how to merge multiple url/path into multidimensional array?

$pathStrings = [
    'site\\projects\\terrace_and_balcony\\mexico.jpg',
    'site\\projects\\terrace_and_balcony\\new_york.jpg',
    'site\\projects\\terrace_and_balcony\\berlin.jpg',
    'site\\projects\\terrace_and_balcony\\Kentucky.jpg',
    'site\\projects\\terrace_and_balcony\\Utah.jpg',
    'site\\projects\\terrace_and_balcony\\Hawaii.jpg',
    'site\\projects\\private_gardens\\mexico.jpg',
    'site\\projects\\private_gardens\\new_york.jpg',
    'site\\projects\\private_gardens\\berlin.jpg',
    'site\\projects\\private_gardens\\Kentucky.jpg',
    'site\\projects\\private_gardens\\Utah.jpg',
    'site\\projects\\private_gardens\\Hawaii.jpg'
];

$paths = [];
foreach ($pathStrings as $pathString) {
    // Split by the delimiter.
    $pathParts = explode('\\', $pathString);

    // Build a nested assoc array representing the path.
    // Each key and value comes from the delimited parts of the string.
    // eg: site\projects\terrace_and_balcony\mexico.jpg
    // becomes: [
    //      'site' => [
    //              'projects' => [
    //                      'terrace_and_balcony' => [
    //                              'mexico.jpg'
    //                      ]
    //              ]
    //      ]
    // ]
    $path = [array_pop($pathParts)];
    foreach (array_reverse($pathParts) as $pathPart) {
        $path = [$pathPart => $path];
    }

    // Add it to a temp list.
    $paths[] = $path;
}

// Now, merge all the paths together recursively at once.
$tree = call_user_func_array('array_merge_recursive', $paths);

// Done.
print_r($tree);

Demo: http://sandbox.onlinephpfunctions.com/code/12c82c18625dda23682baac37b2a5a8310fb869d