How to get placemark info from static kml - javascript

I want to get information from static kml file or mapinfo tab file i.e I have a kml/mapinfo tab file that i open on google earth/mapinfo and it shows multiple placemarks but i want to get coordinates of all the placemarks that lie within 1km circle from my required single placemark. How it can be possilble on google eatrh or mapbasic code?

What you're looking for is a basic "point in polygon" analysis function available in most GIS software, but not in Google Earth or Maps. If you know how to use the free QGIS, you could do it in there, though the steps required are somewhat complex if you're never used GIS software before. You'll need to bring in your KML, generate a new file with the single placemark and generate a circular "buffer" at the desired distance, and then select the features in the KML which overlap with the buffer. And you'll need to manage projections to make it all work correctly.
If you have a large enough KML to warrant the work, or need to do this many times, then it's probably worth figuring out how to do it with GIS software. If it's only a small number of placemarks, and you only need to do it one or a few times, then get Google Earth Pro (it's free), use the Measure tool to draw a 1km circle, and manually select the points inside it.

Related

Google Maps Markers in wrong location, but lat/lon appears correct

I am using custom markers to show a semi-live view of the location and orientation (heading) of certain vehicles of interest overlayed on Google Maps. (In my case, I'm depicting aircraft, the same way Uber does for cars, or how FlightAware does for commercial flights).
The coordinates for the markers are being broadcast in JSON format to participating browsers from a server that I control. The JSON data is processed by a JavaScript function at the browser to create / update the markers on the Google map. The refresh (broadcast) rate can sometimes be as fast as once every 2-seconds, or as slow as once every 30 seconds, depending on the particular user's needs of the moment.
Sometimes, it is possible (and valid) for two markers to be thousands of miles apart from each other. For example, one marker could be in Montana, and the other could be somewhere in Africa, and this is a valid condition.
However, sometimes, when I am zoomed into a region of the world so I can look more closely at one marker, a "ghost" marker appears nearby that "isn't really located there". The ghost marker is labeled as one of the other markers that may be hundreds or thousands of miles away, but it's showing up in my zoomed in view for some strange reason. If I momentarily zoom in our out, the ghost disappears, but it may re-appear again.
Interestingly, the ghost image has the proper orientation for the vehicle it represents, but it's just located in the wrong part of the world.
Are there any special things I should be doing when I'm updating multiple markers separated by large distances so they don't show up like this in the wrong place?
I have traced this as far as putting console messages in the browser so I can see the lat/lon of each marker being depicted. I output the latLng object just before it's applied to each marker, and the lat/lon I see in the console log is correct, even when the actual marker shows up in the wrong place.
I don't know if this is a contributor to the problem, but the marker images I'm using are custom PNG files, not standard Google makers. Has anybody run into this before?
As I can see there are a couple of issues reported in the Google issue tracker very similar to the one you described here.
Have a look at them:
https://issuetracker.google.com/issues/74225068
https://issuetracker.google.com/issues/73864685
Feel free to add your comments and star the issues to subscribe to further notifications from Google.
Please note that these issues were reported for the experimental version of Google Maps JavaScript API. Double check which version of the API you are using. Probably loading the release or frozen version will work as a temporary workaround for you.
For more details about versioning model of Google Maps JavaScript API please refer to the documentation:
https://developers.google.com/maps/documentation/javascript/versions
I hope this helps!

Manipulating neighborhood polygons using the Google Maps API?

Google maps does a very good job highliting the neoghborhood boundaries polygons:
The underlying polygon data is very good. It's definitely better than Foursquare's Quattroshapes.
Since I don't think there's a way to extract this data from Google, I thought that maybe it would be possible to show / highlight and manipulate these polygons as first class objects inside Google Maps using the Google Maps Javascript API?
What I would like to do is i.e highlight only a subset of the neighbourhood polygons per city, change their fill colors based on my own data, etc.
Another option would be to get the polygon data from Google and draw the polygons myself, but I'm pretty sure it's not really available. Does anyone know?
Thanks!
Unfortunately, you cannot get the information directly through the JavaScript API. If you can find KML data online (or make some yourself), it can be loaded through google.maps.KmlLayer.
It is pretty easy to make KML layers in Google Earth. So if you only need 1 city, it may be a good time investment to make.

highlight building google maps v3

Im trying to highlight specific building within a map using the google maps v3 api. I was wondering if anyone had any idea how to do this. I've been looking through google api documentation and come across nothing at the moment.
For example: http://goo.gl/maps/GyrDB - This is a map of a section manhattan, as you can see the 3d building. Im trying to highlight specific ones on hover.
Thanks :D
If you have information about where the building is, then you can use a Polygon to highlight it. If you don't have information about where the building is, then you are probably out of luck. The Google Maps API doesn't have any way of interacting with the map at that level.
Now, I suppose that one thing you could do is:
download the Google Maps tile,
find the point in the image that the user clicked on,
do a flood fill of that point with some awful colour,
set to clear all the pixels which are not the colour,
overlay that image on top of your map
You would also need to be clever about buildings which lie in more than one tile.
HOWEVER, this might run you afoul of the Terms of Use. I know that they disallow modifying the artwork; I am not sure if this would count as modifying the artwork; you'd need to look carefully at the TOU and maybe ask a lawyer. Or ask Google. (Don't ask me, I am not a lawyer.)
In many countries, every building is a cadastral parcel and there Web Map Service (WMS) layers showing them, provided for free by state bodies.
Using these layers, you can get building polygon coordinates. For ex: https://snag.gy/WtU7ZT.jpg

Color in Country

I have a written up HTML file using the Google Maps API v3.
All I want to do is color a couple of countries, for example, color in China and Canada to red. What is a simple solution (that doesn't involve Polygons and thousands of coordinates) to color in countries?
After browsing previous StackOverFlow questions, there seemed to be three common solutions. However these 3 solutions do not seem appropriate for my situation.
Charts API
-I don't really understand if Charts API is a good solution for me because I have already have a file using Google Maps API. Unless Charts can be applied over my map, or synchronize with the map, this does not seem to be a valid solution.
Styling (With Styling Wizard)
-This wizard (as far as I know) deals with the style of general characteristics, like road, water, population, etc. Unless someone can show me how to assign a specific country a color, I do not see how this can work.
Polygons
-I saw the example of the Bermuta triangle and other people have suggested to get the coordinates of the perimeter of a country and create a polygon. This may work except I may need a thousands of coordinates in order to fully outline China. Perhaps there is a more simple method in which I can color in a country?
Use either FusionTablesLayer or KmlLayer.
Both take kml formated geographical data and render it on tiles, yielding better performance with complex or large numbers of polygons.
The Natural Earth data set is available in Fusion Tables, and contains most countries.
This might work for you if coordinates generated automatically in different resolutions depending on your requirements. all you need to do is to load an appropriate GeoJSON onto your map. See here for the complete answer which is done just by adding a couple of line of codes.

Library for visualizing users on map over time

I have data corresponding to user events with (location, time). I would like to visualize these on an animated map. Maybe with points of light appearing when an event happens (with multiple events in the same place making a brighter dot). Double points for animating the day/night regions on the map at the same time. Is there a javascript library good for visualizing such data?
The map on the right side of this visualization written in processing doesn't quite fit my description, but would also work well.
I found that d3.js worked really well for the project. The geo module made it easy to draw a world map (with data from data/world-countries.json and a mercator projection) in an svg element. First, I pre-processed the data to put the users in "buckets" of gps locations. I added a circle for every location, and changed its radius for how many users were in that bucket.

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