Our app used to display Google Map in UIWebView and show keyword search results near User's current location like so:
http://maps.google.com/?q=pizza&sll=36.02667514703798%2C-78.94532340586088&z=12
Which works well and returns all pizza restaurants near the given coordinates.
Now we are required to open the native Map app on iOS devices. So according to this
We changed to
http://maps.apple.com/?q=pizza&sll=36.02667514703798%2C-78.94532340586088&z=12
which opens native Map app and search for pizza, but the results are displayed on the entire US map, not at all near the specified coordinates. Like it ignores or doesn't recognize sll parameter.
What am I doing wrong? How do I show results near User's current location? My test device is iPhone 4S running iOS 6.1.3
Thanks
I'm not sure if this will fix it but according to that same page you linked to:
'The latitude and longitude points (in decimal format, comma separated, and in that order) for the map center point.'
Your example is not comma separated. Maybe worth trying that?
Related
I see the Google Barcode API and want to use QR codes. But I want to be able to detect whether it's rightside up, rotated 90-deg, 180-deg, or 270-deg, and count these as 4 different values.
I don't think this API supports orientations. Are there any that do?
I want to build this into an iOS and Android app.
If it's not using QR Codes, it could be something else, but ideally square, not like a wide barcode.
BoofCV's QR code detector gives you precise location of position patterns and alignment patterns. There's also a bounding rectangle.
https://boofcv.org/index.php?title=Example_Detect_QR_Code
I am doing a Windows Phone app that displays a map and a scaled ellipse, and everything is working well except that I cannot select a location on the map like I can in the standard MapTask app. Am I missing something? I would like the user to select a point on the map and start navigation to that point
Or is there a way to launch the MapTask app and draw the ellipse on that?
If it is Windows Phone 8 maps that you are using then I would have plenty of examples at GitHub for it: https://github.com/nokia-developer/maps-samples
Same examples for Windows phone 7 at at: http://developer.nokia.com/community/wiki/Maps_Examples_for_Windows_phone
Basically there is no automated way on getting the location, thus, if you really want to have a geocoordinate for a location uses selected, then you:
1. Need to catch the user click on the map (check the interaction examples)
2. Get the geocoordinate for the clicked pixel of the map (there is pixel to geo function implemented with maps control)
For Navigation, if you means showing a route with the map, then check the routing examples.
If you really meant navigation, then for windows phone 7 I would not have any answers, but for Windows phone 8 there is the HERE launchers documented at: http://developer.nokia.com/resources/library/Lumia/maps-and-navigation/here-launchers.html
with here launchers you could use Drive or Walk navigation.
I've got quite strange google earth plugin behaviour. I get the camera position from the plugin to create some KML with coordinates, then I store it in database. When I reload the page, then it reads the kml, inserts it inside some other string - as a result I've got a string with whole kml document inside my javascript code. Then I load it into the plugin. Usually everything works, however after loading I see two things:
The coordinates returned by the API are not the same I have in the kml I'm loading
The camera position is sometimes moved a little bit, which causes errors like: I've got a camera inside a building, and after a couple of page refreshing, the camera suddenly is outside the building.
Do you have any hints how this could be fixed?
Example:
I've created a document, and inserted this camera tag inside:
<Camera>
<gx:ViewerOptions><gx:option name='streetview'></gx:option></gx:ViewerOptions>
<longitude>2.1201209999999993</longitude>
<latitude>48.80452499999986</latitude>
<altitude>2.4999999991174264</altitude>
<heading>22.795249807940547</heading>
<tilt>82.25987544961218</tilt>
<altitudeMode>relativeToGround</altitudeMode>
</Camera>
Then I loaded it into the plugin, and asked to fly there. When it stopeed flying, I got the coordinates using copyAsCamera() and the latitude was changed to 48.8044078508718.
The difference is not huge, just 0.000117149 but as a result it is showing a totally different place (a different room in the palace.
I'm trying to get exactly the same place, as written in the coordinates.
I have rewritten the answer to cover the various points you have made and the example you have provided.
street view
The KML data is setting <gx:ViewerOptions> to enter street view mode based on the camera. The key words being based on - a street view is an approximation. Things like the camera tilt and heading are no longer applicable as they are replaced by a SteeetView POV object. Further to that you can't guarantee that a camera at any given latitude and longitude will actually enter street view at the same given latitude and longitude.
relativeToGround and terrain data
Using altitude mode relativeToGround can cause the issue you are seeing. This is because the terrain data hasn't always finished streaming when the relatively positioned element (in your case a camera) is added.
To be clear you should use <altitudeMode>absolute</altitudeMode> and ge.ALTITUDE_ABSOLUTE.
The example you provided uses both <altitudeMode>relativeToGround</altitudeMode> and ge.ALTITUDE_RELATIVE_TO_GROUND.
