here API... "distance"... is it meters? Is it miles? Feet?
Using the API here.com I am able to get lots of great info, one item is the distance somewhere is from the supplied location in their search api. The documentation shows the distance as a text example output, but I can't find anywhere that explains what the unit of measurement is. Maybe all sites use meters and this is just a dumb question? Maybe I am just not that good at searching through the documentation and it wasn't as hard to find as it seems? Maybe you have worked with the Here API and just know the answer?
Any help would be appreciated!
-dan
As mentioned in their documents, they use meters
information about each route segment (interconnection) in between two consecutive waypoints including the distance between them in meters and the estimated time in seconds
check it out here press ( cmd + F for mac or ctrl + F for windows ) and paste the above sentence you should be able to see it.
UPDATE: Check also here they mention its meters
It is meters. Please use our documentation page to get information on all the request and response fields for any API - developer.here.com/documentation/versions
Related
I've been researching CLDR and IANA in order to find a centralized mapping of UN/LOCODEs to Olsen Timezones.
Ideally I would like to have for example:
+--------------+--------------------+
|un_locode |timezone |
+--------------+--------------------+
|USLAX | America/Los_Angeles|
+--------------+--------------------+
for every UN/LOCODE.
Are my nube skills failing me in understanding how to use these sources to reach my goal? (If so please help point me towards the scripting that would allow me to automate providing these mappings).
Or, do these sources fail to have the data correlation that I'm looking for? (If so please let me know if you have a reliable source).
We faced the exact same problem and hence had to provide a solution.
This solution involves linking the UN/LOCODES database with a geolocation/timezone database.
There are a few caveats to this approach that were captured by Matt Johnson's answer and the accompanying comments.
Namely:
the UN/LOCODE database of coordinates is not complete[1] and sometime has inaccurate data[2]
in some cases, a 1 to 1 mapping between the UN/LOCODE and a timezone is impossible due to the political nature of the timezones.
the two points above are worsened by the inaccuracy of free coordinates-to-timezone databases. It is helpful to get a dataset that also includes territorial waters so that ports timezones can be properly linked to the country they belong.
The following repository https://github.com/Portchain/un_locodes_sql contains the code to extract and link the data. It outputs a SQL file that can be imported into a PostgreSQL DB.
The geolocation/timezone data is based on the geo-tz[3] module which seems to source its data from timezone-boundary-builder[4].
Again, the list provided by our repository is of course incomplete and inaccurate. If you see any error in the data, please open a github issue and let's make an accurate, open source list of UN/LOCODE, coordinates and timezone information.
[1] For example, both Los Angeles and San Francisco, USA (USLAX & USSFO) are missing coordinates in the UN/LOCODE database.
[2] The petroleum port of Abu al Bukhoosh (AEABU) is situated in Abu Dhabi (UAE). Its coordinates in the UN/LOCODE database position the port right in the middle of the Persian Gulf (https://www.port-directory.com/ports/abu_al_bukhoosh/). When resolved, this causes the timezone to be unknown.
[3] https://github.com/evansiroky/node-geo-tz
[4] https://github.com/evansiroky/timezone-boundary-builder
The GeoNames free database of cities (which is available to download) provides: city names, latitude/longitude and, most importantly, timezone information. You can fairly quickly make your own database connecting this information with the UN/LOCODE code lists based on the name/country/coordinates.
I've not seen such a source. You could try to create one by mapping the lat/lon coordinates for those entries that have them, and correlating to IANA time zone by one of the methods listed here.
However, be sure to read Wikipedia's article about UN/LOCODE, especially describing errors with coordinates. Also note that many of the coordinates simply not in the data - why? I don't know.
The list of UN/LOCODE for the US is here, and show Los Angeles to be US LAX (not UNLAX). Its coordinates field is blank.
If you can find some other reliable source of UN/LOCODE to lat/lon, then you are in business. A quick search found that GeoNames claims to have this in their premium data subscription, but I haven't investigated further.
CLDR's map is here: https://unicode.org/reports/tr35/#Time_Zone_Identifiers
I saw CLDR tagged but not mentioned.
I am developing a location-based application in which I need to get nearby location name of any geopoint selected by user. I'm using Google Places API which is working fine for me.
Only problem is the service returns null for geopoints in water. Is there any way that I can retrieve nearby locations for a geopoint in water or ocean?
AFAIK the API has no way to do that.
