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  • Trilateration using 3 latitude and longitude points, and 3 distances

    - by nohat
    There exists an unknown target location (latitude and longitude co-ordinates). I have 3 latitude and longitude co-ordinate pairs and for each pair a distance in kilometers to the target location. How can I calculate the co-ordinates of the target location? For example, say I have the following data points 37.418436,-121.963477 0.265710701754km 37.417243,-121.961889 0.234592423446km 37.418692,-121.960194 0.0548954278262km What I'd like is what would the guts of the function that takes that as input and returns 37.417959,-121.961954 as output look like? I understand how to calculate the distance between two points, from http://www.movable-type.co.uk/scripts/latlong.html I understand the general principle that with three circles you get exactly one point of overlap. What I'm hazy on is the math needed to calculate that point with this input.

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  • Reversed Latitude/Longitude US Tiger/Line Shape File to MySQL w/ OGR2OGRP

    - by Dave LeJeune
    Hi - I've downloaded the latest set (2010) of TIGER edge shape files (ESRI shapefile format) from the US Census website and am loading them into MySQL using the GDAL ogr2ogr utility. A new table (geotest) does get created with a SHAPE column that has the geometry defined as a LINESTRING. However, I am seeing reversed latitude and longitude values that get reversed when running the following command: ogr2ogr -f "MySQL" MySQL:"geo,user=lejeuned,host=localhost,password=cnickl234" -nln geotest -nlt LINESTRING -append -a_srs "EPSG:4326" -lco engine=MYISAM tl_2010_01021_edges.shp Mapping the latitude/longitude (after reversing them of course) they appear to be spot on so I suspect there is just something I am doing wrong or flag I am missing which is causing the latitude and longitudes to be transposed. When I select the SHAPE column using astext() I get the following result: LINESTRING(-86.69863 32.973164,-86.69853 32.97302,-86.69856 32.97287,-86.698613 32.972825,-86.6988 32.972825,-86.6989 32.972892,-86.6989 32.973002,-86.69874 32.97316,-86.69864 32.97318,-86.69863 32.973164) Any ideas what I am doing wrong?

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  • Get latitude and longitude using map interface

    - by Dave Jarvis
    Problem Allow website users to enter four latitude and longitude coordinates. Proposed Solution Integrate Google Maps API, and add a click event handler, similar to: http://itouchmap.com/latlong.html http://stackoverflow.com/questions/2770421/how-retrieve-latitude-and-longitude-via-google-maps-api http://marcgrabanski.com/article/jquery-google-maps-tutorial-basics The data would populate into a hidden form field. Questions What other ways (besides <input type='text' ... />) outside of Google's API are available to solve the problem? How would you restrict the number of lat/long points the user can choose? Would using those coordinates violate Google's Terms of Service? Thank you!

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  • Obtain Latitude and Longitude from a GeoTIFF File

    - by Mikee
    Using GDAL in Python, how do you get the latitude and longitude of a GeoTIFF file? GeoTIFF's do not appear to store any coordinate information. Instead, they store the XY Origin coordinates. However, the XY coordinates do not provide the latitude and longitude of the top left corner and bottom left corner. It appears I will need to do some math to solve this problem, but I don't have a clue on where to start. What procedure is required to have this performed? I know that the GetGeoTransform() method is important for this, however, I don't know what to do with it from there.

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  • Sort latitude and longitude coordinates into clockwise quadrangle

    - by Dave Jarvis
    Problem Users can provide up to four latitude and longitude coordinates, in any order. They do so with Google Maps. Using Google's Polygon API (v3), the coordinates they select should highlight the selected area between the four coordinates. Solutions and Searches http://stackoverflow.com/questions/242404/sort-four-points-in-clockwise-order Graham's scan seems too complicated for four coordinates Sort the coordinates into two arrays (one by latitude, the other longitude) ... then? Question How do you sort the coordinates in (counter-)clockwise order, using JavaScript? Code Here is what I have so far: // Ensures the markers are sorted: NW, NE, SE, SW function sortMarkers() { var ns = markers.slice( 0 ); var ew = markers.slice( 0 ); ew.sort( function( a, b ) { if( a.lat() < b.lat() ) { return -1; } else if( a.lat() > b.lat() ) { return 1; } return 0; }); ns.sort( function( a, b ) { if( a.lng() < b.lng() ) { return -1; } else if( a.lng() > b.lng() ) { return 1; } return 0; }); } What is a better approach? Thank you.

