Is there any general advice when to use KML layers or the Javascript API? There are several needs for the app. I need to display markers for moving object on the map. These will be refreshed every minute in average. But there will be a lot of static markers to be displayed on demand. These are just markers. But in another screen I need to draw the driven routes.
Actually I'm not sure what's the best way of displaying all the needed data. KML? Only get the data and to the rest by the API on the fly? Generate the code on the server and just upload it to the browser. What would be the best in terms of performance and and easy usage for the developer?
I think javascript layers are faster than kml.
(The fastest speed is to generate image tiles - but that takes a lot of time and needs to be done statically).
I'd use AJAX to generate the data on the server and send it to the API on the fly.
I think KML is useful if you want to share the data with other websites and people using desktop GIS software. It is extremely easy to use someone else's KML layer. It is much harder to use their javascript array.
Related
I have to plot 200K+ polygons (building shapes) on google map in my project. I have already plotted them on the map. But when moving the map around, it takes sometimes to render polygons. Sometimes even browser tends to freeze. I am looking for either an alternative technique to do that(Something better than Google maps) or a better way to manage polygons.
These are the constraints that I have
** this polygon information is generated on the fly and cannot be pre-prepared.
** Any viewer should be able to see all the polygons(Buildings) in a "bird eye view", so I cant restrict them into a particular zoom level.
You should use some form of server side rendering to generate overlay tiles. We do a similar thing to you with thousands of geospatial objects on a google map. We use the https://carto.com/ service but there are others available and I encourage you to do the research.
Carto stores your data in a postgres database, and then you can use cartodb.js to overlay your rendered data on a map of your choosing (leaflet, google). You can then access click/mouseover events via cartodb.js
https://carto.com/docs/carto-engine/carto-js
I should add that this is easiest for static datasets, but data manipulation on the fly is certainly possible via many of their APIs.
I have a fairly simple, and what I would think to be common mapping web mapping project to complete. I'm struggling in my selection of a web mapping API. Thus far, I've not been able to one that meets the following requirements.
Able to display thousands of points in one view without choking crippling the browser. To be specific, I'd say I would like to display roughly 30,000 points at one time and still be able to navigate around a slippy map without degraded performance.
Local maps. The web server will run on the local client, so being able to display a map without reaching out to the internet (even if it's a very basic map) is an absolute requirement.
Render dynamic data from a database onto a map (most API's are meeting this requirement).
Draw polygons directly on the map, and export the lat/lon values of all vertices.
In your experience working with map api's, do any of them meet the requirements above?
I've looked at OpenLayers 3, Leaflet, and Polymaps. Aside from reading every piece of documentation ahead of time, I can't discern if any of these would fill all requirements. Again, I'm hoping someone with experience with any API could point me in the right direction.
Thanks!
As for Leaflet:
Thousands of points: you could use one of these plugins:
Leaflet.markercluster, clusters your points into "groups of points" at low zoom levels.
Leaflet MaskCanvas, replaces all your points by a single canvas layer.
Local maps: as long as you provide a way to create image tiles (even on the local machine), most mapping libraries should work.
Dynamic data: depending on what you call "dynamic", all mapping libraries should provide you with built-in methods to display your data.
Drawing polygons and export lat/lon vertices: use Leaflet.draw plugin
OpenLayers 3 would very probably provide you with all these functionalities as well.
First, I'd like to let it be known that this is my first journey into developing mapping applications with such a large set of data. So, I am in way locked into the techniques or technologies listed below...
The Overview
What I am trying to accomplish is the ability to load my company's market information for the United States onto some form of web-based mapping software. Currently I am trying to accomplish this with Google Maps JS api and GeoJSON data, but am not against other alternatives. There are roughly 163 files (ranging from 6MB to 200KB) that I have exported from ArcGIS into GeoJSON files, and then loaded into a database (currently as GeoJSON strings). We have developed a UI that loads the data based on the current map bounds and Max/Min calculations in the corresponding records.
The problem I'm running into is the render time on the map itself, which is annoying when switching between different regions, states, or zoom levels. The API calls to load the data are acceptable in regards to the size of the data being retrieved. My boss said it is great for a proof of concept, but would like to see it much, much faster.
