134 lines
4.5 KiB
C++
134 lines
4.5 KiB
C++
#include "adsb-helpers.hpp"
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// Extracts the first ts + offset, lat, lon, alt, ias from trace entries
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std::vector<std::vector<double>> extract_trace_values(const json& data, double base_ts) {
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std::vector<std::vector<double>> result;
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if (!data.contains("trace") || !data["trace"].is_array())
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return result;
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for (const auto& entry : data["trace"]) {
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if (!entry.is_array() || entry.size() < 4)
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continue;
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std::vector<double> values;
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// Extract first four values: ts, lat, lon, alt
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for (size_t i = 0; i < 4; ++i) {
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if (entry[i].is_number()) {
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double val = entry[i].get<double>();
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if (i == 0) val += base_ts; // apply offset to first value
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values.push_back(val);
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} else if (i == 3) {
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// altitude can be null or "ground"
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if (entry[i].is_string()) {
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std::string alt_str = entry[i].get<std::string>();
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if (alt_str == "ground") {
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values.push_back(0.0);
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} else {
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values.push_back(std::numeric_limits<double>::quiet_NaN());
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}
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} else {
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values.push_back(std::numeric_limits<double>::quiet_NaN());
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}
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} else {
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values.push_back(std::numeric_limits<double>::quiet_NaN());
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}
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}
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// Extract ias if present
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if (entry.size() > 12 && entry[12].is_number()) {
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values.push_back(entry[12].get<double>());
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} else {
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values.push_back(std::numeric_limits<double>::quiet_NaN());
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}
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result.push_back(std::move(values));
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}
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return result;
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}
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// Extracts icao, r, t, timestamp into a struct
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FlightInfo extract_flight_info(const json& data) {
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FlightInfo info;
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info.icao = data.value("icao", "");
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info.r = data.value("r", "");
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info.t = data.value("t", "");
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info.timestamp = data.value("timestamp", 0.0);
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return info;
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}
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// Parse JSON from filepath
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json parse_json_file(const std::string& filepath) {
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gzFile gz_file = gzopen(filepath.c_str(), "rb");
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if (!gz_file) {
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throw std::runtime_error("Could not open gzipped file: " + filepath);
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}
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constexpr size_t BUFFER_SIZE = 4096;
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char buffer[BUFFER_SIZE];
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std::string json_str;
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int bytes_read;
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while ((bytes_read = gzread(gz_file, buffer, BUFFER_SIZE)) > 0) {
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json_str.append(buffer, bytes_read);
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}
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gzclose(gz_file);
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try {
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return json::parse(json_str);
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} catch (const std::exception& e) {
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throw std::runtime_error(std::string("JSON parse error: ") + e.what());
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}
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}
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// Write CSV file
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void write_csv(const FlightInfo& info, const std::vector<std::vector<double>>& trace_values, const std::string& output_filepath) {
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std::ofstream ofs(output_filepath);
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if (!ofs.is_open()) {
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throw std::runtime_error("Could not open output file: " + output_filepath);
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}
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// Write header
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ofs << "icao,r,t,timestamp,lat,lon,alt,ias\n";
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for (const auto& values : trace_values) {
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ofs << info.icao << "," << info.r << "," << info.t;
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for (const auto& val : values) {
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ofs << "," << std::fixed << std::setprecision(5) << val;
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}
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ofs << "\n";
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}
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ofs.close();
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}
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// Check if values are within realistic bounds
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bool check_bounds(const std::vector<double>& values) {
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if (values.size() < 4) return false;
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double lat = values[1];
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double lon = values[2];
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double alt = values[3];
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// BBOX for Norway
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// 3.076172,57.562995,31.728516,71.357067
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if (lat < 57.562995 || lat > 71.357067) return false;
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if (lon < 3.076172 || lon > 31.728516) return false;
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if (alt < 0.0) return false;
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return true;
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}
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void process_adsb_file(const std::string& input_filepath, const std::string& output_filepath) {
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json data = parse_json_file(input_filepath);
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FlightInfo info = extract_flight_info(data);
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std::vector<std::vector<double>> trace_values = extract_trace_values(data, info.timestamp);
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// Check if either start or end point is in bounds
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bool start_in_bounds = !trace_values.empty() && check_bounds(trace_values.front());
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bool end_in_bounds = !trace_values.empty() && check_bounds(trace_values.back());
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if (!start_in_bounds && !end_in_bounds) {
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return; // Skip writing if neither point is in bounds
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}
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write_csv(info, trace_values, output_filepath);
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} |