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  • Sort latitude and longitude coordinates into clockwise ordered quadrilateral

    - by Dave Jarvis
    Problem Users can provide up to four latitude and longitude coordinates, in any order. They do so with Google Maps. Using Google's Polygon API (v3), the coordinates they select should highlight the selected area between the four coordinates. Solutions and Searches http://www.geocodezip.com/map-markers_ConvexHull_Polygon.asp http://softsurfer.com/Archive/algorithm_0103/algorithm_0103.htm http://stackoverflow.com/questions/2374708/how-to-sort-points-in-a-google-maps-polygon-so-that-lines-do-not-cross http://stackoverflow.com/questions/242404/sort-four-points-in-clockwise-order http://en.literateprograms.org/Quickhull_%28Javascript%29 Graham's scan seems too complicated for four coordinates Sort the coordinates into two arrays (one by latitude, the other longitude) ... then? Jarvis March algorithm? Question How do you sort the coordinates in (counter-)clockwise order, using JavaScript? Code Here is what I have so far: // Ensures the markers are sorted: NW, NE, SE, SW function sortMarkers() { var ns = markers.slice( 0 ); var ew = markers.slice( 0 ); ew.sort( function( a, b ) { if( a.position.lat() < b.position.lat() ) { return -1; } else if( a.position.lat() > b.position.lat() ) { return 1; } return 0; }); ns.sort( function( a, b ) { if( a.position.lng() < b.position.lng() ) { return -1; } else if( a.position.lng() > b.position.lng() ) { return 1; } return 0; }); var nw; var ne; var se; var sw; if( ew.indexOf( ns[0] ) > 1 ) { nw = ns[0]; } else { ne = ns[0]; } if( ew.indexOf( ns[1] ) > 1 ) { nw = ns[1]; } else { ne = ns[1]; } if( ew.indexOf( ns[2] ) > 1 ) { sw = ns[2]; } else { se = ns[2]; } if( ew.indexOf( ns[3] ) > 1 ) { sw = ns[3]; } else { se = ns[3]; } markers[0] = nw; markers[1] = ne; markers[2] = se; markers[3] = sw; } What is a better approach? The recursive Convex Hull algorithm is overkill for four points in the data set. Thank you.

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  • Using Shapefile data to determine neighborhood for a longitude/latitude

    - by Kunal
    I'm trying to determine the neighborhood for a location, based on Zillow's freely published Shapefile data. I don't really know anything about the Shapefile format, and am having some trouble finding tutorials online -- but I basically want to take latitude/longitude pairs, and run it against the Shapefile data to determine the corresponding neighborhood(s). Can anyone point me in the right direction? Not even sure where to start. This is where I've grabbed the Shapefile files: http://www.zillow.com/howto/api/neighborhood-boundaries.htm

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  • How to implement geo-based data store and computation?

    - by Mickey Shine
    Well, let me explain this briefly: 1.I want to build a website that provides location based services, like http://fireeagle.yahoo.net/ . 2.I guess most of these services have something do with longitude and latitude. 3.Is there any particular database/datastore/data structures fit well for such apps? I mean easy to store longitude, latitude and easy to compute or easy to use. I am new to this and any feedbacks are welcome

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  • Java: Calculate distance between a large number of locations and performance

    - by Ally
    I'm creating an application that will tell a user how far away a large number of points are from their current position. Each point has a longitude and latitude. I've read over this article http://www.movable-type.co.uk/scripts/latlong.html and seen this post http://stackoverflow.com/questions/837872/calculate-distance-in-meters-when-you-know-longitude-and-latitude-in-java There are a number of calculations (50-200) that need carried about. If speed is more important than the accuracy of these calculations, which one is best?

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  • Fastest distance lookup given latitude/longitude?

    - by Ryan Detzel
    I currently have just under a million locations in a mysql database all with longitude and latitude information. With this I use another lat/lng to find the distance of certain places in the database but it's not as fast as I want it to be especially with 100+ hits a second. Is there a faster formula or possibly a faster system other than mysql for this? The formula I'm using is this. select name, ( 3959 * acos( cos( radians(42.290763) ) * cos( radians( locations.lat ) ) * cos( radians( locations.lng ) - radians(-71.35368) ) + sin( radians(42.290763) ) * sin( radians( locations.lat ) ) ) ) AS distance from locations where active = 1 HAVING distance < 10 ORDER BY distance;

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  • How to convert latitude or longitude to meters?

