The Project Definitions window (opened from the File menu) allows users to view and edit the definitions associated with the currently opened projects. There are two ways to edit project definitions. First you can make changes to the definitions directly on the screen. Secondly you can right-click on any grid to display a context menu, which will in turn allow you to export/import the definition data to/from Excel. As with scenario properties, project definitions have a number of optional fields that can be displayed by right clicking on the context menu of the corresponding tabular editor.
Whenever you add a new definition, ST-Sim automatically generates a unique ID for the new record; these internal ID’s cannot be changed. Care should be taken when deleting a definition record, as ST-Sim will automatically find and remove any scenario property records that refer to the deleted definition.
A stratum in ST-Sim refers to a subset of the entire landscape being considered for analysis. Strata are typically used to divide the overall landscape into regions or zones, each of which can have different model parameters specified. Each stratum in ST-Sim is assigned a Name and optionally a Description. The Strata tab allows users to define the list of possible strata for a project. Two kinds of strata can be defined. Primary Strata (Vegetation Types by default) typically represent a biophysical or ecological stratification of the landscape. Secondary Strata (Planning Zones by default) typically represent a management stratification of the landscape such as ownership or jurisdictional boundaries. Both of these strata types can also have an optional ID defined. These ID values are used when running a spatially explicit simulation. In this case users must load an initial conditions raster for each of these strata types where the value of each cell corresponds to the ID values specified here.
Note that it is possible to change the terms vegetation type and planning zone for a particular project by editing the Terminology of the project definitions.
A fundamental building block of any state-and-transition model is the state class. In ST-Sim each state class is defined according to its unique combination of cover type and structural stage. The States tab allows users to define the list of possible cover types, structural stages and state classes for a project.
Each of the components of a state class (cover type and structural stage) has an optional description field. In addition, the state class definition has optional ID and Color fields. The ID values are used when running a spatially explicit simulation. In this case users must load an initial conditions state class raster where the value of each cell corresponds to the ID values specified here. The Color field (also for spatially explicit simulations) is used to define the legend color that will be used to display state class maps in the Results Viewer.
Note that it is possible to change the terms cover type and structural stage for a particular project by editing the Terminology of the project definitions.
The other fundamental building block of a state-and-transition model is the transition. ST-Sim recognizes both deterministic and probabilistic transitions between states.
Every state class in ST-Sim is allowed to have a single deterministic transition – these are configured for each scenario using Pathway Diagrams. The Transitions tab of the project definitions allows users to define the list of possible probabilistic transitions for a project. Probabilistic transitions are defined as Transition Types, which in turn can be organized into one or more Transition Groups using the Transition Types by Group definition. Transition Multiplier Types are used to define the different kinds of multipliers that can be applied against transition probabilities.
As with state classes, transition types have optional ID and Color fields, which can be used for spatially explicit simulations. In this case the Color field is used to define the legend color that will be used to display transition maps in the Results Viewer. The ID field is used to specify the ID for each transition type which will be used in output rasters for transitions when they are exported from ST-Sim.
The Transition Types by Group definition allows users to organize transition types into an unlimited number of transition groups. For example, the transition type Replacement Fire could belong multiple transition groups including: All Natural Transitions, All Fire and Replacement Fire. Various Scenario properties have a transition group field which allows users to specify parameter values according to each transition group.
The Transition Simulation Groups definition is an optional definition which is used for spatially explicit simulations. During a spatially explicit simulation, transition events are created according to the transition groups listed under Transition Simulation Groups. For example, for a transition group called All Fire (containing the transition types Replacement Fire, Mixed Fire and Surface Fire) an individual event can be a mosaic of each of the individual types it contains. For spatially explicit simulations it is recommended that each transition type belong to only one transition simulation group.
The Advanced Project Definitions tab includes a number of definitions which can be used alongside their corresponding advanced Scenario Properties. These include definitions related to Attributes and to Stocks and Flows.
The Terminology tab allows users to control the display text for the following:
- Amount Label field (by default Area)
- Amount Units for the Amount field (by default Acres)
- First label for State Classes (State Label X by default Cover Type)
- Second label for State Classes (State Label Y by default Structural Stage)
- Label for the Primary Stratum (by default Vegetation Type)
- Label for the Secondary Stratum (by default Planning Zone)