You could also try disabling the terrain data by turning off the terrain layer, i.e.
ge.getLayerRoot().enableLayerById(ge.LAYER_TERRAIN, false);
multiple viewchangeend events
The viewchangeend event may fire in the middle of a viewchange, especially if the plugin pauses for a brief period during the change. Your markup is triggering street view mode which causes this to happen.
You can resolve this by using setTimeout to throttle the viewchangeend event like so.
var timer = null;
google.earth.addEventListener(ge.getView(), 'viewchangeend', function(){
if(timer){
clearTimeout(timer);
}
timer = setTimeout(eventHandler, 100);
}
);
see: https://developers.google.com/earth/documentation/events#event_listeners
Tilt discrepancy
The plugin automatically "swoops" at ground level so that it moves from looking straight down (0 degrees tilt) to straight along the horizon (90 degrees tilt). This is what is causing the discrepancy in the tilt value in the view. You are viewing objects at ground level and so the view is being automatically set - this can't be disabled.
Storing and outputting KML data
Take a look through this document, it gives some really good information of storing coordinate data and covers points like the one I mentioned - A Database Driven Earth App.
.
here goes a simple question:
I've got a showKmz() function which receives an URL belonging to a KML/KMZ file and which goes straight ward to a fetchkml() method, after that it gets appended to my Google Earth instance.
Now I want to recover the coordinates of this fetched KML/KMZ file and use them to immediatelly after load a custom ico I want to put exactly on the same location of the KML/KMZ file I fetched.
The reason for that is that I want to show this files on Google Earth with their clicable icon despite of whatever icon those KML/KMZ could have by default...
Does anybody knows a way to either achieve the goal of retrieving the coordinates or even better: a more direct way to make this custom icon superposing I want?
Thanks in advance!!
Bye!!
From here
http://code.google.com/apis/earth/documentation/kml.html
When getting a KML/Z file with fetchKml, you have in the callback an option to interact with the KMLFeatures you've obtained before appending them to the globe. There could be several items in that file which have coordinates, as well as several icons. So it sounds like you want to get the features, iterate over them, and insert an IconStyle for each (or replace existing IconStyle) to have it render with the Icon you want. You don't have to place a new feature at the same location as the existing ones.
I am looking for advice for an application I am developing that uses Google Map.
Summary:
A user has a list of criteria for searching a street segment that fulfills the criteria. The street segments will be colored with 3 colors for showing those below average, average and over average. Then the user clicks on the street segment to see an information window showing the properties of that specific segment hiding those not selected until he/she closes the window and other polyline becomes visible again. This looks quite like the Monopoly City Streets game Hasbro made some month ago the difference being I do not use Flash, I can’t use Open Street Map because it doesn’t list street segment (if it does the IDs won’t be the same anyway) and I do not have to show Google sketch building over.
Information:
I have a database of street segments with IDs, polyline points and centroid.
The database has 6,000,000 street segment records in it. To narrow the generated data a bit we focus on city. The largest city we must show has 250,000 street segments. This means 250,000 line segment polyline to show.
Our longest polyline uses 9600 characters which is stored in two 8000 varchar columns in SQL Server 2008.
We need to use the API v3 because it is faster than the API v2 and the application will be ported to iPhone. For now it's an ASP.NET 3.5 with SQl Server 2008 application.
Performance is a priority.
Problems:
Most of the demo projects that do this are made with API v2. So besides tutorial on the Google API v3 reference page I have nothing to compare performance or technology use to achieve my goal.
There is no available .NET wrapper for the API v3 yet.
Generating a 250,000 line segment polyline creates a heavy file which takes time to transfer and parse. (I have found a demo of one polyline of 390,000 points. I think the encoder would be far less efficient with more polylines with less points since there will be less rounding.)
Since streets segments are shown based on criteria, polylines must be dynamically created and cache can't be used.
Some thoughts:
KML/KMZ:
Pros:
Since it is a standard we can easily load Bing maps, Yahoo! maps, Google maps, Google Earth, with the same KML file. The data generation would be the same.
Cons:
LineString in KML cannot be encoded polyline like the Google map API can handle. So it would probably be bigger and slower to display. Zipping the file at the size it will take more processing time and require the client side to uncompress the data and I am not quite sure with 250,000 data how an iPhone would handle this and how a server would handle 40 users browsing at the same time.
JavaScript file:
Pros:
JavaScript file can have encoded polyline and would significantly reduce the file to transfer.
Cons:
Have to create my own stripped version of API v3 to add overlays, create polyline, etc. It is more complex than just create a KML file and point to the source.
GeoRSS:
This option isn't adapted for my needs I think, but I could be wrong.
MapServer:
I saw some post suggesting using MapServer to generate overlays. Not quite sure for the connection with our database and the performance it would give. Plus it requires a plugin for generating KML. It seems to me that it wouldn't allow me to do better than creating my own KML or JavaScript file. Maintenance would be simpler without.
