====== Obtaining SAR Data ====== Syntheitc Aperture Radar (SAR) data is collected by a number of satellite systems operated by the European, Canadian, and Japanese space agencies. There are a number of online catalogues where one can search for the available scenes in a geographic area and check baselines. * [[http://eoli.esa.int/|EOLI]] * [[http://earth.esa.int/descw/|DESCW]] * others... Data can be purchased either directly from the space agency who owns the data, or through a data distributor. Those users whose university or research organization is a member of the [[sar#WInSAR|WInSAR Consortium]] can download data from a data archive. ===== EOLI ===== {{ eolisa_main.jpg?200}} [[http://eoli.esa.int/|EOLI-SA]] is a java application that allows users to access the satellite catalogues of the Europeans Space Agency (ESA). EOLI-SA can be downloaded at http://eoli.esa.int/geteolisa. Baseline information for interferometric pairs is only available on the java-enabled stand-alone application. === Begin a Search === {{ login.jpg?300}} Before you begin, make sure you are connected to ESA’s server. Click the green button in the upper left corner, connect as Anonymous user. If the button is red, you are already connected. 1. Each time you begin a session, you’ll need to add which collections you want to search. Click the //Add/Edit// button. In the left hand-panel, expand the menu for //Local Collections//. If the //Local Collections// check box is not appear, you may get the data base onto your computer by choose //App/Update all files// from the menu bar. You should see “1 Collection selected” next to the //Add/Edit// button. 2. In the //Collections// panel, select which collections you want to search. * For example, choose ERS SAR found under Local Collections. * Select //Interferometry// from the pull-down menu under query mode. 3. Now you are ready to parameterize your data search. Under the pull-down menu for //Choose a Date//, choose the range of your date. 4. You have multiple ways of specifying a geographic location. Enter the coordinates of your area of interest. Coordinates may be entered either as degrees, minutes, seconds format (dd:mm:ss) or as decimal degrees format (nnn.nn). Note that negative longitude is defined as west. Set your prefer height and width of the bounding box. 5. Search for perpendicular baselines within some range. Start with a narrow range (eg., 0 to 50 m); You can increase this range later to expand your search. 6. For the //Second Date//, choose //No Date// from the pull-down menu to prevent the conflicting criteria. 7. Check the satellite, pass type boxes for your choices, and complete the range of orbit, track and frame range. Check the //Archived// box. Repeat this step farther down the page. === Search results === The results are presented in 3 different ways: in a table, on the map, and as thumbnail images (if existing). {{ table.png?400 }} * At the bottom of the page, click on the Detail button {{detailed_button.png|}} to view the detailed information and see the full size browse image of selected item. * Click on the Export button {{export.png|}} to export the interferometric search results. The exports data are present in a comma separated ascii text file as CSV, XML, HTML and UserSet formats. //For further information, the EOLI-SA manual can be downloaded at// http://www.tiger.esa.int/trainingcd/content_4/EoliSA-Manual.pdf. ===== WInSAR ===== The **W**estern North America **In**terferometric **S**ynthetic **A**perture **R**adar (WInSAR) Consortium provides SAR data for scientific and educational purposes. The consortium has an open data policy among participants. Data coverage is primarily limited to the western United States. Access to the data is restricted to member institutions. Data can be ordered and downloaded from one of several [[http://winsar.unavco.org|portals]].