sedimentary facies is the yellow layer :« Physical environment -
Sedimentary cover of the English Channel done by Larsonneur and collaborators » ?
……………………………………………………………………………………………….......
• Modify style of « Continent » and choose orange color.
• Display data “ Fishing activities - Scyliorhinus canicula (Lesser spotted dogfish, Small
spotted catshark) - Landings statistics in tonnes (2000-2006) - 4 th quarter ”
• Change opacity and position the layer under “Continent” layer.
• Query layer in order to obtain attribute table
• Add data from CHARM WMS tool.
• Print your map. Give a title, some informations in the box "comments" and think
about increasing the quality of the output document.
• If you intend to work on your map later and in order to avoid having to reload the
layers one by one through the GeoCatalog, you must save the context of your map in
Xml file
• To understand the importance of this function, remove all layers of GeoViewer. Then
load the context file.
Training exercices Sextant-CHARM Page 4/6

PART 3 : THE BASKET
Exercise 4 : Download raster and vector data sets
As for GeoViewer, adding layers to download is from the catalog.
• Start the download for the following layers :
- “Physical environment - Sedimentary cover of the English Channel done by
Larsonneur and collaborators.”
- « Fishing activities - Scyliorhinus canicula (Lesser spotted dogfish, Small spotted
catshark) - Landings statistics (2000-2006)» Trimestre 4 – 4 th quarter
- “CHARM 1 and 2 official zones and CHARM 3 suggested zone” CHARM 3
- “Species and habitats - Ammodytidae - All ages - Presence probability in October
during CGFS (1988-2006)”
Once these operations are launched, go to the Basket tab :
Bloc 1
Bloc 2
Before clicking the download button, you can set the parameters extraction layers. Block 1 is
used to select these parameters for all layers while block 2 can do this work for each layer.
Training exercices Sextant-CHARM Page 5/6

• Choose Geographique - Datum WGS84 and ESRI Shapefile format for vector data
and TIF for raster data sets.
Note: Do not forget to click the button "Apply criteria"
• Modify coordinate system for « CHARM 1 and 2 official zones and CHARM 3
suggested zone (CHARM 3)» in European Terrestrial Reference System 1989, and
then start dowloading.
As you are not logged in with a Sextant account, a popup asking for your contact
opens. It was at this email address that you will receive an automatic message with a link to
download the data.
If no error occurs during the layers extraction, you will receive an email (example below)
15min later.
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