Angular Geographic Contour Map

    In Angular map component, you can use the IgxGeographicContourLineSeriesComponent to draw colored contour lines, in a geographic context, based on a triangulation of longitude and latitude data with a numeric value assigned to each point. This type of geographic series is useful for rendering scattered data defined by geographic locations such as weather temperature, atmospheric pressure, precipitation, population distribution, topographic data, etc.

    Angular Geographic Contour Map Example

    The IgxGeographicContourLineSeriesComponent works a lot like the IgxGeographicScatterAreaSeriesComponent except that it represents data as contour lines, colored using a fill scale and the geographic scatter area series, represents data as a surface interpolated using a color scale.

    Data Requirements

    Similar to other types of geographic series in the map component, the IgxGeographicContourLineSeriesComponent has the ItemsSource property which can be bound to an array of objects. In addition, each item in the items source must have three data columns, two that store geographic location (longitude and latitude coordinates) and one data column that stores a value associated with the geographic location. These data column, are identified by longitudeMemberPath, latitudeMemberPath, and valueMemberPath properties of the geographic series. The IgxGeographicContourLineSeriesComponent automatically performs built-in data triangulation on items in the ItemsSource if no triangulation is set to the trianglesSource property. However, computing triangulation can be a very time-consuming process, so the runtime performance will be better when specifying a TriangulationSource for this property, especially when a large number of data items are present.

    Data Binding

    The following table summarizes properties of IgxGeographicContourLineSeriesComponent used for data binding.

    Property Name Property Type Description
    ItemsSource any The source of data items to perform triangulation on if the trianglesSource property provides no triangulation data.
    longitudeMemberPath string The name of the property containing the Longitude for all items bound to the ItemsSource.
    latitudeMemberPath string The name of the property containing the Latitude for all items bound to to the ItemsSource.
    valueMemberPath string The name of the property containing a value at Latitude and Longitude coordinates of each data item. This numeric value will be be converted to a color when the fillScale property is set.
    trianglesSource any Gets or sets the source of triangulation data. Setting Triangles of the TriangulationSource object to this property improves both runtime performance and geographic series rendering.
    triangleVertexMemberPath1 string The name of the property of the TrianglesSource items which, for each triangle, contains the index of the first vertex point in the ItemsSource. It is not mandatory to set this property. It is taken by default unless custom triangulation logic is provided.
    triangleVertexMemberPath2 string The name of the property of the TrianglesSource items which, for each triangle, contains the index of the first vertex point in the ItemsSource. It is not mandatory to set this property. It is taken by default unless custom triangulation logic is provided.
    triangleVertexMemberPath3 string The name of the property of the TrianglesSource items which, for each triangle, contains the index of the first vertex point in the ItemsSource. It is not mandatory to set this property. It is taken by default unless custom triangulation logic is provided.

    Contour Fill Scale

    Use the fillScale property of the IgxGeographicContourLineSeriesComponent to resolve fill brushes of the contour lines of the geographic series. The provided `ValueBrushScale class should satisfy most of your coloring needs, but the application for custom coloring logic can inherit the ValueBrushScale class. The following table list properties of the CustomPaletteColorScale affecting the surface coloring of the GeographicContourLineSeries.

    Property Name Property Type Description
    brushes BrushCollection Gets or sets the collection of brushes for filling contours of the IgxGeographicContourLineSeriesComponent
    maximumValue double The highest value to assign a brush in a fill scale.
    minimumValue double The lowest value to assign a brush in a fill scale.

    Code Snippet

    The following code shows how to bind the IgxGeographicContourLineSeriesComponent to triangulation data representing surface temperatures in the world.

    <div className="sampleRoot" >
    <igx-geographic-map #map
        width="700px"
        height="500px"
        zoomable="true" >
    </igx-geographic-map>
</div>

<ng-template let-series="series" let-item="item" #template>
    <span [style.color]="series.brush">
        {{item | number: 2}} "°C"
    </span>
</ng-template>

    import { AfterViewInit, Component, TemplateRef, ViewChild } from "@angular/core";
import { IgxValueBrushScaleComponent } from 'igniteui-angular-charts';
import { IgxShapeDataSource } from 'igniteui-angular-core';
import { IgxGeographicContourLineSeriesComponent } from 'igniteui-angular-maps';
import { IgxGeographicMapComponent } from 'igniteui-angular-maps';

@Component({
  selector: "app-map-geographic-scatter-contour-series",
  styleUrls: ["./map-geographic-scatter-contour-series.component.scss"],
  templateUrl: "./map-geographic-scatter-contour-series.component.html"
})

export class MapTypeScatterContourSeriesComponent implements AfterViewInit {

    @ViewChild ("map")
    public map: IgxGeographicMapComponent;

    @ViewChild ("template")
    public tooltip: TemplateRef<object>;
    constructor() {
    }

    public ngAfterViewInit(): void {
        const sds = new IgxShapeDataSource();
        sds.shapefileSource = "assets/Shapes/WorldTemperatures.shp";
        sds.databaseSource  = "assets/Shapes/WorldTemperatures.dbf";
        sds.dataBind();
        sds.importCompleted.subscribe(() => this.onDataLoaded(sds, ""));
    }

    public onDataLoaded(sds: IgxShapeDataSource, e: any) {
        const shapeRecords = sds.getPointData();

        const contourPoints: any[] = [];
        for (const record of shapeRecords) {
            const temp = record.fieldValues.Contour;
            // using only major contours (every 10th degrees Celsius)
            if (temp % 10 === 0 && temp >= 0) {
                for (const shapes of record.points) {
                     for (let i = 0; i < shapes.length; i++) {
                        if (i % 5 === 0) {
                            const p = shapes[i];
                            const item = { lon: p.x, lat: p.y, value: temp};
                            contourPoints.push(item);
                        }
                     }
                }
            }
        }

        this.createContourSeries(contourPoints);
    }

    public createContourSeries(data: any[]) {
        const brushes = [
            "rgba(32, 146, 252, 0.5)", // semi-transparent blue
            "rgba(14, 194, 14, 0.5)",  // semi-transparent green
            "rgba(252, 120, 32, 0.5)", // semi-transparent orange
            "rgba(252, 32, 32, 0.5)"  // semi-transparent red
        ];

        const brushScale = new IgxValueBrushScaleComponent();
        brushScale.brushes = brushes;
        brushScale.minimumValue = 0;
        brushScale.maximumValue = 30;

        const contourSeries = new IgxGeographicContourLineSeriesComponent();
        contourSeries.dataSource = data;
        contourSeries.longitudeMemberPath = "lon";
        contourSeries.latitudeMemberPath = "lat";
        contourSeries.valueMemberPath = "value";
        contourSeries.fillScale = brushScale;
        contourSeries.tooltipTemplate = this.tooltip;
        contourSeries.thickness = 4;

        this.map.series.add(contourSeries);
    }
}

    API References