So,I'm trying to create an applications, where the user sets his destination on a map - let's say from Home to work-, then (with the help of google maps)a direction line shows on the map to guide the user to his destination, or to work in our example .
What I'm trying to achieve here is that I want the app to show any coffee house that is going to be on the user's way to work,or slightly around it, but I'm not sure how to tackle this head scratcher .
Is there a way to know if a point (C) , falls within a straight line between A and b ? or falls close by factor(x) to the line between A and B ?
I created a gist which is a Swift translation of locationIndexOnEdgeOrPath function and all the other required functions present in PolyUtil.java.
The parameters you need to pass are the co-ordinates of the point you want to check and the array of points that represent the path. (Your case only includes start and end point, so just pass those two)
The other parameters needed are closed which represents whether a line should be drawn from the last point to first point in order to close the loop; geodesic which means if the earth's curvature should be taken into consideration.
Finally, toleranceEarth is the last parameter where you need to specify how close to the path is considered being on the path.
Related
For example, in the Google Map Kit for iOS I have a two points, those are start point A, and destination point B and route drawn between them. Suppose that there is some external point C. I need to know whether point C lieing(included) on the route between A and B or not.
Yes, thanks to all of you. I'have already found the solution. When you make a request like a draw route between A and B, GMapKit returns json, with the following format routes[legs[steps[...]]]. So steps[] contains each step existing in the route, it is straight line actually from one point to another. https://developers.google.com/maps/documentation/directions/intro?hl=ru#Steps. So, my solution is to compare sought point's lat and long with lat and longs of each step in the route.
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 the longitude and latitude and the name of the place I want to look for. How do I edit the Google Maps URL so that I obtain all the places (name of the places) near a set of coordinates?
I know I could do this using Google Map API, but just for a link seems a lot of trouble.
You can use the query parameter ll for your lat and long, and you can use the query parameter q for what you want to search.
http://maps.google.com/?ll=39.774769,-74.86084
Or you can
http://maps.google.com/?q=your+query
Yeah, I had the same question for a long time and I found the perfect one. Here are some parameters from it.
https://maps.google.com/?parameter=value
q=
Used to specify the search query in Google maps search.
eg :
https://maps.google.com/?q=newyork or
https://maps.google.com/?q=51.03841,-114.01679
near=
Used to specify the location instead of putting it into q. Also has
the added effect of allowing you to increase the AddressDetails
Accuracy value by being more precise. Mostly only useful if q is a
business or suchlike.
z=
Zoom level. Can be set 19 normally, but in certain cases can go up to 23.
ll=
Latitude and longitude of the map centre point. Must be in that order. Requires decimal format. Interestingly, you can use this without q, in which case it doesn’t show a marker.
sll=
Similar to ll, only this sets the lat/long of the centre point for a business search. Requires the same input criteria as ll.
t=
Sets the kind of map shown. Can be set to:
m – normal map
k – satellite
h – hybrid
p – terrain
saddr=
Sets the starting point for directions searches. You can also add text into this in brackets to bold it in the directions sidebar.
daddr=
Sets the end point for directions searches, and again will bold any text added in brackets.You can also add "+to:" which will set via points. These can be added multiple times.
via=
Allows you to insert via points in directions. Must be in CSV format. For example, via=1,5 addresses 1 and 5 will be via points without entries in the sidebar. The start point (which is set as 0), and 2, 3 and 4 will all show full addresses.
doflg=
Changes the units used to measure distance (will default to the standard unit in country of origin). Change to ptk for metric or ptm for imperial.
msa=
Does stuff with My Maps. Set to 0 show defined My Maps, b to turn the My Maps sidebar on, 1 to show the My Maps tab on its own, or 2 to go to the new My Map creator form.
reference : http://moz.com/ugc/everything-you-never-wanted-to-know-about-google-maps-parameters
additional info:
http://maps.google.com/maps?q=loc:
put in latitude and longitude after, example:
http://maps.google.com/maps?q=loc:51.03841,-114.01679
this will show pointer on map, but will suppress geocoding of the address, best for a location without an address, or for a location where google maps shows the incorrect address.
As of Jan 2018 (update: still works in May 2022) the latest URL is:
https://google.com/maps/search/*your search string* (address, landmark, city, etc. Spaces are ok)
Examples:
https://google.com/maps/search/empire state building
https://google.com/maps/search/1600 Pennsylvania Ave NW, Washington, DC 20500
You can use the new URL for Google Maps: https://www.google.com/maps/#39.774769,-74.86084,18z
equivalent to http://maps.google.com/?ll=39.774769,-74.86084.
39.774769 is the latitude and -74.86084 is longitude and 18z is 18 zoom level.
Google now has a documentation page dedicated to Maps URLs:
https://developers.google.com/maps/documentation/urls/guide
An API key is not required.
Manipulating one of the examples, I came up with this URL scheme that fits your question:
https://www.google.com/maps/search/<search term>/#<coordinates>,<zoom level>z
A valid example of this would be:
https://www.google.com/maps/search/pizza/#41.089988,-81.542901,12z
This should show you all of the pizza places around Akron, Ohio.
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.
I am a little curious about the cute little kaleidoscopic images associated with each user on this site.
How are those generated? Possibilities are:
A list of images is already there in some folder and it is chosen randomly.
The image is generated whenever a user registers.
In any case, I am more interested in what kind of algorithm is used to generate such images.
It's called an Identicon. If you entered and e-mail, it's a based on a hash of your e-mail address. If you didn't enter an e-mail, it's based on your IP address.
Jeff posted some .NET code to generate IP based Identicons.
Its usually generated from a hash of either a user name, email address or ip address.
Stackoverflow uses Gravatar to do the image generation.
As far as I know the idea came from Don Parks, who writes about the technique he uses.
IIRC, it's generated from an IP address.
"IP Hashing" I believe it's called.
I remember reading about it on a blog; he made the code available for download. I have no idea where it was from, however. :(
The images are produced by Gravatar and details of them are outlined here, however, they do not reveal how they are doing it.
I bet each tiny tile image is given a set of other tile images it looks good with. Think of a graph with the tiles as nodes. You pick a random node for the corner and fill it's adjacent spots with partners, then rotate it and apply the same pattern four times. Then pick a color.
Instead of a graph, it could also be a square matrix in which each row represents an image, each column represents an image, and cell values are weights.
I believe the images are a 4×4 grid with the upper 2×2 grid repeated 4 times clockwise, just each time rotated 90 degrees, again clockwise. Seems the two colours are chosen randomly, and each 1×1 block is chosen from a predefined set.
EDIT: obviously my answer was ad hoc. Nice to know about identicons.
Try this: http://www.docuverse.com/blog/9block?code=(32-bit integer)8&size=(16|32|64)
substituting appropriate numbers for the parenthesized items.