HEC-MetVue Model Alternative
HEC-MetVue Project File and Directory Structure
Settings within a HEC-MetVue Project file provide the base information for developing HEC-MetVue Model Alternatives in the. HEC-MetVue Project files follow the hierarchy Project > Sessions > Map Panels. Projects contain global settings. Sessions are synonymous with Model Alternatives in the context of the CAVI (i.e. any Session in the Project file is also a Model Alternative in the Setup Module of the CAVI). Map Panels house settings for the Input Data and Basin Average Maps.
Each watershed has a single HEC-MetVue Project, which contains one or more Sessions (each corresponding to a CAVI Model Alternative). Each Session should contain at least one Map Panel, and the Map Panels within the Session will perform the data processing functions necessary for a forecast run. Since HEC-MetVue is a hydro-meteorological data processor, it will likely need to process data for the Lookback and Forecast time windows separately. Therefore, creation of a Lookback and a Forecast Map Panel for each dataset will likely be required. After creation of these Map Panels, each should be loaded with input data that matches the data extract, and any necessary basin average maps added.
If not already present in the Watershed directory, HEC-MetVue will create the directory ./watershed/MetVue to house its settings when opening a Watershed. Additionally, a Project file matching the Watershed’s name will be created and opened, and a maps sub-directory will be created to house the basin average maps. The ./watershed/MetVue directory will also contain the HEC-MetVue Model Alternative files once they are created (with the .mvalt extension ), which contains information about input file/paths, and output data to create.
For further information on how to create . For an example on setting up a Project File for using in the CAVI, see the document.
Importing Existing HEC-MetVue Project
Importing of existing Project files may be performed if the user has a pre-built project file with all the desired settings. During the import, each Session within the Project File will be converted into a Model Alternative. Through this process, the Project file will be copied into the ./watershed/MetVue directory with a file name matching the watershed. All basin average maps will be copied into the ./watershed/MetVue/maps directory, and all map files will become relatively pathed within the Project File. This will make the maps available for computes within the CAVI. Although maps are copied into the watershed directory, no HEC-MetVue data is copied. Copying of HEC-MetVue data is avoided because it is potentially very large, and will likely be replaced through the extract process. Finally, a HEC-MetVue Model Alternative file will be created (with the .mvalt extension) for each Session within the Project file. Within each Model Alternative file, each Map Panel in the corresponding Session will have an input data type and input file/path, which is parsed from the settings in the Project file.
To import a MetVue Project File:
- Select the MetVue icon in the Setup module by right-clicking on it and selecting Import (Figure 1). This will bring up the Open MetVue Project File dialog.
- Select the Project file you would like to import and click the Open button on the file selector. This will copy the selected Project File into the ./watershed/MetVue directory and any map files into the ./watershed/MetVue/maps directory within the watershed directory.
Creating Model Alternatives
HEC-MetVue supports the addition and deletion of Sessions and Map Panels in Watershed’s Project file. This allows for development of Model Alternatives within the automatically generated or imported Project file. This can be performed by launching the HEC-MetVue application from the rain drop button in the CAVI, then performing the necessary edits in the project tree. Once edits are completed, HEC-MetVue can be closed, and clicking on the HEC-MetVue node in the Setup Tab will refresh the Sessions and Map Panels. If Sessions were added, those will show up as new Model Alternatives. If Map Panels were added, those will show up in the MetVue Alternative Editor for the given Model Alternative. Similar to the Import process, a Model Alternative file will be created for each Session created in the Project file, and that Model Alternative file will contain the input data type and input file/path information. As opposed to the Import process, the basin average maps will not be copied, and therefore it is recommended that all basin average maps are placed in the ./watershed/MetVue/maps directory, and relative pathing turned on.
Editing HEC-MetVue Model Alternatives
HEC-MetVue Model Alternatives can be edited by right clicking on the alternative node and selecting Edit Alternative…. This brings up the MetVue Alternative Editor dialog. The editor has two tabs, Input Settings and Output settings, as shown in Figure 3 and Figure 4, respectively.
