Analyze Data Coverage

The Data Inspector Library allows you to assess the coverage of your datasets stored in the HERE platform across partitions both on global and local scales. You can see where your partitions are located on a map and figure out the geographical distribution with these maps:

  • Data coverage map: Reflects the geographical availability of partitions. The coverage map is always rendered as an overlay on top of the base map for all HERE-Tiled versioned and volatile data layers.

    Coverage map
    Figure 1. Coverage map
  • Data size heat map: Represents the size of data contained in every tile with related color gradients. This map is available for HERE-Tiled versioned layers only.

    Data size heat map
    Figure 2. Data size heat map
  • Data freshness heat map: Represents the time when the data in a partition was last updated (tile age) and allows you to get a quick sense of the freshness of a dataset across partitions. This map is available for HERE-Tiled versioned layers only.

    Data freshness heat map
    Figure 3. Data freshness heat map

Heat maps are rendered as an overlay on top of the coverage map.

How To Use

You can analyze the coverage of your datasets through the HERE platform portal. For this, browse to the catalog layer you need and select the Inspect tab. Then, in the upper-left corner of the Data Inspector, click the Control Panel button to display the Heat map panel. For more details on the coverage rendering rules, see the chapters below.

You can also embed coverage with data size and freshness heat maps in your Data Inspector Library-based applications. For this, use the CoverageControls component in combination with the CoverageDataSource with the AggregatedCoverage mixin applied, as in the example below:

const coverageClass = AggregatedCoverage(CoverageDataSource);
const coverageDataSource = new coverageClass(config);

To use this feature with the DataInspector class, enable two of the options below:

enableCoverage: true,
enableExtendedCoverage: true,

To see how the coverage maps work, go to the Data Inspector Library examples.

Coverage Rendering Rules

The way coverage data, tile age data, and tile size data are visualized at a certain map zoom level depends on a layer’s data level.

To learn the level at which data is stored in a layer, do either of the following:

  • In the Data Inspector's Control Panel, view Data level.
  • In the HERE platform portal, go to the layer’s details page and consult the layer’s Zoom Levels property.
  • In the OLP CLI for the HERE platform, run the command olp catalog layer show <catalog HRN> <layer ID> [command options] chapter of the Command Line Interface Developer Guide.

Rule for Data Level - 3 Range

For the Data Level – 3 range (inclusively), the most up-to-date, non-aggregated coverage data are shown. For example, the data level of the Building Footprints layer in the HERE Map Content catalog is 12. You can zoom out up to the level 9 and still be able to view the freshest tile coverage, tile size, and tile age data.

The coverage map, in this case, is rendered as a grid with explicit tile borders.

To enable heat maps, in the Heat map panel, click the eye button. To switch between the data freshness and tile size heat maps, under Type, select Size or Freshness.

For the Data Level - 3 range, all the controls in the Heat map panel are enabled (see the chapters below).

Color Scale

The color scale shows a palette of color gradients that represent various tile sizes or tile age on the heat map. By default, the age and size values are aggregated on a global scale.

Size values at the top of the color scale show the smallest and the largest partitions in the entire layer. For example, in the image below, the smallest partition in the layer has 315 bytes of size and the largest one - 286.73 MB.

Global tile sizes
Figure 4. Global tile sizes

Age values at the top of the color scale show the "oldest" and the "youngest" partitions in the entire layer. For example, in the image below, the "oldest" partition in the layer was updated 3 years ago while the "youngest" one - just an hour ago.

Global tile age
Figure 5. Global tile age

Show Local Maxima

This check box allows you to change the scale of heat maps from global to local.

On the local scale, sizes at the top of the color scale indicate the smallest and the largest partitions that are currently visible in the Map View. For example, in the image below, the smallest partition in the Map View has 31.93 KB and the largest one - 46.44 MB.

Local tile sizes
Figure 6. Local tile sizes

On the local scale, age values at the top of the color scale indicate the "oldest" and the "youngest" partitions that are currently visible in the Map View. For example, in the image below, the "oldest" tile in the Map View was updated 2 years ago while the "youngest" one - 3 days ago.

Local tile age
Figure 7. Local tile age

Opacity

The Opacity slider allows configuring the opacity of the heat map overlays in relation to the base map.

Rule for Data Level + 4 & up Range

For the Data Level + 4 & up range, the coverage, age, and size data are aggregated from the underlying partitions. In this mode, the aggregated data is precalculated on a daily basis for each HERE-Tiled layer. For volatile layers, only coverage data is precalculated.

Therefore, the coverage data shown on these higher zoom levels is at least 24 hours outdated. For more information on the HERE-Tiled partitioning schema, see the Partitions chapter of the Data API Developer Guide.

Now let's go back to our Building Footprints layer example in the chapter above. If you zoom out this layer to the 5th level and up, you can view slightly outdated, approximate coverage, age, and size data.

The coverage map, in this case, is rendered as a grid with implicit tile borders and shows aggregated data coverage. If at least one of the underlying child partitions contains data, aggregated rectangles on the coverage overlay are rendered.

If you click the eye button, heat maps are shown as a color map for aggregated tile data. The aggregation mechanism sums the sizes and ages of all underlying child tiles and renders aggregated rectangles on the corresponding heat map.

For the Data Level + 4 & up range, the color scale always represents the global scale, and, therefore, the Show local maxima checkbox is disabled.

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