The ENVI Header Format
The ENVI header file contains information ENVI us to read an image data file. ENVI typically creates a header file the first time you access a data file in a format that it does not automatically recognize. You enter the required information in the Header Info dialog, which appears when the file is opened (e Creating Header Files). You can later edit the information using the Edit ENVI Header option (Editing Header Files).
二年级绘画You can also generate an ENVI header outside ENVI using a text editor. The file must start with the text string ENVI for ENVI to recognize it as a native file header. Keywords within the file indicate critical file information. You can add comments to the file by inrting a line with a micolon as the first character. ENVI ignores the lines when parsing the header file. Comments can appear anywhere within a header file, but they must be on their own line, and the micolon must be the first character of that line. Comments cannot follow a keyword/value pair.
A description of the keywords (in alphabetical order) for an ENVI header file follows. See Example ENVI Header File for an example header file.
Table 5-1: Header File Keywords
Field Description赞美秋天的诗词
band names Allows entry of specific names for each band of an image. bands The number of bands per image file.
bbl Lists the bad band multiplier values of each band in an
image, typically 0 for bad bands and 1 for good bands.
byte order The order of the bytes in integer, long integer, 64-bit integer, unsigned 64-bit integer, floating point, double precision, and complex data types. U one of the following:
•Byte order=0 (Host (Intel) in the Header Info dialog) is least significant byte first (LSF) data (DEC and
MS-DOS systems).
•Byte order=1 (Network (IEEE) in the Header Info dialog) is most significant byte first (MSF) data (all
other platforms).
class lookup This keyword pertains to classification files. It lists RGB color definitions for each respective class, and class names.
class names This keyword pertains to classification files. It lists the
classification names.
class This keyword pertains to classification files. It defines the number of class, including the unclassified.
complex function Specifies the values to calculate from a complex image and to u when displaying the image, calculating statistics for the image, or writing the image to a new file. Values include Real, Imaginary, Power, Magnitude, and Pha. The default value is Pha.
coordinate system string When you save a georeferenced file to ENVI raster format, ENVI adds a coordinate system string field to the header file. It lists the parameters ud for a geographic coordinate system or projected coordinate system. Following are some examples:
A geographic coordinate system (for example, Geographic Lat/Lon) string contains the word GEOGCS and lists the coordinate system name, datum, spheroid, prime meridian, and units:
coordinate system string =
GEOGCS["GCS_WGS_1984",
DATUM["D_WGS_1984",
SPHEROID["WGS_1984",6378137.0,298.257223563]], PRIMEM["Greenwich",0.0],
UNIT["Degree",0.0174532925199433]]
A projected coordinate system string contains the word PROJCS and lists all of the geographic coordinate system parameters, plus detailed parameters that describe the projected coordinate system:
coordinate system string =
PROJCS["WGS_1984_South_Georgia_Lambert",
二年级数学测试卷GEOGCS["GCS_WGS_1984",
DATUM["D_WGS_1984",
SPHEROID["WGS_1984",6378137.0,298.257223563]], PRIMEM["Greenwich",0.0],
教育局通知UNIT["Degree",0.0174532925199433]],
PROJECTION["Lambert_Conformal_Conic"], PARAMETER["Fal_Easting",0.0],
PARAMETER["Fal_Northing",0.0],
PARAMETER["Central_Meridian",-37.0], PARAMETER["Standard_Parallel_1",-54.0], PARAMETER["Standard_Parallel_2",-54.75], PARAMETER["Latitude_Of_Origin",-55.0], UNIT["Meter",1.0]]
coordinate system string Refer to the ITT Visual Information Solutions Tech Tips for a list of predefined geographic and projected coordinate system strings:
1. Go to /rvices/arch.asp.
小学生好词好句好段摘抄大全2. In the Enter Keyword field, type projection engine.
