ImageRasterizer

The Input port takes the vector features that will be rasterized. These features are valid only if they have an fme_color attribute.

The raster drawn from a group of features.

If the Group By parameter is set to an attribute list, one raster per group will be produced.

Note: How parallel processing works with FME: see About Parallel Processing for detailed information.

This parameter determines whether or not the transformer should perform the work across parallel processes. If it is enabled, a process will be launched for each group specified by the Group By parameter.

Parallel Processing Levels

For example, on a quad-core machine, minimal parallelism will result in two simultaneous FME processes. Extreme parallelism on an 8-core machine would result in 16 simultaneous processes.

You can experiment with this feature and view the information in the Windows Task Manager and the Workbench Log window.

No: This is the default behavior. Processing will only occur in this transformer once all input is present.

By Group: This transformer will process input groups in order. Changes of the value of the Group By parameter on the input stream will trigger batch processing on the currently accumulating group. This will improve overall speed if groups are large/complex, but could cause undesired behavior if input groups are not truly ordered.

Considerations for Using Input is Ordered By

Using Ordered input can provide performance gains in some scenarios, however, it is not always preferable, or even possible. Consider the following when using it, with both one- and two-input transformers.

Single Datasets/Feature Types: Are generally the optimal candidates for Ordered processing. If you know that the dataset is correctly ordered by the Group By attribute, using Input is Ordered By can improve performance, depending on the size and complexity of the data.

If the input is coming from a database, using ORDER BY in a SQL statement to have the database pre-order the data can be an extremely effective way to improve performance. Consider using a Database Readers with a SQL statement, or the SQLCreator transformer.

Multiple Datasets/Feature Types: 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, using Ordering with multiple feature types is more complicated than processing a single feature type.

Multiple feature types and features from multiple datasets will not generally naturally occur in the correct order.

One approach is to send all features through a Sorter, sorting on the expected Group By attribute. The Sorter is a feature-holding transformer, collecting all input features, performing the sort, and then releasing them all. They can then be sent through an appropriate filter (TestFilter, AttributeFilter, GeometryFilter, or others), which are not feature-holding, and will release the features one at a time to the transformer using Input is Ordered By, now in the expected order.

The processing overhead of sorting and filtering may negate the performance gains you will get from using Input is Ordered By. In this case, using Group By without using Input is Ordered By may be the equivalent and simpler approach.

In all cases when using Input is Ordered By, if you are not sure that the incoming features are properly ordered, they should be sorted (if a single feature type), or sorted and then filtered (for more than one feature or geometry type).

As with many scenarios, testing different approaches in your workspace with your data is the only definitive way to identify performance gains.

To set the size of the output raster, specify either the dimensions or the cell size.

To set the output raster size using dimensions, set the Size Specification to RowsColumns and specify values for both the Number of Columns and Number of Rows.

To set the output raster size using cell size, set the Size Specification to CellSize and specify values for both the X Cell Spacing and Y Cell Spacing.

This parameter sets the interpretation of the output raster.

Pixel values for red, green, and blue bands will be taken from the corresponding component of a feature's fme_color attribute. Pixel values for gray bands will be the average of the fme_color components.

This parameter sets pixel values for alpha bands.

The Background Color parameter sets the background color for red, green, blue, or gray bands.

Click the colored square to the right of the text field, or edit the contents of the field directly. The color must be specified as <red>,<green>,<blue> where each of <red>, <green>, and <blue> is a number between 0 and 1.

The Background Alpha Value parameter sets the background value for any alpha bands on the raster. It must also be a number between 0 and 1.

If the Fill Background with Nodata parameter is Yes, the background color will also be flagged as the nodata value for each raster band.

If the Anti-Aliasing parameter is Yes, the output lines will be smoothed using an anti-aliasing algorithm.

The Tolerance parameter is the maximum normalized distance from a line segment or polygon vertex to a pixel to be rendered. For example a tolerance of 1.0 will draw all pixels touched by the input vector line, while a tolerance of 0.0 will draw only those pixels where the input vector line passes directly through their center. Tolerance can only be selected when anti-aliasing is off.

If the Ground Extents parameter is set to Use input data ground extents, which means the extents are not explicitly specified, the output raster extents will be determined by the union of the bounding boxes of the valid input vector features. If the Ground Extents parameter is set to Specify ground extents, the remaining Ground Extents parameters are used to specify the extents of the output raster.

Note: Note: The raster extent is absolute, measured from the outer edges of the border row and column pixels.

This specifies the minimum x value of the output raster. It is used when the Ground Extents parameter is set to Specify ground extents.

This specifies the minimum y value of the output raster. It is used when the Ground Extents parameter is set to Specify ground extents.

This specifies the maximum x value of the output raster. It is used when the Ground Extents parameter is set to Specify ground extents.

This specifies the maximum y value of the output raster. It is used when the Ground Extents parameter is set to Specify ground extents.

When drawing point clouds on color bands, the Input Component specifies which component of the point should be used to set the color of the raster pixel. If the parameter is set to Color, the points in the cloud must have a color component. If the parameter is set to Intensity, the points in the cloud must have an intensity component. The intensity component is converted to a color using a grayscale continuum, where the minimum intensity in the cloud is black and the maximum intensity in the cloud is white.