So, you've got two options, in order of the effort it takes:
When user taps water just throw a dialog saying "Please select a
point on land". Next to no effort and will slightly annoy the user.
Try to find the closest land geopoint yourself and use it to run the API request on
(instead of the original point). Below are some ideas on that.
A good approach can be based on this answer: basically you can get a KML file with land polygons. For performance reasons, you can simplify the polygons to the extent that makes sense for your zoom levels. Now if your point is in one of those polygons -- it's sea. And you can simply iterate over all polygon edges and pick the one that's closest to your point, then pick a point on it - again closest to your point - and do one little epsilon-sized step towards the outside of the polygon to get a land point you can do a geocode request on. Also, the original author suggests you can use Haversine formula to determine neares land point -- I'm not really familiar with the appliance of that one.
The downside is, you have to deal with KML, iterate over a lot of polygons and optimize them (and lose precision doing that, in addition to possible differences between marineregions.org data and Google Places data)
Another cool trick you could try is using Sobel Filter [edge detection] on the visible map fragment to determine where coastline is (although you will get some false positives there), then trace it (as in raster->vector) to get some points and edges to calculate the closest land position with, in a manner similar to the former approach. Here's a clumsy drawing of the idea
For Sobel edge detection, consider GPUImage lib -- they have the filter implemented and it's probably going to work crazy fast since the lib does all the calculations on GPU.
UPD Turns out there's also a service called Koordinates that has coastline data available, check the answer here
I have tried a lot and googled a lot but finally I'm ending up by putting this query here.
I have user's long and lat, now I want to get all the nearby localities of specific range i.e 500 Kilometres. I searched and came to know google places API can help me out in this, but It is not bringing correct result.
https://maps.googleapis.com/maps/api/place/search/json?location=33.7167,73.0667&radius=500&type=funeral_home&sensor=false&key=key
In above mentioned link I have given a type "funeral_home" respectively but the result it brings is not of type funeral_home. It is bringing data from every type irrespective of the type i provide. Anyone please help and thanks in advance.
The parameters name is types (not type). Changing that returns zero results (no errors).
The radius parameter is actually measured in meters (not km), with a max of 50,000. Changing that too gives 5 results (no errors).
I'd like to calculate the closest country (as viewed on a world map) in a given direction (provided in degrees) from a user's current location.
I realize one way of doing this is to use the formula provided here to step in, for example, 5-mile increments from point to point until I finally reach a country that is not the user's starting country. However, that seems horribly inefficient with regard to use of geocoding resources.
Do any of you know of a better algorithm I could use for this?
Thanks in advance.
One way to reduce the amount of reverse geocoding operations is to treat this problem as a search for the border. If you use a binary search algorithm, and reverse geocode each point, you find where the country changes from your current country to the adjacent country with a minimum number of reverse geocode operations.
In the binary search, your heading is constant, and you have a minimum range (5 miles) and a maximum range (12,000 miles), you are searching for the range at which the border lies. Then you reverse geocode a position just beyond the border to find out what country is there. One problem is that just beyond the border might be ocean.
I would use MKReverseGeocoding. Check this SO question for code examples.
my Application is given a list of Geocorrdinates and now I have to determine which of those Coordinates are inside a defined Area. For example the Search would definiton would be: Show me all Areas where 100 Coordinates are in an Area of 1km^2. So I have to find out which of these coordinates are together in Areas of 1km^2 and more than 100.
But that seems to be a hard Job for my understanding of geocoordinates and I hope someone can help me with that.
The Latitude coordinates are consistent and Distance between two degrees is 111km. For example the Distance between N50,985° and N50,995° is 1,11km. The Distance between 2 Longtitude Coordinates is not so easy and depends on the Latitude coordinate.
But to be honest, I really don't know how to start.
Does someone have an Idea and can help me?
Thank you
twickl
what you need is a geospatial database, I'd recommend PostgreSQL with PostGIS. It provides the function you need to calculate this kind of stuff. Also search for good tutorials about it. An example is a radius search like "give me all McDonalds in a radius of 10km where I live"
If the problem with having a database is simply that you don't want to host it (or pay for someone to host it) then I recommend Fusion Tables.
I don't know if it supports exactly the functionality you are looking for, however I suppose you could select a random point and do a count of everything within range of that point.
I think that what you are talking could be quite a cpu intensive task (depending on how accurate you want it to be). Not something I would personally try and unload onto a portable device.