3. Click Submit.
4. In the arch results, open the Tech Tip titled, "ESRI Projection Engine Reference v1.0."
data gain
values Gain values for each band.
data ignore value Currently ud only in ENVI programming
(e ENVI_FILE_QUERY in the ENVI Reference Guide for more information).女生和女生怎么做
data offt
values Offt values for each band.
data type The type of data reprentation, where 1=8-bit byte;
2=16-bit signed integer; 3=32-bit signed long integer;
4=32-bit floating point; 5=64-bit double-precision floating point; 6=2x32-bit complex, real-imaginary pair of double precision; 9=2x64-bit double-precision complex,
real-imaginary pair of double precision; 12=16-bit unsigned integer; 13=32-bit unsigned long integer; 14=64-bit signed long integer; and 15=64-bit unsigned long integer.
丹参有什么功效default bands If t, indicates which band numbers to automatically load into the Available Bands List gray scale or R, G, and B fields every time the file is opened. By default, a new image is automatically loaded when a file that has default bands defined in its header is opened. If only one band number is ud, then ENVI loads a gray scale image.
default stretch Determines what type of stretch (% linear, linear range, Gaussian, equalization, square root) to u when ENVI displays the image.
dem band Path and filename of a DEM that you associate with an image.
dem file Index (starting at 1) of a lected DEM band that you associate with an image. The dem band is not written if the DEM file contains a single band, or if the first band of an image was chon. In the cas, the dem band value defaults to 0. See Editing ENVI File Headers in the ENVI Ur's Guide.
description A character string describing the image or the processing performed.
file type The ENVI-defined file type, such as a certain data format and processing result. The available file types are listed in file (e ENVI File Type File). The file type ASCII string must match an entry in the
< file verbatim, including ca.
fwhm Lists full-width-half-maximum (FWHM) values of each band in an image. Units should be the same as tho ud for wavelength and t in the wavelength units parameter.
geo points Geographic corners for non-georeferenced files. You can enter between one and four pixel locations and their corresponding latitudes and longitudes. Following is an example:
geo points = {
1.0000, 1.0000, 3
2.89380137,
-117.07201460,
1002.0000, 1.0000, 32.87364744,
-116.95855862,海狸
1.0000, 100
2.0000, 32.80628336,
-117.09960891,
1002.0000, 1002.0000, 32.78615422,
-116.98625969}
header offt The number of bytes of imbedded header information prent in the file (for example, 128 bytes for ERDAS 7.5 .lan files). ENVI skips the bytes when reading the file.
interleave Refers to whether the data are BSQ, BIP, or BIL.
lines The number of lines per image for each band.
map info Lists geographic coordinates information in the order of projection name (UTM), reference pixel x location (in file coordinates), pixel y, pixel easting, pixel northing, x pixel size, y pixel size, proj
ection zone, North or South (UTM only).
Note - In ENVI, pixel values always refer to the upper-left corner of the pixel. Map coordinates also typically refer to the upper-left corner of the pixel. However, if you entered "magic pixel" coordinates in the ENVI header, the map coordinates would refer to the x,y coordinates entered. For example, x=1.5, y=1.5 would make the map coordinates refer to the center of the pixel.
pixel size Indicates x and y pixel size in meters for non-georeferenced files.
major frame offts The number of extra bytes to skip at the beginning and ending of the major frame. See Editing ENVI File Headers in the ENVI Ur's Guide.
minor frame offts The number of extra bytes to skip at the beginning and ending of the minor frame. See Editing ENVI File Headers in the ENVI Ur's Guide.
projection info Describes ur-defined projection information. This keyword is added to the ENVI header file if a the file us a
ur-defined projection instead of a standard projection. ENVI us this information to read the file on machines that do not contain this ur-defined projection in the
map_proj\ file.
reflectance scale factor The value that, when divided into your data, would scale it from 0-1 reflectance.
rpc info Lists rational polynomial coefficient (RPC) geolocation information if your input file has this associated information. See Editing ENVI File Headers in the ENVI Ur's Guide.
samples The number of samples (pixels) per image line for each band.
nsor type Instrument types, such as Landsat TM, SPOT, RADARSAT, and so on. The available nsor types are the
< file described in ENVI Sensor File. The nsor type ASCII string defined here must match one of the entries in file verbatim, including ca.
