Is there any way to get the approximate length and width of a building, given its' address from an API such as google maps or similar? I basically want to use it to find the lat, long coordinates of the approximate boundaries of any building or area that the address is inputted for. Free APIs or services would be preferred.
I don't think so - that would require enormous efort to catalogize most of the map into "is a building/is not a building" (I'd guess the military might have that, but they're unlikely to share (if they even have it)). What you could do is this:
- geocode address to lat/long
- grab satellite image of the surroundings
- try to detect shape in that
- estimate physical size from zoom+pixel size
I see a few problems there:
not sure if GMaps allows image scraping
the building may not be distinguishable from the background
the address might be geocoded off a building, or betwen two buildings
the address might be shared amongst multiple buildings
Related
A tile sent from Nokia Here-Map tiles API, contains at least two POIs that do not exists in real life and also not on other Map services like Google Maps and OpenStreetMap. How can i get accurate/fresh POIs with the Map Tiles Api?
I'm using the service with LeafletJs, and i use a hybrid.day base map and a base one, with the pois parameter set to true and map version set to "newest". The tiles i'm getting effectively contains POIs but it doesn't seem accurate. I wrote to the sales support at Nokia Here, i'm not sure they can help me, but the website also indicate to use stackoverflow for technical questions. Mine doesn't seem like a sales related question or a technical one but i see no other alternative contact.
This is a link to get a tile with incorrect POIs:
https://4.base.maps.cit.api.here.com/maptile/2.1/maptile/bd9e007617/normal.day/17/59178/60113/256/png8?app_id=mVrBstuYsfUVga31l6IX&app_code=xphvU-Uj071dI-UkNaxMrg&lg=fre&pois=true&style=default
The tile contains two POIs that do not exists in real life or on other map services like OpenStreetMap. The two are: "Ecobank" and "Restorant Aku".
The place the map shows is around these coordinates: lat:14.729235451930021
lng:-17.46165559897639
The returned tile shouldn't contains inexistant POIs.
This is an error in HERE database. You should report it through HERE Map Creator
It will go through some kind of quality moderation, so it may take a few weeks. Maybe adding a fresh photo would speed up things.
I am using here map api for getting nearby places but it is giving blank data (/places/v1/descover/here). While in /descover/explore/ it is giving so many records on same lat long. I am sharing screenshot for better understanding, Visit https://www.awesomescreenshot.com/image/3804672/65583a3e4f228ade754feba101ef26eb.
This depends on the use case you have.
The Here entrypoint helps users to identify direct places at their location or at a point selected on a map by returning places close to a given point, sorted by distance. (Normally the closest known places are returned, but if the uncertainty in the position is high then some nearer places are excluded from the result in favour of more popular places in the area of uncertainty.)
Then again the Explore entrypoint retrieves a complete list of relevant places nearby a given position or area. It answers the question "What interesting places are in the viewport of the map?" The results presented to the user are confined to those located in the current map view or search area and are ordered by popularity.
In general I would recommend to use the Explore entrypoint as the Here one is deprecated:
https://developer.here.com/documentation/places/topics_api/entrypoint-maturity-availability.html
I am trying to get the distance traveled on a transit route -- particularly San Francisco MUNI, but the standards NextBus, GTFS, and Google Maps API appear to be universal. I'm comfortable using any of these APIs, I'm just not sure how to go about this problem.
The easy way - ask Google Maps (this using webservices, but there is also the javascript API):
http://maps.googleapis.com/maps/api/directions/json?origin=37.7954199,-122.397&destination=37.7873299,-122.44691&sensor=false&mode=transit&departure_time=1348109609&alternatives=true
this JSON includes distance traveled, but there are two issues:
Google does not allow you to use this data unless you're displaying a map, which I don't want to do
I would need to ensure that the distance returned is for the correct route/line, since it can/will give multiple routing options. This is probably doable but would require more logic.
EDIT: using alternatives=true (or provideRouteAlternatives: true using the javascript API) only returns a maximum of 3 routes, which here in SF often doesn't include the route I'm looking for (other transit agencies, multiple lines on the same route, etc). So this isn't such a great option.
NextBus:
example route config:
http://webservices.nextbus.com/service/publicXMLFeed?command=routeConfig&a=sf-muni&r=1
The coordinates for each stop are given, but connecting the dots on those is not the same as the route taken -- it will cut corners, etc, and I need this to be accurate. The actual route taken is given under <path>/<point>, but I don't see any obvious correlation between stop and path coordinates. Plus, NextBus says in their documentation (p.10 near the bottom) that you should NOT connect points between <path> segments, they're only meant for drawing on a map and can overlap.
GTFS:
The GTFS data also separates stop and "shape" coordinates (like NextBus paths). Unfortunately, the coordinates are slightly different for the same stops between NextBus and GTFS (rounding), though the stop ID/tags are the same. Also, the data files are in the megabytes, and I need to use this for a mobile app. I suppose I could put all the data in a database and query that, but that still leaves figuring out how to correlate the stops with the shape. The "shapes_distance_traveled" column in the shapes.txt file is especially promising. MUNI chooses to leave the optional "shapes_distance_traveled" field out of stop_times.txt, though.
Any advice would be appreciated, I understand this seems like an epic task to get a simple value. Maybe I'll just throw a map in to legitimately use the distance :)
Instead of using Google Maps, I would look into the un-encumbered licensing of OpenStreetMap. There are multiple
routing engines that can use OSM data. Personally, I would use routing in PostGIS or SQLite, but depending on your skillset you might choose another.
You've clearly done your research, (+1), and as you said, the easy way is to ask Google. If it is worth for you then you might want to look into purchasing a business licence to use the Google Maps API, and negotiate with them about the requirement of displaying a map. That's the only legal way I can think of with the Google API. Alternatively, you can try building you own routing engine with data from the TIGER data set, which is freely available from the US Census Bureau, but again, as you said, it may seem like an epic task. :-)
So what I'm trying to do is the following:
Have a map (such as Google Maps or questMaps). It doesn't matter at all which API I need to use.
On that map have an overlay on the streets. So say (for example) the street has bad lightning at night, it will be colored red. If it has good lightning it will have a green overlay.
Based on the overlay the map creates a custom route (for example the user only wants to walk on the green/well lit streets).
I have no idea how to accomplish this (especially step 3).
First, you'll have to decide what data you need. How do you categorize certain streets as lit or unlit? What if some parts of a street are well lit and some have no lights? Do you need to know the location of every streetlight in your area? What if lights burn out?
After figuring out what data you need, you need to build your dataset. I'd be VERY surprised if this data already exists, so you will probably need to gather it yourself. Either go around town and take notes, or crowdsource the project, or figure out some other way.
Once you have gathered your data, learn the drawing API of whatever mapping tool you wish to use. They all should have functions in their API for drawing colored lines (for streets) or points (for streetlights) on top of an existing map.
Finally, learn the navigational API of the mapping tool you chose. You're right, this is a hard step. I know Google Maps lets you specify certain waypoints when requesting directions; maybe your app can calculate well-lit waypoints and feed them to Google Maps' Directions service to influence the route it generates.
Good luck!
For custom routing, you need to read up on "Graph Theory". This ignores the geography of the street map, and considers it as a set of junctions (nodes or vertices in the graph theory jargon) connected by edges. You can assign weights to edges - these could be lengths, travel times, ones and zeroes etc. Anything. They can have no relation to the position on the map.
So for your application, you'd assign a large weight to unlit streets, and a small weight to lit streets, then use a standard minimum-weight algorithm to get a route from one node to another.
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.