- Description tab
- Views tab
- Data Filters tab
- Data Selection tab
- Data Files tab
- Data Tables tab
- Expert Mode tab
- Source Bar
- Data Viewer
- Documentation tab
You should now be more comfortable with finding datasets in the Streaming Data Library (SDL). Let us take a closer look at the information and utilities available to you when you select a dataset. You will not use these utilities in this section, but it is important to know what they do and where they are for later parts of this tutorial. The Copernicus Land NDVI dataset is a commonly used dataset and is the example for this section.
Select the Copernicus Land NDVI* dataset.
When manually editing the ranges, just enter the limits in the respective fields under 'Setting Ranges', click on button 'Restrict Ranges', check the new settings for the grids under 'Data Selection' and if you are satisfied with the selection click button 'Stop Selecting'. If you want to edit the grid ranges interactively, click the link 'Data Viewer' shown near the top of the 'Data Selection' section. This will start the data viewer.
When in Expert Mode, the dataset in use is shown in the top 'Source' bar and beneath it a data selection bar and the command editor window currently containing the command equivalent of the current data selection. Commands can be added and/or edited in this window. When done, click the OK button and your commands will start being interpreted. Your view will return at the Description tab. The RESET button will take your command set back to the point when you started editing. The commands that can be entered comprise the SDL Scripting language, explained in short at the bottom of this page. The data selection bar shows the possible sub datasets or variables available to you. Right now, you should see only one main dataset 'Copernicus Land NDVI' with three sub-datasets being 'CRS', 'NDVI' and 'TIME_GRID'.
Because no variable has yet been selected, you can see all of the possible variables listed to the right of the data selection bar (here: longitude, latitude and time). Much more detail about expert mode, including specific examples, will be given in Parts II and III of the Tutorial.
We wil now explain a bit more about the Source Bar and the Data Viewer and the use of grids.
The source bar as depicted below, indicates to the user the location of the current dataset in the Streaming Data Library (SDL) and offers the opportunity to go to any of the higher levels in the hierarchy by selecting one of the links.
|SOURCES / Copernicus / Land / NDVI|
For example, you can view other Copernicus datasets by selecting the "Copernicus" link and available Land datasets by selecting the "Land" link. The source bar is an extremely valuable navigation tool in the SDL. Try using its options...
The data viewer is an interactive tool to manipulate the grids you use for your dataset and to change the way the data is visualized. It also enables you to select the format your imagery will be saved to. You could for example just want a link to a rendered image instead of downloading it to local storage. We will go over the options available here.
The data viewer can be accessed from the Data Selection tab with a data source having been selected. Near the top in the data viewer window the data source is shown together with the grid ranges in use and the grid type. Next, the main window is shown. At the center there is the rendered image obtained with the last applied settings. To the left and bottom of the image the grid ranges are shown for the vertical and horizontal grids in editable text boxes. Just above the image the time grid can be manipulated by editing the date range. To the left of the image three buttons are shown together with a zoom pulldown menu. Somewhat lower under the image the selected coloring range is shown which can also be changed to a user defined range. Under this some menus are shown with which you can alter the axes of the image, edit the drawing of land, sea or country contours and change the type of image being created. At the bottom of the page several options are available to obtain information on the selected data, to edit optional plotting settings for landscape marks as rivers, borders etc. and to export your image to a number of different formats. Many of these options will be treated in more detail in Parts II and III. For a quick help on all these options use the 'Help' button to the left of the image. The page will refresh with help information shown in the lower half of the page. After you have changed any of the variables in f.i. the text boxes you can refresh the image by clicking the 'Redraw' button to the left of the image. Using the middle 'Zoom' button one can zoom in or out of the image afer having selected one of the zoom levels from the pulldown menu. By just clicking in the image with the mouse, the image will be re-centered along the grid axes (if possuble). Another option worth noting here is the ability to animate over a range of dates. If the dataset is given a range of dates (in the textbox just above the image), a click on the Redraw button will start an animation, in fact looping over the results for the range of dates given. One can manually loop over the date range by clikcing the button(s) to the right of this textbox.
Just to get a feelng for it, a few examples to try:
You can think of grids as the ways in which
the data are dependent.
In this example, the data vary with latitude and longitude as well as with time. The information after each grid indicates the units and range of the grid. For example, the time grid shows the data taking interval and has data from Mar 26, 1998 through Oct 26, 2018 which creates 741 different time grid points. (Note: month is another common temporal grid unit.)
Grids vary from dataset to dataset, but there is a fundamental difference between those for gridded data and those for station data (i.e. data obtained at a single geographical point and pssibly multiple moments in time).
Select NOAA NCDC DAILY FSOD .PRES here.This is a dataset having a station grid. You can see this in the grid description showing the WBAN (Weather Bureau Army Navy) numbers as an ordered grid. If you click on the 'Data Selection' tab, a particular station or range of stations can be selected.
For additional information on grids, see this page.