I’ve reformatted the code that was previously mentioned here, but more importantly you have left out some of the equations mentioned in the link provided by Niklas R def LLHtoECEF(lat, lon, alt): # see http://www.mathworks.de/help/toolbox/aeroblks/llatoecefposition.html rad = np.float64(6378137.0) # Radius of the Earth (in meters) f = np.float64(1.0/298.257223563) # Flattening factor WGS84 Model cosLat = … Read more
Some numbers can be explained easily MeanRadiusEarthInKm = 6371 (according to IUGG) DegToRadDivisor = 180/PI = 57.2958 And again the zoom level doubles the size with each step, i.e. increase the zoomlevel by one halfs the size on the screen. zoom = 8 – log(factor * dist) / log(2) = 8 – log_2(factor * dist) … Read more
IS THERE ANYTHING WRONG With this query? In my opinion the WHERE clause is going to be slow because of the maths involved, and the use of functions in the WHERE clause will prevent the database using an index to speed the query – so, in effect, you will examine every restaurant in the database, … Read more
This post shows how to do this in SQL Server. And here is how to do it in MySQL: SELECT ((ACOS(SIN($lat * PI() / 180) * SIN(lat * PI() / 180) + COS($lat * PI() / 180) * COS(lat * PI() / 180) * COS(($lon – lon) * PI() / 180)) * 180 / PI()) … Read more
According to the link posted above by tomfanning, property item 0x0002 is the latitude expressed as a PropertyTagTypeRational. The rational type is defined as… Specifies that the value data member is an array of pairs of unsigned long integers. Each pair represents a fraction; the first integer is the numerator and the second integer is … Read more
Start by Comparing the distance between latitudes. Each degree of latitude is approximately 69 miles (111 kilometers) apart. The range varies (due to the earth’s slightly ellipsoid shape) from 68.703 miles (110.567 km) at the equator to 69.407 (111.699 km) at the poles. The distance between two locations will be equal or larger than the … Read more
I guess it should not be difficult to find the spherical polar coordinates from x,y,z (3d-coordinate system). r is always constant if it’s on surface. (90 – θ) your latitude (negative means it’s on the bottom) as it’s measured from top. φ is your longitude. (but not quite sure about longitude system) Also check this … Read more
Fair Warning! Before taking the advice to use the GEOGRAPHY type, make sure you are not planning on using Linq or Entity Framework to access the data because it’s not supported (as of November 2010) and you will be sad! Update Jul 2017 For those reading this answer now, it is obsolete as it refers … Read more
You can use the formula that calculates distances between two points. For example: function get_distance($latitude1, $longitude1, $latitude2, $longitude2, $unit=”Mi”) { $theta = $longitude1 – $longitude2; $distance = (sin(deg2rad($latitude1)) * sin(deg2rad($latitude2))) + (cos(deg2rad($latitude1)) * cos(deg2rad($latitude2)) * cos(deg2rad($theta))); $distance = acos($distance); $distance = rad2deg($distance); $distance = $distance * 60 * 1.1515; switch($unit) { case ‘Mi’: break; case … Read more
Edit: For (non-R) code that works for all non-polar areas on earth, see here or here. Unless you are dealing with data from a couple of exceptional areas (Svalbard and parts of Norway), this is a simple enough calculation that you might as well just do it yourself in R. Here is Wikipedia’s description of … Read more