Is there any good library that will enable to see the coarse location distribution.
I have some million data points to plot on a map. Doing it on google maps is going to be heavy. I want this to be like a dot plot.
The closest I can think to the functionality you are looking for would be to implement a heatmap layer : https://developers.google.com/maps/documentation/javascript/examples/layer-heatmap.
This would allow you to see the distribution of points without plotting them individually and thus saving you some client-side work.
How well this will work with a million+ points however I am not sure. You might be best off looking into a fusion tables combination.
Related
I'm interested in implementing some data visualizations as map layers. But I'm interested in generating data layers only above land area (land cover). A good example would be to plot population density over a coastal city. What is a good approach for this, when it comes to the data source and how to actually display layers with such detailed boundaries?
Technically, so far I'm using Leaflet.js and tiles based on OpenStreetMaps, but the question is not necessary technology specific. Also, I'm not interested in plotting this for the whole planet, but for areas of a few hundreds square kilometers (for e.g. a coastal city).
To better give an idea of what I'm interested in, this Koordinates map is something that is similar to what I'm interested in. However, I need something a bit more detailed on the borders.
Usually you need a desktop or server based GIS such coverage, but not JS to do the processing on the client side.
How you do the mapping (here: linking statistical data and land areas) depends on your data itself. You can load OSM based shape files into QGIS and do some python scripting or using the PostGIS commands to link your data and choose a map style.
Another idea would be http://geocommons.com that allow easy visualization if you upload CSV files.
Depending on your area of interest, you can obtain some highly detailed shapefiles from numerous sources. Especially if the local area provides GIS data to the public (many larger coastal cities do, e.g. New York, London). From there, you can create a GeoJSON text of the geometries (here's a free tool for that). Parsing the JSON is very simple and it's very easy to add it to leaflet maps. You can even get creative and add more keys to each geometry object with the data you want to visualize.
We are creating a speed limit map application using different colors to highlight street with different speed limits (similar to ITO speed limit map: http://www.itoworld.com/map/124?lon=-79.37151&lat=43.74796&zoom=12).
The problem we have is that we are conducting our own research and have our own speed limit data instead of pulling the data from OpenStreetMap or Google Map like ITO map. We also need to create a data storage in order to dynamically update the map as we add more speed limit information in the future.
Is there anyway to create our own instance of OpenStreetMap and replace only the speed limit information with our own data? We don't have any vector data and we have no experience working with them.
Is there any suggestion of tools to use for creating highlighting layers based on the speed limit we have? Is OpenLayers a good option?
Any help is appreciated, thank you very much.
Update 2013/11/20
Thank you very much for your answers, now we have a much better understanding of your problem. This is a university design project so we basically have no budget. We are looking for:
1) A basic "base map" that include the basic tile information (openstreetmap seems a good choice since google map api doesn't provide free road information as long as we can find)
2) A geo data server that can host our own street speed limit data (looks like geoserver and mapserver are good choices), or a design simple database that can fulfill our need(doesn't know is it possible yet)
3) A plotting tool that can render our speed limit data as "group of lines" on the map since these data will be changed frequently (openlayers and leaflet are good candidates).
Is there anything else needed?
What you want to do is a trivial programming task once you have decided a few things:
These are probably the three biggest questions you need to answer. I added some commentary, but look at each of these questions beyond this post to find what works for you.
Who do you want to use for your map? Since you only have one type of data you will want to display that data on someone else's nice looking map. The big choices are Bing, Google, OpenLayers/OSM, and ESRI. Your choice will most likely be driven by the licensing of the above services and if you are willing to pay or not. A need to support mobile devices may also factor into your decision. Since the map is what your users will see, choose the best looking map you can afford.
How will you serve up your data? You have several options to serve your speed limit data. GeoServer and MapServer and ESRI are some popular mapping software packages. If you only displaying a few layers of data all mapping software will be overkill. The actual software to render your map data will most likely affect only your pocket book, so free is good here usually.
Tiles vs Lines
You will server your data as either a group of lines sent to the browser, or as pre-rendered tiles to be loaded on top of the map. If you data changes frequently you will want to serve it dynamically as line data (an array of points.) If your data does not change frequently, you should consider tiling your data. Tiling involves pre-rending of the entire map at all zoom levels. This allows the map to be loaded very fast and this how almost all base maps are rendered. The downside is that the tile generation can take a long amount of time and tiles can take a large amount of space.
This is a very broad question. There are many components to drawing your own speed limit map.
On the front-end, there is a web browser map interface. OpenLayers is good at that. There are plenty of other tools that can do this as well, such as Leaflet or even Google Maps API.
Next is something to provide the actual speed limit route data. This can be served as a vector layer or a raster layer. There are plenty of tools here, too. UMN Mapserver is free and reasonably good. ESRI makes a whole fleet of products in this area as well.
The speed limit route data also needs to be saved somehow. This can be done in files or in a database such as PostGIS. Again, lots of great options.
It is the role of the system architect to determine which technologies to employ to solve the problem.
I'm trying to build a map with the following algorithm:
Wait for pan or zoom to occurs.
Query for all streets visible in the viewport (extent).
Color every visible street with a predefined color.
Example:
I want to show the numbers of businesses on each street, or the number of crimes committed at each street.
I have a DB which holds this kind of information (streetname, data), but each row doesn't have the location data.