Monopoly City Streets:
The game is now over, but for those who know what I am talking about Monopoly City Streets was showing at max zoom level only the streets that the centroid was inside the Bounds of the window. Moving the map was sending request to the server for the new streets to show. While I think this was ingenious, I have no idea how to implement something similar. The only thing I thought about was to compare if the long was inside the bound of map area X and same with Y. While this could improve performance significantly at high zoom level, this would give nothing when showing a whole city.
Clustering:
While cluster is awesome for marker, it seems we cannot cluster polylines. I would have liked something like MarkerClusterer for polylines and be able to cluster by my 3 polyline colors. This will probably stay as a “would have been freaking awesome but forget it”.
Arrow:
I will have in a future version to show a direction for the polyline and will have to show an arrow at the centroid. Loading an image or marker will only double my data so creating a custom overlay will probably be my only option. I have found that demo for something similar I would like to achieve. Unfortunately, the demo is very slow, but I only wish to show 1 arrow per polyline and not multiple like the demo. This functionality will depend on the format of data since I don't think KML support custom overlays.
Criteria:
While the application is done with ASP.NET 3.5, the port to the iPhone won't use the web to show the application and be limited in screen size for selecting the criteria. This is why I was more orienting on a service or page generating the file based on criteria passed in parameters. The service would than generate the file I need to display the polylines on the map. I could also create an aspx page that does this. The aspx page is more documented than the service way. There should be a reason.
Questions:
Should I create a web service to returns the street segments file or create an aspx page that return the file?
Should I create a JavaScript file with encoded polyline or a KML with longitude/latitude based on the fact that maximum longitude/latitude polyline have 9600 characters and I have to render maximum 250,000 line segment polyline. Or should I go with a MapServer that generate the overlay?
Will I be able to display simple arrow on the polyline on the next version.
In case of KML generation is it faster to create the file with XDocument, XmlDocument, XmlWriter and this manually or just serialize the street segment in the stream?
This is more a brainstorming Stack Overflow question than an actual code problem. Any answer helping narrow the possibilities is as good as someone having all the knowledge to point me out a better choice.
Large numbers of short GPolylines run massively slower than small numbers of long GPolylines.
The speed difference between Google Maps v2 and Google Maps v3 is not going to be significant, because most of the CPU time will be taken up by the actual graphics system of the browser. Google Maps uses the VML, SVG or Canvas graphics systems, depending on the browser. Of these, VML is by far the slowest, and that gets used whenever the browser is MSIE.
Before embarking on tackling 250,000 line segments, I suggest you take a look at this quick speed test of 200 random polylines. Try zooming and paning that map in MSIE.
Then, also consider the amount of data that needs to be sent from the server to the client to specify 250,000 line segments. The amount of data will vary depending on whether you choose KML or JSON or GeoRSS, but if you end up with 20 bytes per line segment that would take 50 seconds to fetch on a 1 megabit broadband connection. Consider whether your users would be prepared to sit around for 50 seconds.
The only solution that really makes sense is to do what Google do for their traffic overlay, and draw the lines onto tiles in the server, and have those tiles be displayed as a GTileLayerOverlay in the client.
What you need is a spatially aware database, and a server-side graphics library like gd or ImageMagik. The client asks for a tile from the server. If the zoom is above a certain level the server scans the database for line segments that have bounding boxes that overlap the bounding box of the requested tile and use the graphics library to draw them.
The zoom level limit is there to limit the amount of work that your database and server needs to do. You don't want to end up drawing 250,000 line segments onto a single zoomed out tile because that's an awful lot of hard work for the server, and isn't going to mean very much to the user.
Regarding click handling:
The easy thing to do is to listen for clicks on the map, rather than on the objects, and send the click details to a server. The server then uses the click location to search the spatially aware database and returns the details of the clicked object if there is one. The client code does this:
GEvent.addListener(map,"click",function(overlay,point) {
var url="clickserver.php?lat=" + point.lat() + "&lng=" +point.lng();
GDownloadUrl(url, function(html) {
if (html.length) {
map.openInfoWindow(html)
}
});
});
The harder thing to do is to handle the changing of the cursor when the pointer is over the polylines. There's a known technique for doing cursor changes for small markers, which works like this:
Whenever a tile is fetched, the .getTileUrl() also makes a call to a server that returns a list of hotspot boxes for that tile. As the mouse moves, the client constantly calculates which tile the mouse is over, and then scans the corresponding list of hotspot boxes.
Google themselves, in their GLayer() code, add the sophistication of performing a quadtree search to speed up the search for hotspots within a tile, but other people who have implemented this strategy in their own code reckon that's not necessary, and a linear scan of the hotspot list is fast enough.
I've no idea how to extend that to handling cursor over polyline detection.