Licensing options for this format begin with FME Professional Edition.
The ENVI .hdr Raster Reader/Writer module provides FME with access to ENVI .hdr header file and the associated raw raster file.
Overview
ENVI .hdr file is a header file that stores the georeferencing information of an associated raw raster file. The georeferencing information is stored in the .hdr file with the keywords:
|
Keyword |
Value |
Required/ |
|---|---|---|
|
sample |
The number of columns of raster data in the dataset. |
Required |
|
lines |
The number of rows of raster data in the dataset. |
Required |
|
bands |
The number of bands of raster data in the dataset. |
Required |
|
interleave |
The order the pixels are arranged in the raster dataset. |
Required |
|
data type |
Data type of each pixel value in the dataset. Supported types include 8-bit unsigned integer, 16- and 32-bit signed and unsigned integer, 32- and 64-bit IEEE floating point. Unsupported types: Single and double precision complex, signed and unsigned 64-bit integer. |
Required |
| description | A description of the image or processing performed. On reading this becomes the geometry name. On writing, this is taken from the geometry name if present, or the destination filename otherwise. | Optional |
|
header offset |
The number of bytes into the file where the raster data begins. Typically 0. |
Optional |
|
byte order |
Set to 1 for data files requiring data to be byte swapped to be used on Intel/Motorola hardware. |
Optional |
|
classes |
Number of classes contained in a classification result. |
Optional |
|
class names |
Names of the classes in the classification result. This keyword is ignored if classes is not set. |
Optional |
|
class lookup |
Colormap lookup table used to map classes in a classification result to a specific color for display. This keyword is ignored if classes is not set. |
Optional |
|
band names |
Default name for each band in the dataset. |
Optional |
|
wavelength |
Wavelengths are not directly supported in the ArcGIS framework, so they are appended to the band name, or used if no band name is present. |
Optional |
|
wavelength units |
If wavelength information is also present, the wavelength units will be appended to the wavelength in the band name. |
Optional |
|
pixel size |
The cell size of pixels in this dataset. Only used if map info is not present. |
Optional |
|
map info |
Determines the coordinates of the upper left corner and the pixel size. |
Optional |
|
data ignore |
The value of NODATA in this dataset. |
Optional |
For each raster, there is only a single feature returned, since this feature will contain the entire raster.
Reader Overview
FME considers a single file to be a dataset.
Writer Overview
The ENVI .hdr writer creates and writes data into a single folder. It 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.
ENVIHDR files can only be written with square pixel dimensions.
ENVIHDR supports rasters with an arbitrary number of bands, provided all bands are the same data type and no band has a palette.