In the application of road navigation, it is often necessary to express the flow and congestion of the road through the thematic map, e.g, green means smooth, yellow means amble, red indicates congestion. When viewing map in large scale, generally the roads include main roads, auxiliary roads, ramps, which can be displayed by a thematica map according to the road traffic congestion data field information. In the case of small scale, generally the roads are expressed with two-way, and they does not show the auxiliary road and ramp traffic congestion, only show the main road in two directions, in this case, in order to avoid road overlap, it’s needed to make offset for the roads.
The example is based on the NavInfo data, to introduce how to make real-time traffic road map. It mainly includes two parts: