ITT ENVI .hdr Raw Raster Reader/Writer

Licensing options for this format begin with FME Desktop 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/
Optional

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
value

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.

About FME Rasters Tiling and Mosaicking
Raster Properties Band Combining and Separating
Band Properties Band and Palette Selection
Palette Properties Raster Processing
Compression Raster versus Vector Features
Pyramiding Raster File Naming
Interleaving World Files
Interpretation and Data Type TAB Files
Palette Resolution  

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.