If I remember my JSON correctly, it looks like your JSON output represents an array of generic objects with 3 properties: coor, x, and y.
Also, I'm not sure what the format of your input string is but it looks like you are using two pipe chars (||) as a delimiter.
This might be helpful:
$input_str = "1447615481,0,0||1052646429,0,0";
$coords = explode('||', $input_str);
$result_arr = array();
foreach($coords as $coord) {
$coord_arr = explode(',', $coord);
$coord_obj = (object)$coord_arr; // use variable casting to cast the array as a stdClass object
$result_arr[] = $coord_obj;
}
$output_string = json_encode($result_arr); // use the json_encode function to create JSON out of your $result_arr
