HERE Maps API - How to create a custom overlay
This article explains how to create a custom overlay and add data from your own tile server to the map.
For extremely large data sets, it no longer makes sense to add each data point as an individual marker, image or polyline. In situations such as displaying weather or traffic conditions over a map, it would be less processor intensive to retrieve pre-built images from a tiler server rather than re-calculating and adding a large number of mapObjects on to the map display. The cost of making a few extra round trips to retrieve data from a server will be much smaller than the equivalent client side processing of adding hundreds of thousands of objects onto the map.
Through using the functions in the Code Example it is possible to display graphical data on a Nokia Map, an extension to cope with multiple bars per chart (shown below) is also included - feel free to adapt the code to your own use.