The Input Settings tab identifies the Map Panels that will be used in the Forecast. In each row of the table, the user can specify if a Map Panel applies to the Lookback, Forecast, or both time windows, which controls the time window that the Map Panel is asked to load data within the Modeling Tab. These are selected with the checkboxes in the table. Each Map Panel that will be used in a forecast must have at least one time window selected.
The Basin Average Maps are used for computing basin average time series, and are reported in this editor. Editing the basin average maps must be performed on each Map Panel in the HEC-MetVue application. Changes to the Basin Average Maps performed in the HEC-MetVue application will be appear in the MetVue Alternative Editor after closing and reopening the editor. When the mouse pointer is hovered over a row in this table, the absolute path of the basin average map file is presented for verification purposes.
The Input Data section allows you to select the type of TIN/Grid Input (i.e. DSS, File, or MetVue Interp), selection criteria for the input type, and specify your interval. The three options are summarized below:
| DSS | Selecting the DSS option as the TIN/Grid Input allows you to see the pathname selection fields. These fields may be populated by manually entering text, or clicking the Browse… button and selecting a record in an existing DSS file. These settings will be used to select the pathname from the forecast.dss file based on the a, b, c, and f part, and the input duration. |
| File | Selecting the File option as the TIN/Grid Input allows you to select input files based on filename patterns and duration filtering. |
| MetVue Interp | Selecting the MetVue Interp option as the TIN/Grid Input allows specification of a MetVue Interp file (similar to Gage Interp). This allows you to specify the input data from point time series, which will then be interpolated onto a grid. |
The TIN/Grid Input will be filled automatically with the MetVue Map Panel read settings during the import process, but may require additional editing if the read settings are incomplete/incorrect. It is important to verify that each Map Panel TIN/Grid Input matches the desired input data source. Additionally, any DSS paths are assumed to be located in the forecast.dss file once a forecast is created. The File and MetVue Interp options should be relatively pathed to ensure proper loading when in the forecast module.
Once the proper input data for each Map Panel used in the alternative is selected, the Output Settings may be specified as shown in Figure 4.
The Output Settings tab in the MetVue Alternative Editor contains sections to specify the output datasets, including the output dataset name, output time interval, and three possible output data types: Gridded Data File Generation, DSS Grid Outputs, and Time Series Generation.
The Output Data Selection table is located at the top of the Output Settings tab. This allows you to identify an output dataset, and assign the Map Panels that will provide the lookback and forecast input data. The “Lookback Map Panel” column combo-box will be populated with the Map Panels specified for the lookback time window in the input settings, and the “Forecast Map Panel” column combo-box will be populated with the Map Panels specified for the forecast time window in the input settings. If a single Map Panel will be used for both the lookback and forecast, then that Map Panel needs to have both time windows selected in the Input Settings tab. Each dataset needs to have a Name, Parameter and Unit specified, which determines how the output metadata will be written.
The Output Time Interval is used to specify the time interval that the downstream model requires. As shown in Figure 4, a 1-Hour dataset is going to be generated. If the input and output time intervals do not match, HEC-MetVue will aggregate/disaggregate/interpolate data from the input time interval to the output time interval. Additionally, the Output Parameter Type may be altered. This will most like be PER-CUM for precipitation, and PER-AVG or INST-VAL for temperature.
The Output Extents panel allows for defining the spatial extents of the output data, based on a shapefile. This ensures that HEC-MetVue is not creating unnecessarily large grids.
