public static Position TryExtractPositionFromFile(string file)
{
Console.WriteLine(file);
IReadOnlyList <Directory> directories;
try
{
directories = ImageMetadataReader.ReadMetadata(file);
}
catch (ImageProcessingException)
{
Console.WriteLine("Unable to process {0}", file);
return(null);
}
if (!directories.Any())
{
return(null);
}
var latitude = directories.SelectMany(x => x.Tags).FirstOrDefault(t => t.Name == "GPS Latitude");
var longitude = directories.SelectMany(x => x.Tags).FirstOrDefault(t => t.Name == "GPS Longitude");
var date = directories.SelectMany(x => x.Tags).FirstOrDefault(t => t.Name == "GPS Date Stamp");
var time = directories.SelectMany(x => x.Tags).FirstOrDefault(t => t.Name == "GPS Time-Stamp");
var dilutionOfPrecision = directories.SelectMany(x => x.Tags).Where(t => t.Name.StartsWith("GPS DOP")).FirstOrDefault();
// sometimes DOP is represented as rational value (numerator, denominator), sometimes as double.
if (latitude != null && longitude != null && date != null && time != null)
{
var dateTime = $"{date.Description} {time.Description}";
Console.WriteLine(dateTime);
Console.WriteLine(gpsFormat);
var dateTimeUtc = DateTimeOffset.ParseExact(dateTime, gpsFormat, null, System.Globalization.DateTimeStyles.AssumeUniversal);
Console.WriteLine("[{0}]: {1}, {2}", dateTimeUtc, latitude.Description, longitude.Description);
return(new Position(dateTimeUtc,
LatLongParser.ParseString(latitude.Description),
LatLongParser.ParseString(longitude.Description),
dilutionOfPrecision == null ? 0.0 : ExifParser.ParseRationalOrDouble(dilutionOfPrecision.Description)));
}
if (latitude != null && longitude != null)
{
var filesystemTime = directories.SelectMany(x => x.Tags).FirstOrDefault(t => t.Name == "File Modified Date");
if (filesystemTime != null)
{
var dateTime = DateTimeOffset.ParseExact(filesystemTime.Description, fileModifiedDateFormat, CultureInfo.InvariantCulture);
Console.WriteLine("[{0}]: {1}, {2}", dateTime, latitude.Description, longitude.Description);
return(new Position(dateTime, LatLongParser.ParseString(latitude.Description), LatLongParser.ParseString(longitude.Description), PositionUnit.WGS84));
}
}
return(null);
}
public void TestParseDouble()
{
Assertions.AreApproximatelyEqual(3.946, ExifParser.ParseRationalOrDouble("3.946"));
}
