Reading in binary file leads to empty matrix

I have a binary file ('test') together with a header file ('test.hdr') which I am trying to import into matlab. I can read out the information out of the header file, however I am struggling to read in the binary file. Here you can download the two files I am trying to import.

This is my code so far:

% read in header file
[fid message]=fopen('test.hdr','rt');
if(~isempty(message))
error(message);
return;
end

while(~feof(fid)) % Repeat the following command sequence until EOF is reached
    textline=fgetl(fid);
    [nameAndValue] = regexp(textline,'=','split');
    fieldName = strtrim(nameAndValue{1});
    value = strtrim(nameAndValue{2});
    if(~isempty(str2num(value)))
        value = str2num(value);
    else
        value = strtok(value,'''');
    end
    header.(fieldName) = value;
end
fclose(fid);

% read in binary
[fid message]=fopen('test','wb','ieee-be');
if(~isempty(message))
    error(message);
    return;
end

How could I read in the data, the header contains informatio about the data type and the dimensions of the matrix. When trying to read in data like this I get an empty matrix A.

A=fread(fid);

How could I read in this data with using the header information? The binary file is exported from ENVI and in big-endian byte order.

Answer 1

[Image Analyst]

If you are trying to open a file for reading, then why are you opening it for writing?

[fid message]=fopen('test','wb','ieee-be');

'wb' means write binary. I think you really want rb like this:

[fid message]=fopen('test','rb','ieee-be');

I also second Geoff's comment about the filename. You should use fullfile() to create a filename with the full folder, base filename, and extension. Then use exist(fullFileName, 'file') to see if it actually exists first before calling fopen().

[Walter Roberson]

Earlier you spoke of 'test' and 'test.hdr', but now you are trying to open 'topomap'

If I use your earlier code together with your later

A = fread(fid, [180,360], 'float32');

then the data looks okay when you use

imagesc(A,'XData',[180,-180], 'YData',[-90,90]); axis xy