I need a 'polygon' selector type functionality. Basically, the ability to drag lines to form multiple polygons; pref with the ability to edit the 'points' of the polygon after the shape has been 'closed' (but that's secondary) and/or move the polygons...
I generally dislike 'reinventing the wheel' and I figured I'd find tons of examples to work with, but I was wrong...
The polygon tool in Google Maps is just about perfect, but has anyone utilized it outside of GMaps? (I recall it required a GMap as an attribute from my work with Google Maps). Before I roll up my sleeves, I just want to ensure there isn't something already made (this is a very small part) - so if (a) Google Maps Polygon object is usable without a map, or (b) there's another library/project I'm missing please let me know.
Fabricjs is an option you can check.
Have a look at D3.js which has a great api for visualizing data and geo information. Besides the standard one-/two-dimensional brush there are plugins for more advanced types of brushes:
Polybrush. Providing a polygon brush.
lasso. Lassoing a selection by freely drawing a line path.
Related
I am using Overlay Shapes with Google Maps API V3 using Google’s Drawing Manager. I basically allow the user to draw a polygon and save it to a database. They can then edit these polygons at will or create new ones.
The issue I am having is that often new polygons will completely cover existing polygons. Then the user cannot select the polygon beneath the latest one.
I wondered if anyone had managed to devise a script that enabled a user to cycle through the selection of every polygon in a potential stack under the mouse cursor (or pointer/finger...)
The attached image illustrates the predicament. Ideally I'd like something like CTRL+Click to select the polygon beneath the currently selected polygon.
No idea how to even approach this and I could not fine any examples in existence.
Thanks in advance.
You can try using control click to change the z order.
I wanted to ask you about the way to make spatial interpolation in google maps API. This means- I have values for some points inside an area and want to recalculate values for every point in this area (and create an raster overlay).
In "offline" GIS softwares, there are more methods to do this. For example Kriging (http://en.wikipedia.org/wiki/Kriging).
Thanks for answer
There is no real practical way to do such a thing. Spatial Interpolation is something you really need a full-blown GIS to accomplish. It requires storing, analyzing, and presenting data in way that ArcGis or QGis is best suited for. There is some new feature in ArcGis Online that works with Google Maps API but I don't know much about it and am unsure if it would be any help for you but a link is here.
I know, its not something geostatiscically correct, but I have made this:
- I have created a net of rectangle polygons.
- I have connected all my points to polygon they lie and have made mean value for polygons with at least one point
- I have checked every polygon without points and at least 2 neighbourly polygons with points, and have made mean from this neighbourly values
- I have checked again all my polygons with values and at least 2 neighbourly polygons with values and smoothed origin values according to the neighbours´ values.
I am attempting to make a simple PhoneGap app that will allow a user to input lat/long points and bearings and calculate their estimated intersection, along with a measure of error. I would like to display the lines, intersection, and an error elipsoid on a map or at least a grid of latitude and longitude lines, so the user can visualize the accuracy of the point. The tricky part is that this will be used for wildlife tracking in areas where the user may not have cell service. Is there some sort of Javascript plugin that will make a lat/long grid available for me to draw georeferenced lines and shapes on? I would love to use something like the Google Maps API, but that clearly won't work for offline use. I've Googled quite a bit, but I'm not sure where to start with this or if it's even feasible at all.
This program is similar to what I'm trying to achieve: http://www.locateiii.com/
Any ideas are greatly appreciated.
I'd use d3.js and http://code.google.com/p/gmapcatcher/ something like this where you can keep the google maps offline. If that's not feasible you can always us D3 with a svg of the map.
I ended up using OpenLayers with OpenStreetMap tiles prepared by Maperitive. Simple and works well with PhoneGap.
I'm looking for a JavaScript library that allows me to build SVG maps from locally hosted shape data (to allow users to use the application without internet connection).
1) Where should I be looking?
2) Is GeoJson a good candidate for shape data?
3) Where do I find shape data for country borders and (1-level deep) subnational entities?
If the library also supported drawing circles with the center point at specific lat/long coordinates, that would be a bonus :)
You could try to use jVectorMap for that. It has a converter to generate custom maps.
Raphaeljs should meet all your requirements. There is an actual example of a map right here http://raphaeljs.com/australia.html. Of course you'll need to provide the appropriate data.
I am familiar with how to draw circles and polygons on a Google Map using the javascript API. However, I've been looking at some android apps that allow you to "touch and draw" a freehand area on a map, not a collection of polyline/points or geometric shapes.
Is this functionality accessible to the js API? If so, how? I only find documentation on the polygons etc.
Note: this type of functionality is not what I'm looking for! Clicking at multiple points to define an area is fine, but I'm trying to do a real "drawing" style.
Thanks