The Questions
What suggestions could you offer to increase the render time?
Are there better options (3rd party libs, techniques, etc) for what I'm trying to accomplish?
It was suggested by a co-worker to export the map shapes and just use the images for overlaying the information based on the coords. Any input on this?
One solution to your problem could be reducing number of vertices in polygon or polyline layers (files) while preserving feature's shape. In that way geoJSON file would be smaller and easier to render.
You can use tools available in ArcGIS for Desktop.
See
How to Simplify Line or Polygon
or
Simplify Polygon
I'm sure there are similar tools in QGIS or any other open source GIS software.
There are other solutions to your problem like prerendering data in map tiles that could be overlayed over Google Maps basemap(s). That is probably the fastest solution but more complicated.
Maybe this could be good starting point.
Just couple of random thoughts.
On one project I worked on I noticed terrible performance with geoJson I loaded via REST service.
I found out that browser's JavaScript engine had hard time parsing large geoJson responses. I finally decided to load data in batches (multiple requests). Performance increased enormously.
I noticed you use 163 files (layers?). Do you display them at the same time (no no no) or you have some control panel to switch layers on/off? If you display them at the same time then performance will suffer for sure and you should look into generating map tiles with thematically grouped layers. In that way you'd come up with couple of tile layers that you can switch on and off.
Also, if data used to generate tiles changes frequently than tiles aren't good idea. Then maybe you should look into Web Map Services. WMS generates maps on the fly from data stored in database. GeoServer supports WMS and it's easy to configure and use.
I'm working on an google map application that uses a geojson file that stores the ZCTA (Zip Code Tabulation Areas) of states. These files are fairly large and take some time to load so I was trying to find ways to reduce the loading time of the geoJson file.
I have looked at this question here:
Is there a memory efficient and fast way to load big json files in python?
so I am aware that reducing the loading time isn't easy to do.
but I came across this link that quickly loads ZCTA:
http://www.trulia.com/home_prices/
So my question is this: What has the developer done on this site to quickly load the ZCTA data? Can anyone see offhand how it was done?
You are basically asking, "how do I write the user interface for a GIS that will offer high performance?"
The developer of this website is not storing this information in a JSON and then loading it each time in response to each user's clicks. The developer is probably storing all of these objects in memory. To make things even faster, the developer has probably created the various KML files for the Google map in advance. The developer may be interfacing directly with Google, or may be using a commercial GIS that has an output format that employs Google Maps.
For example, you might check out https://gis.stackexchange.com/questions/190709/arcgis-to-google-maps.
I want to make a very clean map that only shows relevant information - e.g., only the streets that matter. I was going to just draw a map while looking at Google's, but that turned out to be very slow. Is there any way to make this easier, perhaps with some combination of mapping software and Google's API?
(If I should of put this on another SE site, please tell me)
Building upon Suvi's nice answer.
There is a very useful open-source project that collects street data for the entire globe. It's called OpenStreetMap. On their website you can extract the specific street data you need. It only takes a few clicks and bam! you got the map you need. Their data can also be accessed (perphaps easier for some) from here and here. Those links can provide you with the shapefile(map) that you need. Your newly aquired map can then be loaded in the free QGIS software that was mentioned. There you can easily select the streets you are interested in.
When you mean you want to only show "streets that matter", you are out of luck with using Google Maps. Because you have no control over the ROADMAP data that google provides. Now what you can do, is use another mapping software such as ArcGIS or Quantum GIS (which is free). Both these softwares allow you to load road data shapefiles, and you can query (select) which roads you want to display and customize the look of it to your liking.
If you want a quick approach (without having to download softwares), I believe ArcGIS has an online portal which allows you to display information you want on top of their base maps. You will still need the shapefile for your streets though. Check this link out, make yourself an account and experiment around with it http://www.arcgis.com/home/. If you click on the Map tab, it takes you to a screen which should allow you to upload shapefiles.
You said you were ' going to just draw a map'. If all you need is a very clean map, you can consider using iMap Builder which is a mapping software supports both map shape files, and custom Google maps. I have used to create some simple map projects before and worked great for me. You can use their pre-made map templates which shows just the map outlines without any details, you can then add routes / points / mouse-over speech bubbles etc as you need.