I have work with a ~23MB kml file. The task is to show the polygons (~5000 shapes) online on a google-map and show some information in a sidebar when a shape is clicked. All the stuff can be done in JS I think. So if I use the large kml file on the page it will load all the 23MB at once and is very slow. It is not necessary to show all polygons at once, so it would be possible to show only parts of it at a certain zoom level. What strategies are common to solve this issue?
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I've embedded google maps several times, only doing basic stuff though.
Now I need to overlay districts over a city. I worked hard to get, parse and adjust all the coordinates for all districts and I don't want others to copy my coordinates.
Can I display the overlays, but prevent users from reading the KML coordinates ? Is there a way to embed them other than having the path visible for everyone in the javascript api block ?
Try using a FusionTablesLayer. You can import your KML into a FusionTable, and prevent it from being downloaded, but display it on a map. People will be able to look at your coordinates, but it will be difficult (but probably not impossible) to grab them.
I have searched high and low for just a snippet of java script code showing this, but all I'm trying to figure out is how to toggle parts of a KML, mainly folders, using check-boxes or similar. Currently the KML is loaded to the plugin using a networklink.
All of the examples I find want you to have separate kml files for everything, but given the sheer number of assets I'm dealing with that wouldn't be feasible. I know this is possible. All I'm looking for is just that one example of "click this, then this "folder" appears".
Any help is greatly appreciated!
The question is pretty descriptive.
I am working on a website that provides locations for filming.
All the data in the site is currently stored in a MySQL database including geocode data for google maps.
I need to show polygon areas for the different london boroughs that has locations.
I have all the data as kml files, idealy i would like to store this in the MySQL database.
I have had success using fusion tables to display this data, but it seems silly to me to have to have this data duplicated on google just to use a fusion map layer, can i simply use a kml layer to render this data rather than having to create a fusion table and rendering it from that?
If so, is there a resource someone could point me to for more information?
UPDATE:
Thank you for the responses so far, i thought i would update the question with a little more info .
I eventually want to have all the areas displayed at the same time on my map and then when an area is clicked on ideally it would take you to another page on the website showing locations for that specific area.
I had initially tried using KML layers but i was getting errors saying my KML was invalid.
The KML was initially stored in a field in my database table, i think probably the errors were due to me not understanding exactly how google read in the KML data.
Using polygons would be far simpler to implement as i can get this data via JSON and then render the polygons from that.
I know now its not possible to have info windows with polygons, but i would just prefer to jump directly to another website page with info for that particular area using a click handler rather than show an info window.
Alternatively as suggested showing a tool-tip with a brief description of the area and a link to the page would be better, how the tooltip itself, is it possible to render on top the map?
I am slightly worried that I will reach the layer limit for the KML.
Is it possible to have multiple polygons rendered with KML on one layer, or do i need a separate layer for each clickable area?
The Google Maps API provides a pretty straightforward method to draw polygons.
Basic Example:
var polygon = new google.maps.Polygon({
map: your_google_map_instance,
paths: array_of_latlng_points,
fillColor: "#336699",
fillOpacity: .5,
})
EDIT: For this approach, you would need to parse your KML files (sorry, must've missed that when I first read it). You can import the KML files to a KML layer
You can overlay Polygons using KmlLayer, FusionTablesLayer (as you know), or native google.maps.Polygon objects.
KmlLayer and FusionTablesLayer render them as tiles, so for lots of Polygons (if you only need click events) will be more efficient. There are limitations on the number of KmlLayers that can be displayed on the map at one time and on FusionTablesLayer (but those don't seem to be causing you problems).
There are also third party parsers available for KML (geoxml3, geoxml-v3) which will take your KML and render it as native google.maps.Polygon objects. For lots of Polygons, this will be less efficient than tile based rendering, but it does allow mouseover/mouseout, and changing the properties of the Polygons dynamically.
You could also try data layers what have lots of events so you can display tooltips, info window, status text on various mouse events.
See samples in documentation:
https://developers.google.com/maps/documentation/javascript/datalayer
If you have many polygons (where the actual value of many depends on multiple factors, can be anywhere between 100 and 1,000) the best is to use a built in layer type. The fastest are the ones rendered on server, e.g. kml layer because this doesn't create hundreds of DOM elements in browser but still exposes click events so infoboxes can be displayed for each item.
In the worst case you can implement your own rendering with an image map, obviously by using an existing library like mapnik.
https://developers.google.com/maps/documentation/javascript/maptypes#ImageMapTypes
Do you have any idea where I could find kml file with simple contours of the continents?
I've been searching for it and all I've managed to find was KML that has more thatn 6MB. It contains too much details. I need something really simple. Just 7 continents. Nothing more.
Thanks
By "contours" do you mean "borders"? A search for "countries" at Google Fusion Tables gave a number of results, including some Natural Earth imports, such as this 1:110m simplified borders.
You can view a map of that table by clicking Visualize -> Map (zoom in a few levels to see the polygons). From the map view you can click Export KML to download a KML.
my problem is with XXk (aka XX000) markers, atm I have 7k markers and will be more, and more, problem is in marker database, because atm this is 4MB (link to my DB http://tinyurl.com/ybau9ce) and problem is, how load that fast? for example DOWNLOAD only this what are show now, DOWNLOAD because load I have with ClusterMarker and problem is not with java but with download that database I think...
http://code.google.com/apis/maps/documentation/overlays.html
find the part about the marker manager
quote from that "The manager monitors the map's current viewport and zoom level, dynamically adding or removing markers from the map as they become active."
dynamicly doing this would require a database with all the markers.
Theres a good explanation on how to do that on the link under here.
code.google.com/apis/maps/articles/phpsqlajax.html
you are able then to dynamicly generate those markers that are in the boundaries of the current zoom.
There will be some events after zooming or moving the map and you can then trigger on that
and find out the boundaries of the current view.
Would that be helping solving it?
Why would you want to download all that data at once? You cannot visualize 7K markers at once on a map imo.
I don't know what the goal of your question is, but I would have only the data uploaded that is in focus, e.g. on display and visible.