SMS:Converting Feature Objects

Map Module
Map
Feature Objects
Coverages
More
Map Module Interface
Map Display Options
Map Module Tools
Feature Objects Menu
Map Project Explorer

Feature objects can be converted to other data types in SMS such as meshes, grids, scatter sets and cross sections. This can be accomplished by either right-clicking on a coverage in the project explorer and selecting a convert command or by selecting the following commands from the Feature Objects menu:

Map → 2D Grid

The Map → 2D Grid command is used to create a 2D grid using the feature objects in a 2D Grid Coverage. When the Map → 2D Grid command is selected, the Create Grid dialog appears. A grid frame must have been defined. The size and location of the grid frame are used to initialize the fields in the Create Grid dialog. In most cases, these values will not need to be changed and the user can simply select the OK button to create the grid. If a grid frame has not been defined, the size and location of the grid are initialized so that the grid just surrounds the currently defined feature objects. If desired, the grid dimensions can be edited prior to selecting the OK button to create the grid.

Grid Frame Properties

The grid frame properties dialog allows the user to specify the attributes applied to the grid frame when performing a "Map → 2D Grid" operation. These properties are as follows:

• Origin
• Orientation
• Directional properties (u and v direction)
  • Define cell sizes – specified uniform cell sizes
    • Cell size – the cell size in the specified direction
    • Number of cells – number of cells in the specified direction
  • Use refine points – refine points will be used to generate the grid
    • Maximum cell size – the max size the should exists when growing
    • Maximum bias – the max growth ratio to be used when growing
    • Use inner growth – specifies whether the cell sizes should grow between two refine points
  • Grid size – the grid dimension in the specified direction

When the user specifies "Define cell sizes", there are a few options available. These options are:

1. Specify cell size – specify the cell size and the number of cells will be computed.
2. Specify number of cells – specify the number of cells and the cell size will be computed.

If the grid is to have square cells, the v direction cell size will always be linked to the u direction cell size.

Refine Points

Refine points for a Cartesian Grid allow a user to change the cell dimensions when generating the grid. They are not available for all models, since some Cartesian Grid models require uniform cell sizes. The user can specify whether to refine in the I and/or J direction and the base cell size for each direction.

When the refining is performed, the base size may be changed in order to fit the other restrictions applied to the refining process. If two refine points are too close to each other to allow the cell size to transition, one will be ignored when generating the grid. See Refine Point Dialog for more information.

Depth and Vector Options

In addition to the options specified on the grid frame, depth and vector interpolation options can be specified during the mapping process for some models. The depth mapping is required for all models, while the vector mapping is optional even for the models it can be performed on. Depth and vector data sets can be constant or interpolated from a scatter set.

Cells a user specified tolerance above the datum can be marked as land (inactive) cells. This option is on by default for BOUSS-2D, but defaults to off for other models.

When specifying a constant vector, the X and Y components are oriented based on global space, not grid space.

The name of the vector dataset can be specified, but the name of the depth dataset is always set to "Depth".