The three types of output data – Gridded Data File Generation, DSS Grid Outputs, and Time Series Generation – can be specified below the Output Settings and Output Extents. While all three types of output data may be generated in a single forecast run, it is advised that you only select necessary data. This is because each output data type requires additional computation time and space within the forecast.dss.
| Gridded Data | The Gridded Data File Generation option is the first of the three output data options that the user can modify. It allows for the specification of saving projected data to any gridded file output supported by HEC-MetVue. This option requires specification of the Write Provider, the projection of the output grid, and the output filename. Custom projection information can also be specified via the Add/Edit button. |
| DSS Grid | DSS Grid Outputs options are located directly underneath the Gridded Data File Generation section. These options allow the user to specify the record pathname to save the output data into, and these records will be saved into the forecast.dss file. These settings also allow the user to specify that the output should be in SHG or HRAP projection. |
| Time Series | The Time Series Generation section is the last output data selection on the Output Settings tab. This option specifies if basin average time series will be generated, and allows for selection of the Sub-basin Name Column within the shapefiles, which is required for identifying the output pathname. |
For most applications, it’s expected that either DSS Grid Outputs, or Time Series Generation to DSS will be used, so that the data can be passed to HEC-HMS. For Time Series Generation, the default selection is “Name” for the Sub-Basin Name Column combo-box. That is the column in the shapefile that is expected to correspond to the HEC-HMS sub-basin name. If using Time Series Generation for a watershed in a Time Zone other than GMT, refer to Important HEC-MetVue Application Settings for additional considerations.
If there are any errors with the setup in this panel, the Warnings text box located at the bottom of the Output Settings will contain notifications about what needs to be changed.
Forecasts Using HEC-MetVue
When a forecast that contains a HEC-MetVue Model Alternative is opened or created, that alternative will be displayed in the forecast tree under the Modeling tab. This HEC-MetVue Model Alternative has its own project file, which is located in the ./forecast/MetVue/ directory. Any changes to the HEC-MetVue settings will be performed on this project file, and can later be copied to the watershed project file with the Save To Base action. Each Map Panel in the alternative has its own node under the Model Alternative node. When a Forecast is first opened, the data for each Map Panel will be extracted and loaded into the Map Panel. The data is also reloaded after subsequent data extractions.
Through the process of loading the data into each Map Panel, HEC-MetVue reads data based on the specifications in the Input Settings tab of the Alternative Editor, and converts them to a Triangulated Irregular Network (TIN). As a TIN, HEC-MetVue can display and edit the data spatially, on a per Map Panel basis. Initiating the display is performed by selecting a Map Panel node, as shown in Figure 5.
If a Map Panel node is selected, the Actions panel below the forecast tree is populated with the following action buttons:
The first button is the Refresh TIN Data button, which reloads data into the Map Panel based on the TIN/Grid Input settings in the Model Alternative. The second button is the Edit Display Options button, which allows the user to change display settings of the data, and is further described below. Next is the Edit MetVue Options, which launches a dialog providing access to HEC-MetVue options. Changes to this dialog will update the display of any HEC-MetVue TIN in the CAVI Map Panel. The following five buttons provided the ability to edit TIN data loaded into the Map Panel: Calibrate TIN, Transform TIN, Modify TIN Z Values, Undo, Redo, which are described further below. Additionally, there is an Animate Images button, which launches the HEC-MetVue animation dialog. Finally, there are three options to save data loaded into the Map Panel: Hyetograph Surface Creation, Save Projected TIN Data, and Save TIN Data, which are further described below.
Data Status Tracking
The Map Panel icon will change color to track the state of a TIN, which are summarized in
Table 1 - TIN Status Icons
Icon | TIN Status |
| Data loaded properly without a need for preprocessing |
| Data was preprocessed to apply necessary transformation and/or data filling |
| Data failed to load |
| Data has user edits |
| Data has been computed |
HEC-MetVue Display Settings
HEC-MetVue display information can be adjusted in any Map Window where HEC-MetVue information is displayed. Display adjustments can be made by clicking on the Edit Display Options button, which will bring up the Display Options Editor dialog as shown below in Figure 6.
The Display Options Editor allows the user to set the level of transparency for the HEC-MetVue image and set options for displaying the Legend.
- Transparency is the first editable Display Option. To set the transparency, enter a number between 0 (opaque) and 1 (completely transparent).
