PRODUCTS FORMAT DESCRIPTION
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The VEGETATION products format is composed of a mixed of ASCII files and HDF or TIFF files or another file format (TBD).
ASCII files are composed of variable length lines. Each line is less or equal to 80 characters.
Valid characters within a line are ASCII 7 bits characters. Authorized ASCII characters are defined in appendice 3
Each line end with the two following characters : CR (Carriage Return - Ascii 013) and then LF (Line feed - Ascii 010).
Data lines are composed of keywords and associated values.
The keyword start at column 1 and is separated from the value zone by one or more blanks (see keywords for more details).
The associated value zone begins at the first non blanks character encountered at the right of the keyword and end at the most at column 78 (see values for more details).
For each data line, the following paragraph gives the presence/absence status for each product type :
nothing means that the data line is mandatory for this product type
NU means that the data line is never used so never present for this product type
O means that the data line is optional for this product type depending on the product characteristics.
Comment lines begin with an exclamation mark "!".
Blanks lines are also allowed.
Comment lines and blanks lines can be situated anywhere in the file.
Keywords are written in uppercase letters. Figures and underscore are valid characters, but they cannot appear at the first position.
Blanks are prohibited inside a keyword.
The length of a keyword not exceed 25 characters
A keyword occur only once in a file.
Some keywords are associated only to some products, and does not appear in the file for other products.
Values can be :
Text values in ASCII format. In file descriptions, $ represents a blank character.
Numeric values provided using their printable representation. If no sign is specified, the value is considered as positive. For angles only, the digits reserved for degrees are left filled with 0 if the value takes less digits than those required.
HDF files are coded using the HDF library described in the HDF file :
Tag DFTAG_VERSION give the following informations :
Major version number
Minor version number
Each file includes auxiliary data associated to pixel data.
Auxiliary data are included in one or more Vdata.
Each Vdata are uniquely identify by a name, a class, a field name.
The individual fields include a keyword followed by the corresponding value. The keyword is coded on a fixed length of 25characters (blanks characters are added to the keyword to fill it until 25 characters). The whole auxiliary data, including keyword and value, is coded on a fixed length of 40 characters (blanks characters are added to the value to fill it until 40 characters). The rules for values are the same than those for ASCII files. If all the fields of a vdata are not used, the whole vdata is not included in the file.
A keyword occur only once in a file.
Some fields are required for each product, others fields migth be optionnel depending on the product characteristics, and others are not used. Required fields are default. Optionnal fields are marked O. Not used fields are marked NU. The use of fields is described for each product type.
Each file may include one or more Vdata. There will be found in the file in the same order than there are described in this document.
Pixel data are coded using SD Scientific data set, using HDF release 4.1 or higher.
Each file may include one or more SD Scientific data set. They are found in the file in the same order than there are described in this document.
Each SD is uniquely identified by a name .
Be aware that for each SD, dimsize is the number of lines, dimsize is the number of pixels, and the data are stored in row-major-order. Also, note that the array begin at (1, 1).
TIFF files must be compliant with the TIFF 6.0 format.