    - by Adam Taylor
    Hi, If I have a latitude or longitude reading in standard NMEA format is there an easy way / forumla to convert that reading to meters, which I can then implement in Java (J9)? Edit: Ok seems what I want to do is not possible /easily/, however what I really want to do is: Say I have a lat and long of a way point and a lat and long of a user is there an easy way to compare them to decide when to tell the user they are within a /reasonably/ close distance of the way point? I realise reasonable is subject but is this easily do-able or still overly maths-y? Thanks, Adam

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  • SQL 2003 Distance Latitude Longitude

    - by J.Hendrix
    I have a table full of Dealers along with their latitude and longitude. I am trying to determine the top n closest dealers to any given lat and lon. I already have the function to calculate distance between locations, but I want to do as few calculations as possible (my table can contain many thousands of entries). Currently I have to calculate the distance for each entry then sort them. Is there any way to sort before I do the calculation to improve performance? This question is good, but I will not always know my range. Should I just pick an arbitrarily high range then refine my results? I am thankful for any help the community can offer. declare @Lat real declare @lon real Set @lat = 41.05 Set @lon = -73.53 SELECT top 10 MemberID, Address1, City, State, Zip, Phone, Lat, Lon, (SELECT fun_DistanceLatLon] (@Lat,@lon,Lat,Lon)) as mDistance --Calculate distance FROM Dealers Order by (SELECT fun_DistanceLatLon] (@Lat,@lon,Lat,Lon))

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  • Distance between Long Lat coord using SQLITE

    - by munchine
    I've got an sqlite db with long and lat of shops and I want to find out the closest 5 shops. So the following code works fine. if(sqlite3_prepare_v2(db, sqlStatement, -1, &compiledStatement, NULL) == SQLITE_OK) { while (sqlite3_step(compiledStatement) == SQLITE_ROW) { NSString *branchStr = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 0)]; NSNumber *fLat = [NSNumber numberWithFloat:(float)sqlite3_column_double(compiledStatement, 1)]; NSNumber *fLong = [NSNumber numberWithFloat:(float)sqlite3_column_double(compiledStatement, 2)]; NSLog(@"Address %@, Lat = %@, Long = %@", branchStr, fLat, fLong); CLLocation *location1 = [[CLLocation alloc] initWithLatitude:currentLocation.coordinate.latitude longitude:currentLocation.coordinate.longitude]; CLLocation *location2 = [[CLLocation alloc] initWithLatitude:[fLat floatValue] longitude:[fLong floatValue]]; NSLog(@"Distance i meters: %f", [location1 getDistanceFrom:location2]); [location1 release]; [location2 release]; } } I know the distance from where I am to each shop. My question is. Is it better to put the distance back into the sqlite row, I have the row when I step thru the database. How do I do that? Do I use the UPDATE statement? Does someone have a piece of code to help me. I can read the sqlite into an array and then sort the array. Do you recommend this over the above approach? Is this more efficient? Finally, if someone has a better way to get the closest 5 shops, love to hear it.

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  • Fetch Latitude Longitude by passing postcodes to maps.google.com using Javascript

    - by Nirmal
    Hello All... I have Postcode in my large database, which contains values like SL5 9JH, LU1 3TQ etc. Now when I am pasting above postcode to maps.google.com it's pointing to a perfect location.. My requirement is like I want to pass post codes to maps.google.com and it should return a related latitude and longitude of that pointed location, that I want to store in my database. So, most probably there should be some javascript for that... If anybody have another idea regarding that please provide it.. Thanks in advance...

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  • Find all records in database that are within a certain distance of a set of lat and long points

    - by Mike L
    I've seen all the examples and here's what I got so far. my table is simple: schools (table name) - School_ID - lat - long - county - extrainfo here's my code: <?php $con = mysql_connect("xxx","xxx","xxx"); if (!$con) { die('Could not connect: ' . mysql_error()); } else {} mysql_select_db("xxx", $con); $latitude = "36.265541"; $longitude = "-119.207153"; $distance = "1"; //miles $qry = "SELECT *, (3958.75 * ACOS(SIN(" . $latitude . " / 57.2958)*SIN(lat / 57.2958)+COS(" . $latitude . " / 57.2958)*COS(lat / 57.2958)*COS(long / 57.2958 - " . $longitude . " / 57.2958))) as distance FROM schools WHERE (3958.75 * ACOS(SIN(" . $latitude . " / 57.2958)*SIN(lat / 57.2958)+COS(" . $latitude . " / 57.2958)*COS(lat / 57.2958)*COS(long / 57.2958 - " . $longitude . " / 57.2958))) <= " . $distance; $results = mysql_query($qry); if (mysql_num_rows($results) > 0) { while($row = mysql_fetch_assoc($results)) { print_r($row); } } else {} mysql_close($con); ?> but I get this error when I try to run it: Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource

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