- The Legend can be shown by selecting the Show Legend The dropdown menu is used to pick the location where the Legend will display.
After to the display options are complete, click the Apply Changes button at the bottom of the dialog. This will redraw the MetVue options with the entered settings.
The HEC-MetVue application settings can also be edited by clicking the Edit MetVue Options button. This brings up the HEC-MetVue application settings, as shown in Figure 7. All settings applied within this dialog will immediately be applied to the selected HEC-MetVue Map Panel, and will updated the display in the CAVI Map Panel if they affect TIN displays.
HEC-MetVue TIN Edit Actions
TIN data edits can be performed on a per-Map Panel basis. Edits performed are stored in memory until the data is reloaded (reverts all changes) or a compute is performed. If a compute is performed after making edits, the computed data will reflect those edits. For example, if the user scales the data by a factor of 2, then computes, the output data will be 2 times greater. Below is a list of the possible TIN edit actions provided by HEC-MetVue within the CAVI.
HEC-MetVue provides a tool to calibrate spatial data based on ground observations. This was originally developed for radar calibration, but can be applied to any spatial dataset. Calibration of spatial data can be performed from within the CAVI by clicking the Calibrate TIN button. This will bring up the TIN Calibration Dialog, shown in Figure 8. Due to the complexity of this tool, users are referred to the HEC-MetVue user’s manual for details of TIN calibration spatial data with HEC-MetVue.
HEC-MetVue allows you to translate and rotate the TIN data spatially, for the purposes of changing a storm location or its orientation with respect to a basin. Although standalone HEC-MetVue allows you to do this interactively by dragging data across the screen, these operations are only possible within the CAVI through text inputs. To make changes directly using mouse interaction, the HEC-MetVue User Interface can be launched, and edits can be performed.
In order to start transforming a TIN within the CAVI, click the Transform TIN button to open the TIN Transformation Editor dialog, as shown in Figure 9. The editor is broken down into different sections based on whether you want to modify the Transformation Units, Spatial Translation, or Rotation.
- The Distance units can be changed by selecting an option from the dropdown menu. It is found in the top of the Transformation Units section at the top of the dialog.
- The Angle can be changed by using the dropdown menu directly underneath the Distance options, in the Transformation Units section of the dialog. In addition, the desired Translation or Rotation can be selected by selecting the corresponding radio button. Translation and rotation must occur in separate operations in order to prevent confusion on which operation is meant to occur first.
- Cartesian Translation can be specified in the Spatial Translation section of the dialog. The X Distance and Y Distance should be entered in the units specified earlier in the Distance section of the Transformation Units.
- Polar Translation is used to translated the TIN based on an angle and distance. To perform a polar translation, select the Polar Translation radio button. Angle From North (clockwise) and Distance can then be entered in the units specified above in the Transformation Units
- Rotation can be performed by selecting the Rotation radio button in the Transformation Units section, and specifying an angle (clockwise) to rotate the storm.
After TIN edits have been entered, click the Apply button at the button of the TIN Transformation Editor to perform the operation. Directly to the left of the Apply button is the Undo button. Directly to the right of the Apply button is the Redo button. Clicking these buttons will alter the location or orientation of the storm, and the image in the CAVI Map Panel will be updated.
HEC-MetVue also allows modification of the TIN measurement values. This can be performed by clicking the Modify TIN Z Values button which brings up the Modify TIN Measurement Values dialog shown in Figure 10. This dialog allows for multiplying the whole TIN by a constant, adding a constant value to the entire TIN, or setting the entire TIN to a specific value.
In addition to the edit actions above, Undo and Redo buttons are provided. These allow for quickly reverting unwanted changes, or reimplementing changes.
HEC-MetVue has edit tracking, which checks if data within a Map Panel has been edited. When run as a standalone application, HEC-MetVue will prompt the user with the option to save data prior to closing any Map Panel, Session or Project where edited data exists. When connected to the CAVI, HEC-MetVue suppresses this prompt, and therefore any edits will be discarded upon close of a forecast. This is necessary to prevent an HEC-MetVue save prompt from interrupting the CAVI workflow.
