In the application of road navigation, thematic maps are often used to express the situation of road congestion. Use green for smooth traffic, yellow for slow traffic, and red for congestion. View the map when the Map Scale is large. Generally, the main road, the auxiliary road and the ramp are displayed separately. Select Fields to make the Unique-values Map according to the congestion of the road data. In the case of a small scale, the general road is displayed in both directions, and the road conditions of the auxiliary road and the ramp are not displayed, but the congestion conditions of the main road in both directions are displayed. In the case of a small scale, in order to avoid the overlap of the road lines, the road lines need to be offset.
Based on the data of NavInfo, this example introduces how to make the real-time road condition map in detail. The example is applicable to the data of NavInfo. The specific content of this case includes the following two parts:
