IdxMapInfo a structure with 'Map' and 'Size' describing the

relationship between the indexed elements of the

geolocation mapping

Example:

% Retrieve info about example.hdf

fileinfo = hdfinfo('example.hdf');

% Retrieve info about Scientific Data Set in example

data_set_info = fileinfo.SDS;

Please read the file hdf4copyright.txt for more information.

See also hdftool, hdfread, hdf.

Reference page in Help browser

doc hdfinfo

<hdfread> - Extract from an HDF4 file.

HDFREAD extract data from HDF file

HDFREAD reads data from a data set in an HDF or HDF-EOS file. If the

name of the data set is known, then HDFREAD searches the file for the

data. Otherwise, use HDFINFO to obtain a structure describing the

contents of the file. The fields of the structure returned by HDFINFO are

structures describing the data sets contained in the file. A structure

describing a data set may be extracted and passed directly to HDFREAD.

These options are described in detail below.

DATA = HDFREAD(FILENAME,DATASETNAME) returns in the variable DATA all

data from the file FILENAME for the data set named DATASETNAME.

DATA = HDFREAD(HINFO) returns in the variable DATA all data from the

file for the particular data set described by HINFO. HINFO is a

structure extracted from the output structure of HDFINFO.

[DATA,MAP] = HDFREAD(...) returns the image data and the colormap for an

8-bit raster image.

DATA = HDFREAD(...,PARAMETER,VALUE,PARAMETER2,VALUE2...) subsets the

data according to the string PARAMETER which specifies the type of

subsetting, and the values VALUE. The table below outlines the valid

subsetting parameters for each type of data set. Parameters marked as

"required" must be used to read data stored in that type of data set.

Parameters marked "exclusive" may not be used with any other subsetting

parameter, except any required parameters. When a parameter requires

multiple values, the values must be stored in a cell array. Note that

the number of values for a parameter may vary for the type of data set.

These differences are mentioned in the description of the parameter.

DATA = HDFREAD(FILENAME,EOSNAME,PARAMETER,VALUE,PARAMETER2,VALUE2...)

subsets the data field from the HDF-EOS point, grid, or swath specified

by EOSNAME.

Table of available subsetting parameters

Data Set | Subsetting Parameters

========================================

HDF Data |

|

SDS | 'Index'

|

Vdata | 'Fields'

| 'NumRecords'

| 'FirstRecord'

_________________|____________________

HDF-EOS Data |

|

Grid | 'Fields' (required)

| 'Index' (exclusive)

| 'Tile' (exclusive)

| 'Interpolate' (exclusive)

| 'Pixels' (exclusive)

| 'Box'

| 'Time'

| 'Vertical'

|

Swath | 'Fields' (required)

| 'Index' (exclusive)

| 'Time' (exclusive)

| 'Box'

| 'Vertical'

| 'ExtMode'

|

Point | 'Level' (required)

| 'Fields' (required)

| 'RecordNumbers'

| 'Box'

| 'Time'

There are no subsetting parameters for Raster Images

Valid parameters and their values are:

'Index'

Values for 'Index': START, STRIDE, EDGE

START, STRIDE and EDGE must be arrays the same size as the

number of dimensions. START specifies the location in the data set to

begin reading. Each number in START must be smaller than its

corresponding dimension. STRIDE is an array specifying the interval

between the values to read. EDGE is an array specifying the length of

each dimension to read. The region specified by START, STRIDE and EDGE

must be within the dimensions of the data set. If either START,

STRIDE, or EDGE is empty, then default values are calculated assuming:

starting at the first element of each dimension, a stride of one, and

EDGE to read the from the starting point to the end of the dimension.

The defaults are all ones for START and STRIDE, and EDGE is an array

containing the lengths of the corresponding dimensions. START,STRIDE

and EDGE are one based. START,STRIDE and EDGE vectors must be stored

in a cell as in the following notation: {START,STRIDE,EDGE}.

'Fields'

Values for 'Fields' are: FIELDS

Read data from the field(s) FIELDS of the data set. FIELDS can be a

single string or a cell array of strings. For Grid and Swath data sets,

only one field may be specified.

'Box'

Values for 'Box' are: LONG, LAT, MODE

LONG and LAT are numbers specifying a latitude/longitude region. MODE

defines the criterion for the inclusion of a cross track in a region.

The cross track in within a region if its midpoint is within the box,

either endpoint is within the box or any point is within the box.

Therefore MODE can have values of: 'midpoint', 'endpoint', or

'anypoint'. MODE is only valid for Swath data sets and will be ignored

if specified for Grid or Point data sets.

'Time'

Values for 'Time' are: STARTTIME, STOPTIME, MODE

STARTTIME and STOPTIME are numbers specifying a region of time. MODE

defines the criterion for the inclusion of a cross track in a region.

The cross track in within a region if its midpoint is within the box,

either endpoint is within the box or any point is within the box.

Therefore MODE can have values of: 'midpoint', 'endpoint', or

'anypoint'. MODE is only valid for Swath data sets and will be ignored

if specified for Grid or Point data sets.

'Vertical'

Values for 'Vertical' are: DIMENSION, RANGE

RANGE is a vector specifying the min and max range for the

subset. DIMENSION is the name of the field or dimension to subset by. If

DIMENSION is the dimension, then the RANGE specifies the range of

elements to extract (1 based). If DIMENSION is the field, then RANGE

specifies the range of values to extract. Vertical subsetting may be

used in conjunction with 'Box' and/or 'Time'. To subset a region along

multiple dimensions, vertical subsetting may be used up to 8 times in

one call to HDFREAD.

'ExtMode'

Values for 'ExtMode' are: EXTMODE

EXTMODE is either 'Internal' (default) or 'External'. If the mode is

set to 'Internal then the geolocation fields and data fields must be

in the same swath. If the mode is set to 'External' then the

geolocation fields and data fields may be in different swaths. This

parameter is only used for Swath data when extracting a time period or

a region.

'Pixels'

Values for 'Pixels' are: LON, LAT

LON and LAT are numbers specifying a latitude/longitude region. The

longitude/latitude region will be converted into pixel rows and

columns with the origin in the upper left-hand corner of the grid.

This is the pixel equivalent of reading a 'Box' region.

'RecordNumbers'

Available parameter for 'RecordNumbers' is: RecNums

RecNums is a vector specifying the record numbers to read.

'Level'

Value for 'Level' is: LVL

LVL is a string representing the name of the level to read or a one

based number specifying the index of the level to read or from an

HDF-EOS Point data set.

'NumRecords'

Available parameter for 'NumRecords' is: NumRecs

NumRecs is a number specifying the total number of records to read.

'FirstRecord'

Required value for 'FirstRecord' is: FirstRecord

FirstRecord is a one based number specifying the first record from which

to begin reading.

'Tile'

Required value for 'Tile' is: TileCoords

TileCoords is a vector specifying the tile coordinates to read. The

elements of TileCoords are one based numbers.

'Interpolate'