I have data consisting of parts of road segments of a city, with different number of visits. I want to plot the data on a Map and visualise it in the form of a heatmap.
I have two related questions:
I have the data from Open Street Maps (OSM) in the form of pairs of node ID's, where node ID correspond to the unique ID being assigned to a point by OSM. I also have a mapping for each node Id to its corresponding coordinates. Is there any Leaflet or Mapbox utility or plugin, which can plot a trip / highlight the road segment using 2 node ID's. I can always do it manually (by using the coordinate mapping and converting it into GeoJSON), but the problem occurs with the line width -- I have to make it exactly overlap with the width of the road, so that it seems that I am highlighting a road segment.
Is there any plugin / utility for Leaflet or Mapbox, which can be used for plotting polylines or geojson as heatmap efficiently? My current approach is calculating the color for each polyline and encoding that as a geojson property. But the problem is that with the increase in the number of lines (> 1K) the rendering becomes a pain and the method is not feasible. There are some plugins for Leaflet out there for plotting heatmap, but all of them are for points only and not lines. Any approach using WebGL would be really great.
An approach which I thought of could be converting my data into a shape file, upload to Mapbox Studio and use as a layer directly. But I have no idea how to go about doing that i.e. creating a shapes file, encoding the information in such a way that the complete road segment gets highlighted in the correct color.
Related
I'm trying to create an experience where I have a couple of detailed 3D models of buildings on the map with extruded building footprints of neighboring buildings via a vector tile source. The 3D models would be the main focus point and the extruded footprints would be for reference. One challenge I'm running into is that I have a global building footprint layer and it has a footprint for the 3D buildings which doesn't match up perfectly. Additionally, when extruded, it ends up merging/overlapping the nice 3D models.
I'd like to be able to hide the individual footprints that overlap the 3D models. My original thought was to grab the bounding box of the 3D model and then use the new within style expression, but it looks like this will only filter points and lines, not polygons. The building footprint polygons have no unique information in them that I could use to filter on.
I know I could monitor map movements and query the rendered features and manually detect intersecting polygons, but since there is no unique property on the footprint, I can't filter or use feature state.
Any ideas of how to efficiently avoid rendering individual polygons in a specific area that come in from a vector tile source?
It is a common issue that the buildings layer in Mapbox Streets don't contain any unique attributes to allow filtering or rendering differently.
The best solution is usually to source a different buildings layer, and in this case, remove those redundant buildings in pre-processing.
I can think of one rather crazy workaround that might work here, although the performance may be poor.
Add the building layer with very low opacity, of type fill, essentially invisible. (Maybe invisible would work.) Call your main source buildings`.
Create a secondary building source of type geojson, and a secondary fill-extrusion layer. Call this source buildings-copy.
On map move or moveend, use querySourceFeatures to obtain a copy of all buildings.
Process this copy using Turf to remove the buildings you don't want, and call setData to set the copy as the data for buildings-copy.
You may need to do some clever caching to get reasonable performance.
I'm fairly new to Leaflet library and I would like to ask if following functionality is somehow already implemented in Leaflet(or maybe in some other library).
I've found the following example which does clustering based on markers on the map and map also contains choropleth areas displayed.
My question is - Is it possible to do clustering based on choropleth data? Like if I have geojson data for some regions and would also have geojson data of subregions for every region. So if I do zooming then those subregions would collapse to big regions or big regions would be divided to small ones?
Big thanks for any advices or links!
No, because clustering algorithms work only on point data.
You might want to just hide the regions and display the "subregions" when zooming in.
If data becomes too dense when zooming out, consider making the union of the polygon geometries to display that instead. A naïve algorithm would be search for the smallest polygon, then search for the smallest neighboring polygon, replace them by their union, repeat. Stop the algorithm when the smallest polygon is larger than a given threshold.
I'm trying to build a home value Heat Map for a city using Folium (a python library that uses Leaflet to plot geo data). My Dataframe contains Latitude, Longitude, and Price (variable which is going to act as weight). Cheap areas should be green and expensive, red. The problem is that some poor regions with many dots seem to be more expensive, because those dots overlay each other and turn that region red. The method has some parameters to switch, but any of them solved my problem. Does anyone have a way to overcome this or an alternative library to make interactive heat maps using python?
Is it possible to apply fill-extrusion for a GeoJSON LineString feature?
Basically I'm looking for a way to draw lines (can be 1 line or multiple connected) in a 3d mode with z-offset.
If that's not possible, maybe this can be done with a polygon instead?
Like, converting my lines to polygons (how can i do that?)
What you're asking for isn't yet implemented, but ticketed in Mapbox GL JS at https://github.com/mapbox/mapbox-gl-js/issues/3993.
For now you'll need to opt for your second suggestion of converting the LineString feature to a Polygon. You can do this with turf's buffer function http://turfjs.org/docs#buffer.
The whole line/polygon will be offset at the same height, so depending on your application you could use turf's linkChunk http://turfjs.org/docs#lineChunk to get it broken up into smaller features which you assign different height properties to.
I'm working on a project using Leaflet. For this project I've created an interface to draw all the roofs of a large city as polygons. A lot of scripts calculate the surfaces, the addresses, the orientation and so on... I'll store each roof's datas in a geojson file (or files). We expect to get about 10 000 roofs or more. I don't know if Leaflet displays only visibles polygons depending window's boundaries or if all the polygons are drawn, and my problem is to find the better way to do this storage.
In one geojson file. It may be a problem because the 10 000 roofs are computed in the same time and waiting for polygons loading may be very boring for users.
In separated geojson files: for each roof I can approximatively calculate the coordinates of its center and put this roof in the right geojson file depending the lat/lng. By this way I can create (say 20 or 50) differents geojson files and call the right one depending boundaries. Then the question is: to create all the polygons, is it better to call the 6 (or 8 or 10) geojson usefull files for the area on screen, or is it better to create a new dynamic geojson file?
All the roof's datas are stored in a database or in a XML file and I have to detect boundaries and automatically create a dynamic geojson file. But each time user scroll or darg or zoom the map I'm supposed to recreate this unique geojson file...
Do you ever have a similar problem to solve and how do you solve it ? Thx.
I think the second scenario is the most robust, you need tiled GeoJSON tiles. Have a look at Leaflet Plugins. There is one called TileLayer.GeoJSON. Some links on how to create these tiles are on OpenStreetMap wiki.