2DGridAccumulator
Replaces the input features with a grid of two-dimensional point or polygon features having the spacing specified covering (at least) the bounding box area of all the features which enter the transformer.
Input Ports
This transformer accepts any feature.
Output Ports
The grid of point or polygon features covering the bounding box area of the input features.
Features with non-numeric attributes for Column Width and Row Height or Number of Horizontal Tiles and Number of Vertical Tiles are output through this port. However, once a feature with numeric values in these attributes is received, all following features will use these same attribute values and will not be rejected.
Rejected features will have an fme_rejection_code attribute with one of the following values: INVALID_GEOMETRY_TYPE, INVALID_PARAMETER_SURFACE_NORMAL_DEVIATION, INVALID_PARAMETER_THICKNESS.
Parameters
Transformer
The input features may be partitioned into groups based on attribute values and one bounding box feature is output for each group. If you do not specify any Group By attributes, all input features will be processed together and a single bounding box will be output.
Process At End (Blocking): This is the default behavior. Processing will only occur in this transformer once all input is present.
Process When Group Changes (Advanced): This transformer will process input groups in order. Changes of the value of the Group By parameter on the input stream will trigger processing on the currently accumulating group. This may improve overall speed (particularly with multiple, equally-sized groups), but could cause undesired behavior if input groups are not truly ordered.
There are two typical reasons for using Process When Group Changes (Advanced) . The first is incoming data that is intended to be processed in groups (and is already so ordered). In this case, the structure dictates Group By usage - not performance considerations.
The second possible reason is potential performance gains.
Performance gains are most likely when the data is already sorted (or read using a SQL ORDER BY statement) since less work is required of FME. If the data needs ordering, it can be sorted in the workspace (though the added processing overhead may negate any gains).
Sorting becomes more difficult according to the number of data streams. Multiple streams of data could be almost impossible to sort into the correct order, since all features matching a Group By value need to arrive before any features (of any feature type or dataset) belonging to the next group. In this case, using Group By with Process At End (Blocking) may be the equivalent and simpler approach.
Note: Multiple feature types and features from multiple datasets will not generally naturally occur in the correct order.
As with many scenarios, testing different approaches in your workspace with your data is the only definitive way to identify performance gains.
Grid Parameters
Specifies how the grid size will be defined. Cell Size will enable the Column Width and Row Height parameters, while Number of Cells will enable the Number of Horizontal/Vertical Tiles parameters.
Chooses a starting corner for the purposes of numbering rows and columns. Also, when Grid Type is Cell Size, the last row and/or the last column may extend beyond the bounds of the input features; here the “last” row or column is the one opposite the Starting Corner.
Choose point or polygon features.
Choosing Polygons will generate rectangular boxes with the specified column width and row height.
If Points (Corners) is selected, the corners of all the rectangles in the grid will be output. Points (Centers) will generate the middle point of each rectangle.
Note that there will be more features output for Points (Corners) than for either of Polygons and Points (Centers), since there will be one additional row and one additional column.
Cell Size
The Column Width and Row Height parameters specify in ground units the distance between output points in the grid or the width and height of the output polygons.
Important: If you use attribute values as the Column Width and/or Row Height, only the attributes of the first encountered feature of each group are used. These attributes will be ignored for any following features from the same group.
These optional parameters specify a "seed point" from which cells will be generated. Note that it is permissible to specify a value for only one of these parameters—not necessarily both.
Number of Cells
The Number of Horizontal Tiles and Number of Vertical Tiles parameters are required when the Grid Type parameter is Number of Cells, and allow you to specify how to tile the input data (for example, 5 horizontal tiles and 5 vertical tiles).
Important: If you use attribute values as the Number of Horizontal Tiles and/or Number of Vertical Tiles, only the attributes of the first encountered feature of each group are used. These attributes will be ignored for any following features from the same group.
Attributes
If Column Attribute or Row Attribute are specified, attributes will be added to each output tile that identify the position of that tile in the input raster. These indices are zero-based, beginning at the specified Starting Corner.
If Column Attribute or Row Attribute are specified, attributes will be added to each output tile that identify the position of that tile in the input raster. These indices are zero-based, beginning at the specified Starting Corner.
Editing Transformer Parameters
Using a set of menu options, transformer parameters can be assigned by referencing other elements in the workspace. More advanced functions, such as an advanced editor and an arithmetic editor, are also available in some transformers. To access a menu of these options, click beside the applicable parameter. For more information, see Transformer Parameter Menu Options.
Defining Values
There are several ways to define a value for use in a Transformer. The simplest is to simply type in a value or string, which can include functions of various types such as attribute references, math and string functions, and workspace parameters. There are a number of tools and shortcuts that can assist in constructing values, generally available from the drop-down context menu adjacent to the value field.
Using the Text Editor
The Text Editor provides a convenient way to construct text strings (including regular expressions) from various data sources, such as attributes, parameters, and constants, where the result is used directly inside a parameter.
Using the Arithmetic Editor
The Arithmetic Editor provides a convenient way to construct math expressions from various data sources, such as attributes, parameters, and feature functions, where the result is used directly inside a parameter.
Conditional Values
Set values depending on one or more test conditions that either pass or fail.
Parameter Condition Definition Dialog
Content
Expressions and strings can include a number of functions, characters, parameters, and more.
When setting values - whether entered directly in a parameter or constructed using one of the editors - strings and expressions containing String, Math, Date/Time or FME Feature Functions will have those functions evaluated. Therefore, the names of these functions (in the form @<function_name>) should not be used as literal string values.
These functions manipulate and format strings. | |
Special Characters |
A set of control characters is available in the Text Editor. |
Math functions are available in both editors. | |
Date/Time Functions | Date and time functions are available in the Text Editor. |
These operators are available in the Arithmetic Editor. | |
These return primarily feature-specific values. | |
FME and workspace-specific parameters may be used. | |
Creating and Modifying User Parameters | Create your own editable parameters. |
Dialog Options - Tables
Transformers with table-style parameters have additional tools for populating and manipulating values.
Row Reordering
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Enabled once you have clicked on a row item. Choices include:
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Cut, Copy, and Paste
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Enabled once you have clicked on a row item. Choices include:
Cut, copy, and paste may be used within a transformer, or between transformers. |
Filter
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Start typing a string, and the matrix will only display rows matching those characters. Searches all columns. This only affects the display of attributes within the transformer - it does not alter which attributes are output. |
Import
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Import populates the table with a set of new attributes read from a dataset. Specific application varies between transformers. |
Reset/Refresh
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Generally resets the table to its initial state, and may provide additional options to remove invalid entries. Behavior varies between transformers. |
Note: Not all tools are available in all transformers.
Transformer History
This transformer has been renamed from 2DGridReplacer.
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Keywords: MBR "minimum bounding rectangle" 2DGridReplacer