Licensing options for this format begin with FME Desktop Professional Edition.
The reader enables FME to read a binary raw raster file with an associated ERDAS .raw header file, with or without an Esri world file. The writer enables FME to output a binary raw raster file and an associated ERDAS .raw header file, along with an Esri world file.
Overview
An ERDAS® .raw file is a header file that stores the properties of an associated raw raster file.
The georeferencing information is read from or written to an Esri world file and some properties are stored in the .raw file with the following keywords.
Keywords
|
Keyword |
Value |
|---|---|
|
IMAGINE_RAW_FILE |
This keyword must be at the very beginning of the file, on a line by itself. |
|
HEIGHT |
The number of rows in the image. Rows are parallel to the x-axis of the map coordinate system. There is no default. |
|
WIDTH |
The number of columns in the image. Columns are parallel to the y-axis of the map coordinate system. There is no default. |
|
NUM_LAYERS |
The number of spectral bands in the image. The default is 1. |
|
DATA_TYPE |
The data type used for each pixel in each band. Acceptable values are U1, U2, U4, U8, U16, U32, S16, S32, F32, and F64. The default value is U8. For a true color image with three bands (R, G, B) stored using 8 bits for each pixel in each band, DATA_TYPE equals U8 and NUM_LAYERS equals 3, for a total of 24 bits per pixel. |
|
BYTE_ORDER |
The byte order in which image pixel values are stored. The byte order is important for 16-bit images, with 2 bytes per pixel. Acceptable values are LSB, which is Intel byte order (Silicon Graphics, DEC Alpha, PC) or little-endian, and MSB, which is Motorola byte order (Sun, HP, etc.) or big-endian. Required for DATA_TYPE values of U16, S16, U32, S32, F32 and F64. It is ignored otherwise. |
|
FORMAT |
The organization of the bands in the image file. Acceptable values are BIL, which is band interleaved by line, BIP, which is band interleaved by pixel, and BSQ, which is band sequential. If not specified, default layout is BIL. |
|
PIXEL_FILES |
The name of the file in which raster data resides. Default value is the name of the raw file without an extension. The reader currently ignores this keyword and assumes the name of the raw file is the name of the header without an extension. |
|
DATA_OFFSET |
The number of bytes of data in the image file to skip in order to reach the start of the image data. This keyword allows you to bypass any existing image header information in the file. The default value is zero bytes. |
|
END_RAW_FILE |
Indicates the end of the raw file. The reader will ignore any keywords after it reads this keyword. |
For each raster, there is only a single feature returned, since this feature will contain the entire raster.
Note: The current version of ERDAS RAW Reader/Writer does not support the LAYER_SKIP_BYTES, RECORD_SKIP_BYTES, TILE_WIDTH and TILE_HEIGHT directives.
Since the reader does not read the PIXEL_FILES directive, the reader always assumes that the raw binary file is the dataset, and the name of this file is the name of the header without the extension. Currently, the reader does not support multiple raw binary files in one dataset or a single file with both the header and the raw binary data at the same time.
Reader Overview
FME considers a single binary ERDAS RAW file associated with a header file to be a dataset. The ERDAS RAW file contains pixel data, and each pixel in the file is a point in a single FME raster feature. The header file contains the raster properties.
Writer Overview
The ERDAS RAW writer creates and writes data into a single folder specified by the Dataset parameter.
The ERDAS RAW file contains pixel data: each pixel in the file is a point in a single FME raster feature. The ERDAS RAW writer distinguishes duplicate output files by appending numbers to the filenames.
FME Raster Features
FME raster features represent raster data and use several concepts that are unlike those used in the handling of vector data. The topics below describe how FME processes raster data.
ERDAS Raw supports rasters with an arbitrary number of bands, provided all bands are the same data type and no band has a palette.