| ODC Web Guide : Retrieval Panel |
|
|
The retrieval panel allows the user to navigate server directories, see the structure of the data, constrain the data query and output the data to one of various output options.
|
|
| Using the Retrieval Panel |
|
|
The retrieve panel looks like this:
When you click "To Retrieve" in one of the search panes (or double-click) the selected dataset will appear in the "Datasets" area of this screen (upper left). You can also add an URL manually by typing it in the "Location" bar at the top of the screen and pressing the "Add to List" button. If the URL points to a directory, the directory browser will become active in the lower left. In the screen shot above the user has selected a NASA MODIS directory and has drilled down into by double-clicking in the directory navigator. Note that many of the entries in the navigator have an ellipsis ("...") after them. That means that the directory has not been visited so the ODC does not know what they contain. The user must explicitly double-click a directory to see its contents. This action does a web hit. When a directory has been retrieved any files it contains will be shown in the list to the immediate right of the directory navigator. Double-clicking a file will cause its structure to be retrieved and shown in the "Additional Criteria" panel on the right. In the screenshot above you can see that the user has double-clicked on the file MO04MWN1.sst.ADD2001017.041.2003279195249.hdf.gz and its structure has been displayed. The file has a lot of variables in it, seven of which are visible in the Additional Criteria pane. |
|
| Selecting and Contraining Data |
|
|
Use the "Additional Criteria" panel located on the right to select and constrain the variables you want out of a given dataset. A dataset may have only one or many variables. The structure of OPeNDAP data is hierarchical, but the view shown in this panel lists each variable in a flat list. For example, in the screen above the variable "band_0" is inside a structure called "band" which itself is inside a structure called "Calibration".
Here the user has selected two variables "Grid" and "Grid.Data Fields.sst_mean". Note that the space in "Data Fields" shows as a "%20". This is an escape mechanism that will allow the request to be sent over the internet without the space interrupting request. The user has also sub-sampled the grid by picking a step of 5. This will return only every fifth value in each dimension (or every 25th value overall). By doing this the download has been made significantly smaller. You can see the size of download for grid and array variables after them in brackets. For example, in the screen shot above the download will be 5 megabytes. When the user is ready to output the data (here the output is set to the plotter) the "Output" button will be pressed. The View / Plotter panel will then automatically be activated and the data will be downloaded. |
|
OPeNDAP Data Connector Web Guide - Search ·
Revised 28 May 2004 ·
|
