The EverVIEW NetCDF Slice and Dice Tool allows the user to create a subset of a NetCDF file using multiple constraints. Available constraints include time, spatial (features from a shapefile, bounding box, or list of points), and data ranges. The methods of specifying these constraints is explained in the respective sections of this manual. As the tabs of the tool are navigated, some fields will be required to continue to the next step in the process. Once all the tabs are completed, the review tab will give an overview of the parameters the program will use to create the subset NetCDF file. If the parameters are correct, the export button can be used to create the subset. If there is a problem with the parameters, then either use the back button to return to a previous tab, or any previous tab can be clicked directly. Any errors encountered during subset file creation will be indicated in a popup error window.
1. Navigation buttons at the lower right of the program allow navigation between sections of the tool, as well as the ability to quit the process at any time.
2. The Help menu at the top of the window allows access to this document, information about the current version of the software, and a mechanism to check for updates to this software.
3. Note that on some screens, required fields must be filled in before the process can continue.
Figure 1 – Using the EverVIEW NetCDF Slice and Dice Tool
The open tab allows the user to specify which NetCDF file to use as input for the subsetting process, and which file to use to store the output. The view button can be used to examine the chosen NetCDF input file in the table viewer, which shows the data values from the file in a spreadsheet format, with options to choose a grid and time variable to view.
1. To begin the process, select the file you want to subset. This can be done by either clicking the “Browse…” button then selecting a file, or by manually typing the path to the file in and pressing the “Enter” key on the keyboard.
2. Once the file to subset has been specified, the destination file path will be automatically filled in. This path can be modified if a path other than the default path is desired, which is the name of the file selected prefixed with “subset_”.
3. Note that after selecting the file to subset, the “File Information” icon in the upper right can be clicked to view a basic description the NetCDF contents.
4.
The “View” button can also be clicked to view data from within the
selected NetCDF file.
IMPORTANT BATCHING INFORMATION :
Clicking the "Add More" button will allow for
batching of files. This speeds up the process of putting the same
filters across multiple files .To do so, add additional files
by clicking the add Input File to add specified input file.
1. If any of the files included in the batching
contains dates outside of the first input file chosen then this file
will not be used and an error
message will be shown to indicate so.
2. If the time range of a batch file doesn't meet the time constraints used (for example, the primary file has one year of data and a batch file has only one quarter), an error will occur.
3. If the spatial footprint differs such that spatial constraints would conflict with a batch file (for example, if the initial input dataset resides in Florida and a dataset from Louisiana is included in the batch list) , an error would occur.
5. The “Next” button can be clicked after specifying the input and output files to move to the next tab.
Figure 2 – The Data tab in the EverVIEW NetCDF Slice and Dice Tool.
Figure 3 – The Data tab in the EverVIEW NetCDF Slice and Dice Tool with batching enabled.
The Data Series tab allows the user to select which grid or grids from the NetCDF file to subset. Only the selected grids will be subset and included in the output file. Multiple grids can be selected, but only 2 and 3 dimensional grids will be shown for this version of the software.
1. Select a grid to subset. Only two (x,y) and three (x,y,time) dimensional grids are shown.
2. Note that you can select more than one grid by holding down the Control key on your keyboard while clicking the grids to subset. Click the “Next” button when you are done with selecting grids.
Figure 4 – The Data Series tab in the EverVIEW NetCDF Slice and Dice Tool.
The Date/Time constraints tab allows the user to filter output data based on time. This filtering can be applied two ways: limiting the total valid range of time, and adding seasonal filters. The total valid range of time is specified by a valid start and end date. Any time inside these bounds, including the bounds themselves, will be considered valid. Seasonal filtering will be applied to all valid times in the total valid time range. Seasonal Filtering is optional and is not required to create a NetCDF subset. Seasonal filtering can be specified by a valid time range, or by an entire month. Multiple filters of either type may be added to the filter list. The filter list can be saved to and loaded from an XML file.
1. Select a start time and end time from the start and end time combo boxes in the Time Range section. This will select the range of times to use in the subset.
2. Select a start and end date from the start and end date combo boxes in the Filtering section to specify a range of valid dates to use in the subset. Click Add to add the date range to the filter list. This action can be repeated to create multiple filters.
3. Select a month from the month combo box in the Filtering section to specify a valid month to use in the subset. Click add to add the month to the filter list. This action can be repeated to create multiple filters.
4. The load and save buttons can be used to load or save the filter list. Load will load the contents of a previously saved filter list into the current filter list from an XML file, and save will save the contents of the current filter list to an XML file.
5. When configuration of the time range and filter list is finished, press the next button to continue to the next tab.
Figure 5 – The Date/Time Constraints tab in the NetCDF Slice and Dice Tool.
The Data Value Constraints tab allows the user to filter the output data based on the data values. This section is optional and is not required to create a NetCDF subset. Each filter takes the form of an upper and lower bound, with the values between the two being the valid range and the upper and lower values being inclusive. Multiple filters can be created for one exported NetCDF file as long as the ranges of the filters do not overlap. The created ranges can be saved to and loaded from an XML file.