Therefore, after each map zoom or pan, I cannot query all of it by a geographical bounding rectangle, it will be far more efficient to use Google own DB and query it by street names.
I know how to register to pan and zoom events.
I know how to calculate the viewport coordinates.
I know how to color a single street.
How can I get a list of all streets visible in the viewport?
Any other solutions or architectures are welcome.
The preferred solution will not use Google DirectionsService nor DirectionsRenderer since they slow down the map.
My understanding is that what you are asking is not possible from Google API's. Reverse geocoding inside a polygon is not a service they offer. There are some posts on other sites (e.g. https://gis.stackexchange.com/questions/22816/how-to-reverse-geocode-without-google) with the reference gisgraphy.com looking like a pretty neat reverse geocoding tool.
This still does not address your all streets in a polygon problem however. I think your only option would be to get your hands on the data (Open Street Maps) and write the code yourself. Further - if you are going to do this for a large area I would take an approach like I recommended here with grids: https://stackoverflow.com/a/18420564/1803682
I would create my grid elements, and for each street calculate all the grids to which it belongs and store in the database. Then when you search a polygon, you would calculate all the grids the polygon overlaps, and can then test the subset of road data in each of those squares to determine overlap.
I looked into this and abandoned a similar requirement a few months back and still have a desire to implement it. Most of the point/line in polygon work is happening on data created in my application (i.e. not street data) and right now that is the only data I will be including. What I am trying to say is - I hope someone gives you a better answer.
Update:
For what you are asking I still believe you will need to use a mix of your own database based on OpenStreetMap and some kind of grid analysis carried out in advance. If you have some time to commit to the project this should not be too awful to process. The database will be large, and the calculations needed will likely require a significant amount of one-time / upfront processing time. As far as highlighting routes/roads/whatever within the viewport, there are lots of way to accomplish this using the API - example here which I found useful: polyline snap to road using google maps api v3
Also useful: http://econym.org.uk/gmap/snap.htm
Note that one way streets may give some grief if using the directions api to snap to a street and you will likely have to watch for this and correct or reverse the start/end points.
Google would recommend using it's Geocoding Service in order to populate your data base with the co-ordinates. You can then use the LatLng Bounds Class method "contains" to check whether your points lie within the viewport. The advantage of this approach is you only need to geocode the information once and then store this, versus sending coding requests each time the viewport changes.
An alternate efficient way of displaying this kind of data may be to use google fusion tables. this greatly simplifies the integration of the data with the map.
I want to divide the earth into separate regions I can assign objects to.
Basically, I have a map (from Google Maps or somewhere else, the exact source is not important). On this map I want to define regions of different type, e.g. you might have regions of type A, B or C - or even regions without a type.
My question is: How could you implement this? Which techniques to use?
Basically, several options come to my mind:
Project the map to a 2D rectangle using a map projection (sub question: Which one to use?), and define the regions as rectangles. The clear advantage is that besides the projection I do not have to care about complex mathematical formulas. The drawback is that I need to project every input to the projected map.
Use a sphere, and calculate the area of the region using trigonometric functions. This is definitely more work regarding the formulas, nevertheless you do not need a projection.
What other possibilities are there?
What are the individual advantages and disadvantages?
The reason why I want to do this is because the end user may use his or her mobile device to get his / her current location. Then the app should be able to get what kind of region the user is in.
Any ideas?
Most likely maps application uses a spatial index to subdivide a map. A spatial index is a space filling curve. There is also a more complex curve like the hilbert curve. Microsoft bing maps uses a z curve. It's also possible to use a 3d spatial index but it's very complicated. But most likely it's just for tiling and faster query the map.
http://msdn.microsoft.com/en-us/library/bb259689.aspx
I have good news for you: the maps you are looking (google maps et al) are already 2d projected so you don't have to worry about projections.
Good luck
I would like to have the possibility to tell if a GPS location is in an inhabited or uninhabited zone.
I have tried some reverse geocoding services out there, but all of them proved useless, because they select the nearest address possible. (I understand why this should be so, it is useful for the purpose of reverse geocoding)
I have noticed in Google Maps, when I search for a city, their boundaries are selected in red dotted well defined line. I would love it to use this, or something similar.
Is there any possible way that Google maps can provide such a service, or something that can solve my problem.
Are there any other web solution or databases that you know of that can give me this information ?
Or maybe I can use any of the reverse geocoding solutions with some parameters (such as restricting the size of searching) to determine if the location is or is not in a populated area?
If you will not find a public service then it gets interesting, and expensive in terms of developping effort.
Public data (world wide) is only available from OpenStreetMap, i think they have such a layer (could be named Land_use (rural, etc.)) This layer is usually used to color a map, look at openstreet map Web page if you find a suitable coloring, that coresponds to your task. (E.g look at green, or gray).
These data are stored in polygons, you would have top extract these polygons (i asume millions of them). Ten you need a fast searching spatial index, like a region Quadtree.
Then you do a "point(lat, lon) in polygon" call, and get the polygon related to your position.
Probaly not all that polygons will fit into main memory, so you must load them on demand (e.g by country).
A variant of this approach is to use a geo spatial database like postgres to store that polygons, and do a DB query.
With that approach most work will be extracting the polygons from OpenStreetMap DB file.
More acurate is data from TomTom, but these can be really expensive.