User's Reference - Regrid

### Regrid

Category

Realization

Function

Maps scattered points onto a grid.

Syntax

    output = Regrid(input, grid, nearest, radius, exponent, missing);

Inputs

Name | Type | Default | Description
--- | --- | --- | ---
`input` | field or vector list | none | field with positions to regrid
`grid` | field | none | grid to be used as template
`nearest` | integer or string | 1 | number of nearest neighbors to use
`radius` | scalar or string | "infinity" | radius from grid point
`exponent` | scalar | 1.0 | weighting exponent
`missing` | value | no default | missing value to be inserted if necessary

Outputs

Name | Type | Description
--- | --- | ---
`output` | field | regridded field

Functional Details

This module uses a specified set of scattered points (`input`) to assign data values to every position of a specified grid.

`input` | should be either (1) a field with a 1-, 2-, or 3-dimensional "positions" component or (2) a list of 1-, 2-, or 3-dimensional vectors. In the second case, the vectors are interpreted as positions.
`grid` | is required. It specifies the grid to be used as a base for creating a "connections" component. The dimensionality of positions in this grid must match that of the positions in `input`. The specified `grid` could be created with the Construct module.
`nearest` | must be an integer or the string "infinity." An integer value specifies the number of nearest points (to each grid point) to be used in computing an average data value for that grid point.
`radius` | specifies the maximum radius (from the grid point) within which the nearest neighbors can be found. The parameter must specify a scalar value or the string "infinity." if 0, will place the data on the nearest grid point. If more than 1 data values lie within 1/2 delta of a grid point, then the average value will be computed. (Very fast)
`exponent` | The averaging method is a weighted average. The expression for this average is 1/radius`(exponent)`. The default value is 1.0, reducing the expression to the reciprocal of the radius.
`missing` | is used when `radius` is set to a value other than "infinity." The parameter specifies how to treat those grid points for which no points in `input` occur within the specified radius. If `missing` is not set, the module creates an "invalid positions" component, and grid points with no assigned data value are invalidated. If `missing` is set, the data value is inserted for the missing data values. It must match the data component of `input` in rank, type, and shape. All components that are position-dependent are treated in the same way as the "data" component.

Note: To remove invalidated positions, use the Include module. However, it is not necessary to remove invalidated positions in order to have them treated as invalid by other modules.

Components

Adds a "connections" component. The "positions" and "connections" components are those of `grid` while all components in `input` that depend on "positions" will be present in the output, modified by averaging.

If the `grid` input contains invalid positions and `missing` is not set, the grid's invalid positions are replaced with a new invalid positions component computed. If `missing` is set, then the invalid positions component from the `grid` input is kept and is in the output.

Example Visual Program

    SIMPLE/Regrid.net

See Also

Connect, Construct, Include, AutoGrid

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