Let's say you want to build an app where people can find out whether the location the users are on has a risk of being flooded. You want to be able to create flood zone areas on the map and compare the user geolocation relative to the area. How do I do that with google_maps_flutter? or is there any other way to do it with plugins in flutter?
What I have in mind right now is to create polygons on the map and perform some geometric operations with it (if that is even possible). I have Esri SHP files which I will export to json and parse it in flutter and then use the results to draw polygons of the areas.
no code just yet..
You can make use of 'overlay widgets' in Flutter. You can draw, say a circle, indicating a flood zone with colour and radius in accordance with the probability (or other parameters).
Depending on how you want to display, you can create a separate UI control to display the comparision with reference to the user's geo-location.
Related
Am using leafletJS for showing offline maps using openstreet tiles and its working fine. We need to use atlast tool to generate tiles and able to do that. But how to handle case that if generated tiles are not matching with latitude and longitude which are coming from services then in leaflet is showing markers but background map tiles are not loading (I know it wont match so its not showing :) ) but is there any way / approach which I can figure out that latitude and longitude provided are not in range or in sync of map tiles generated for offline so that I can show meaningful message to end users and accordingly user / admin will take actions?
I can imagine three approaches to this:
If you know which tiles you are generating (often times you are generating tiles in a bounding-box) you could hardcode that bounding-box and check if the given coordinate is inside or outside before adding the marker or jumping to the coordinate.
This question (leaflet - tile loading - error event) details a way to detect when Leaflet can't load a tile (for whatever reason: tile does not exist, no connection, ...). Maybe you could inform the user using that tileerror event.
You could convert the coordinate into its Slippy-Tilename equivalent and try to manually request that tile from your server / storage (for example using the Fetch-API). The conversion process is detailed (with code!) on the Openstreetmap-Wiki (https://wiki.openstreetmap.org/wiki/Slippy_map_tilenames#ECMAScript_.28JavaScript.2FActionScript.2C_etc..29)
I want to label stations on my map, and I would like to clusterize the stops at different zoom levels to filter them down. So as you zoom out all you get is the start and end, and then finally a single label start->end.
How do I render a text label on a vector tile ?
I could fetch the stations as a geojson and reload on zoom change if there's no easy way to do this with tiles.
Is there a reason you need to encode your data differently per-zoom-level in the tiles or are you mainly concerned with displaying data differently per-zoom-level? If the latter, I would recommend looking for an approach that focuses more on styling the vector tiles you already have rather than trying to generate those tiles in a more complex fashion. You could try using a zoom function to style your data. If you're using Mapbox Studio, you can also set zoom-specific style rules in the Studio UI, which is the route you'll probably want to go if you're using Leaflet (I see the Leaflet tag in your post but it's not entirely clear what your implementation looks like).
If the former, you may need to use a tool like Tippecanoe. This route will likely be a bit more complex, but gives you fine-grained control over how your vector tiles are generated. Keep in mind that once you've created your tiles using Tippecanoe, you'll still need to style them somehow.
I want to create a static google maps image which displays buildings (and buildings only). I looked through the Styled Maps page on static maps stylings, but I couldn't find an option for buildings in particular.
Please note that this should also work in less populated areas, so simply turning the landscape one colour and showing the roads in another does not suffice (like done in this image).
Is there a way to create such a map?
The closest feature for buildings would be the landscape.man_made feature which selects structures built by humans. You can also experiment on other features that may suite your needs such as points of interest.
For features that you want to hide from the map, you can set the style to visibility:off for that specific feature.
Here's an example that changes the stroke color for all man made landscapes and hides all roads:
https://maps.googleapis.com/maps/api/staticmap?size=512x512&zoom=17¢er=Brooklyn&style=feature:landscape.man_made|element:geometry.stroke|color:0xff0000&style=feature:road|visibility:off&key=YOUR_API_KEY
Note that the sample uses the element geometry.stroke which selects only the stroke of the feature's geometry.
Hope this helps!
I'm using Mapbox GL JS. Is there any way I can style my base layer to look like the Mapbox Light example, but showing only the UK?
I assume I would use Mapbox Studio to build my own base layer, but I can't see any way in Studio to filter by country.
If that's not possible, is there any way I could show labels on the UK only, and show other countries as filled polygons? (As per this unanswered question.)
Unfortunately it is not possible to filter by a certain geography when selecting the data source for a layer. If you're working with Mapbox's tiles, they'll always cover the entire planet.
There is the possibility to restrict the map to a certain (rectangular) bounds, with the map.setMaxBounds method (https://www.mapbox.com/mapbox-gl-js/api/#Map#setMaxBounds). This might work reasonably well since you want to restrict the view to the UK, but might not be suitable depending on the geometry you want to restrict the view to.
As a workaround you could create a dataset and add a polygon that covers the entire planet except for the extent you want to show in your map. Then add this dataset in your style as the top most layer and style it with whatever you'd like the empty space in your map to look like.
The workaround has been also suggested in this SO answer, if you can get maptiles for the UK only (the SO answer gives a link, but for Germany) you can
upload them to Mapbox as a dataset, export it to tilesets, and then
to a map as a layer. Delete all other layers
You have also the possibility to Style a single country in Mapbox
studio ref this tutorial. The other countries are still shown, but you can style your map in a way to highlight UK
There is a option that allows you to show only one country highlighted. But drawback is, you lose all the layers and tile-level details. Here is the link https://www.mapbox.com/videos/how-to/map-a-single-country-in-mapbox-studio/.
But if you want to include the tile details as well as whole world map but in that map only one or two or custom amount of countries highlighted, then, from above link of Natural Earth download the zipped file of ne_10m_admin_0_countries and upload.
Go back to your map style, and instead of making a blank one. Add another layer of ne_10m_admin_0_countries in your current map. Select the country in the filter option (in same way as shown in video). And change its opacity. That's it.
Hope it helps. Have a great day.
I am developing a Map based iPhone application where I have to draw a map of any specific region depending upon the current location of that device.
Client is supplying me the .shapefile consisting of all the co-ordinates and data to draw the map.
We can store the shape file on the server and i think to draw the map on device with the data presented on .shapefile I need the tiles with different zoom level. So on the server side I have to convert the .shapefile into tile based file.
But I don't know how to do that conversion.
Can anyone please guide me?
Thanks in advance.
Ritz
Its a lot of work.
First, shapefiles only define the geometry - you need to decide what the features are going to look like. Are they points, lines, or polygons? Do you want them all in the same colour, or depending on their attributes?
Then get mapnik or TileMill and learn how to use that. Do you just want to present the shapefile, or do you want that on a base map? In which case you'll have to generate a transparent tile set and do raster image overlays in your application.
Is it the whole world? And to the same resolution as Google Maps zooms? Get a big bank of disk storage.
http://mapbox.com/tilemill/
http://mapnik.org/
Personally I'd look into converting the shapefile into a vector form that you could render on the client - GeoJSON perhaps. Then serve that.