HEC-MetVue Application Interaction
As opposed to editing HEC-MetVue data within the CAVI, it’s possible to open the HEC-MetVue application and perform edits. This can be performed by clicking the rain drop button (
), which shows the HEC-MetVue application. Within the application, each Map Panel will reflect the state shown in the CAVI, and allow for further edits to the TIN data. As edits are performed in the HEC-MetVue application, the CAVI display is continually updated. This keeps the state of HEC-MetVue and CAVI synchronized, allowing for editing in real-time. Editing within HEC-MetVue is particularly convenient for storm translation and rotation, which can be performed interactively with mouse dragging. For more information on TIN data editing within the HEC-MetVue application, consults the HEC-MetVue application documentation.
Data Save Actions
Beyond the data saving that occurs during a HEC-MetVue compute within the CAVI, three options are provided for saving data: Hyetograph Surface Creation, Save Projected TIN Data, and Save TIN Data.
The Hyetograph Surface Creation tool allows for generating a series of TIN/Grids, based on data loaded within a Map Panel. The primary purpose of this tool is to allow manipulation of the temporal distribution of precipitation, by using either synthetic patterns or observed hyetographs. After clicking this button, the Hyetograph Surface Creation dialog will be shown, as displayed in Figure 11. Due to the complexity of this tool, the user is referred to the HEC-MetVue user’s manual for details about its functionality.
Save Projected TIN Data provides a tool to project data into a new resolution and coordinate system. Clicking this button will bring up the Project TIN(s) to a Grid dialog, shown in Figure 12. This dialog allows for specification of the file type to save to (“Save to:” combo-box). After selecting a save type, the projection information can be specified, based on the projections that the save type can support. Therefore, available settings will change based on the save type. Regardless of save type, the Target Extents will be available to edit. For save types that support multiple projections, the Projection Coordinate System can be selected. Finally, the output file information can be specified in this dialog. After clicking OK, the file will be saved, and the user can continue with the forecast.
The Save TIN Data button launches the Save TIN(s) dialog (Figure 13). This dialog provides an additional tool to save data, either saving the data as an aggregate TIN/Grid, or applying the changes to each base TIN and saving. Since there is no projection, only the save types that support the current Map Panel projection can be selected. Following the selection of the save type, the aggregate and/or base TIN save file paths can be selected. Three additional write constraints can be selected: Write time zone, output units and time shifting. After specification of the desired save settings, clicking OK will save the specified data.
Important HEC-MetVue Application Settings
- The read and write constraints must be set from within the HEC-MetVue application as they cannot be set from within the CAVI.
- If the TIN is not going to be rotated or translated spatially, the spatial extent read constraint should be set within the appropriate read dialog.
- Trimming the spatial extents if there is no need to have data outside of the sub-basin boundaries on read can improve both the display performance and computation speed when forecasting.
- When writing to sub-basin time series with a watershed in a time zone other than GMT, the time zone write constraint should be specified within the basin average time series save dialog. This will ensure proper reading of the data from the following model in the compute sequence.
HEC-MetVue Compute Process
Standalone HEC-MetVue does not have a compute. It has many different tools for loading, manipulating and saving data. Therefore, using HEC-MetVue within the CAVI requires a special compute engine, which links these operations together. The compute process is four steps: Data loading, data editing, temporal transformation, data saving. Data loading and editing were covered in in earlier sections. Temporal transformation changes the time-step of the data to match the forecast time-step, and appropriately changes the Data Type (INST-VAL, PER-AVER, or PER-CUM). Depending on the input Data Type, and the transformation being performed, data will be interpolated, disaggregated, average or summed to get the appropriate value for each forecast time-step. Following the temporal transformation, the data will be saved to the specified output data type. In the event that basin average time series are being created, saving will involve an additional step of computing the spatially averaged time series for each modeling sub-basin.