Question

I have file with binary data. This is specification:

The SRTM data files have names like “N34W119.hgt”. What do the
letters and numbers refer to, and what is “.hgt” format?

Each data file covers a one-degree-of-latitude by one-degree-of-longitude block of Earth’s surface. The first seven
characters indicate the southwest corner of the block, with N, S, E,
and W referring to north, south, east, and west. Thus, the
“N34W119.hgt” file covers latitudes 34 to 35 North and longitudes
118-119 West (this file includes downtown Los Angeles, California).
The filename extension “.hgt” simply stands for the word “height”,
meaning elevation. It is NOT a format type. These files are in “raw”
format (no headers and not compressed), 16-bit signed integers,
elevation measured in meters above sea level, in a “geographic”
(latitude and longitude array) projection, with data voids indicated
by -32768. International 3-arc-second files have 1201 columns and 1201
rows of data, with a total filesize of 2,884,802 bytes ( = 1201 x 1201
x 2). United States 1-arc-second files have 3601 columns and 3601 rows
of data, with a total filesize of 25,934,402 bytes ( = 3601 x 3601 x
2). For more information read the text file “SRTM_Topo.txt” at
http://edcftp.cr.usgs.gov/pub/data/srtm/Readme.html

Anyone can help me how I can read this file in java? It is possible to read this file to array, because I need to do some operations on elements from this file?

Answer 1

I would read the entire file into a ShortBuffer (so you choose the endianess)

FileChannel fc = new FileInputStream(file).getChannel();
ByteBuffer bb = ByteBuffer.allocateDirect((int) fc.size());
while (bb.remaining() > 0) fc.read(bb);
fc.close();
bb.flip();
// choose the right endianness
ShortBuffer sb = bb.order(ByteOrder.LITTLE_ENDIAN).asShortBuffer();