1. Enter a number into the Lower Range text box to specify the lower range of the data value filter
2. Enter a number into the Upper Range text box to specify the upper range of the data value filter
3. Press the Add button to add the data value filter to the filter list.
4. Repeat steps 1 through 3 to create multiple filters if required.
5. The load and save buttons can be used to load or save the filter list. Load will load the contents of a previously saved filter list into the current filter list from an XML file, and save will save the contents of the current filter list to an XML file.
6. When configuration of the data value filter list is finished, press the next button to continue to the next tab.
The spatial constraints tab allows the user to constrain the output of the subset NetCDF file based on shapes in an ESRI Shapefile, user specified bounding coordinates, or points loaded from a text file. This section is optional and is not required to create a NetCDF subset. WARNING: The spatial subset operation cannot ensure accuracy if the coordinate variables are not monotonic (either always increasing or decreasing) as specified by the CF Standard."
1. Choose the desired type of spatial constraint by clicking one of the radio buttons at the top of the tab. Choose Shapefile to create a subset based on features extracted from an ESRI Shapefile. Choose Coordinates to enter the corner points that will be used to create a rectangular subset. Choose Point File to load points from a text file and create a subset containing only the grids that match up with specific points.
2. Shapefile: Press the Browse button to open a shapefile (shp)
3. Select an item from the attribute drop down box to populate the shape list to the right
4. Select items from the shape list to create a subset containing only grid centers that are contained within the feature polygons. In order to choose multiple features (based on attributes in the file such as ID, Area, Perimeter, etc), hold the Ctrl key while making selections. NEW in version 2.1: Shapefile polyline and point features can be used to generate spatial subsets. These features will be buffered by max 1/2 grid height or width for testing against grid points. Grid centers that fall within the buffered region(s) will be included in the output dataset.
5. If the program is unable to determine the coordinate reference system (CRS) that orients the features within the shapefile, then it will indicate this with a warning and show a popup window to allow the user to specify it manually. Either select a CRS from the drop down menu or enter a custom EPSG code (ex. EPSG:4326) into the text box. Save your selection by clicking the button at the bottom of the popup. If additional information is needed regarding EPSG codes or the terms in the drop down box, visit the Spatial Reference website.
6. Coordinates: Enter the minimum and maximum values for the corners of the bounding box in the corresponding text boxes.
7. Point File: In order to include only grids that match up with a list of points in 2 dimensional space, a point file panel is available. To load a point file, press the Browse button and select a text file formatted with comma separated values (csv). The first line of the file must contain header information that is used to identify which columns to assign as X and Y coordinates. If the file satisfies this requirement, a popup window will open. Select the columns to use for X and Y coordinates, and select a coordinate reference system (CRS) that helps align the points to the NetCDF grid. Either select a CRS from the drop down menu or enter a custom EPSG code (ex. EPSG:4326) into the text box. Save your selection by clicking the button at the bottom of the popup. If additional information is needed regarding EPSG codes or the terms in the drop down box, visit the Spatial Reference website.
8. EverVIEW Identify Object / Google Earth KML/KMZ: Load a Identify Object XML or KML file from EverView, or a saved places file from Google Earth. This feature allows for saved objects to be selected and used to constrain the given dataset. After selecting the EverVIEW Identify Objects File / Google Earth KML/KMZ button to begin, select the desired XML/KML Object list. A table will then show all of the pbjects present in the file. All of them are selected by default, but can choose any of the objects that you wish. Other Notes related to the actual files being loaded, the size limit of Identify Object file in EverVIEW depends on the user prefrence of the maximum number of Identify Objects allowed at one time. Google Earth restricts the number places to be saved by a file size limit of 10MB.
Figure 6 –Selecting the Identify Objects from the table.
9. When configuration of the Spatial Constraints tab is complete, press the Next button to continue to the next tab.
Figure 7 –The shapefile selection in the Spatial Constraints tab.
The review tab gives a summary of the settings chosen to create the NetCDF subset. It lists the user's choices for each category in an expandable section. If the information is correct, the export button can be pressed to create a new subset file from the chosen NetCDF based on the listed constraints.
1. Review the setting presented in the various sections of the Review tab list. If there are incorrect settings, then click on the corresponding tab to navigate back to that tab to correct the problem. Click on the review tab when the corrections are complete.
2. When all settings are correct, press the Export button in the lower right corner to begin exporting the subset NetCDF file. The progress of the export will be indicated on the status bar at the bottom right of the window.
3. When the process reaches 100% a message will pop up indicating the process was successful. The export is now complete. Click OK.
4. A table viewer tab will now open to view the subset NetCDF file. You may browse the data in the grid using the scroll bars, change the grid or date using the indicated combo boxes, or change the file by using the Browse button and selecting the desired file.
5. You may now either close the program by clicking on the X at the top right of the window, or close the table viewer tab by clicking on the X on the table viewer tab.
6. You may begin another subset process by clicking on the open tab and performing the process over again.
Figure 8 – The Review Tab.