Visualize map image layers—ArcGIS Velocity

ArcGIS Velocity includes an interface to explore dynamic aggregation visualizations and save desired visualization and symbology settings for map image layers. These visualizations are useful to control dynamic aggregation visualization settings in map image layers in order to effectively visualize large volumes of data.

Data stored by Velocity is backed by a spatiotemporal big data store, therefore data is indexed and aggregations are available.

Consider an analytic that creates an output layer using the Feature Layer (new) output and captures vehicle location observations from connected cars. The resulting feature layer would likely contain millions of records over time or more. In a web map, rendering millions of feature points is not an effective visualization strategy. Instead, you can use the map image layer that is created with every feature layer generated by Velocity. These map image layers allow dynamic aggregation visualization options to render geohash, square, hexagon, or triangle bins representing a count of features within each bin. Alternatively, you can symbolize each bin with a summary statistic on an attribute field of the data to represent the nature of features within each bin.

Using the map image layer editing interface, you can explore different aggregation and statistic settings, bin styles, feature styles, and label styles. Once satisfied with the configuration, the settings can be saved so that any user who consumes the map image layer will see the selected dynamic aggregation visualization.

Edit map image layer

Follow the steps below to edit a map image layer's rendering.

In the Velocity application, click Layers from the menu on the left.
Locate the desired map image layer and click the Edit pencil icon.
Edit the map image layer rendering as appropriate.

Aggregation settings

The parameters on the Aggregation Settings pane control the general settings for feature aggregation, specifically what is represented by the aggregation (raw feature count or a feature statistic), the style of aggregation, the feature threshold, and bin size.


Parameter	Explanation
Statistics Field	Specifies the field to use for statistic calculation. If None is selected, the feature aggregation value will represent a count of features within each bin. If a statistics field is selected, the statistics type, selected in the next parameter, will be applied to the values of the statistic field for features that fall within the each bin. The feature aggregation bin will then be styled according to the resulting value. For example, if the statistic field chosen was Vehicle_Speed, and the statistic type chosen was Average, then each dynamic feature aggregation bin would show the average speed of all the vehicle observations within that bin.
Statistics Type	Specifies the type of statistic to apply to the values in the selected statistic field. This parameter is only shown if a statistics field is selected. For example, if the statistic field selected is Vehicle_Speed, and the statistic type chosen was Average, then each dynamic feature aggregation bin would show the average speed of all the vehicle observations within that bin. Different statistics are available for different field types including: Integer field: Average Minimum Maximum Standard deviation Sum Variance Count distinct Count Float field: Average Minimum Maximum Standard deviation Sum Variance Count distinct Count String field: Count Count distinct Date field: Count Count distinct
Aggregation Style	The desired aggregation style. This represents the bin shape of the dynamic aggregation. Options include: Geohash Square Pointed hexagon Flat hexagon Pointed triangle Note: Only aggregation styles specified when configuring the Feature Layer (new) output in the analytic will be available in the drop-down.
Feature Threshold	Specifies when to switch the rendering style of the map service between aggregation and discrete features. The default is 2000. When the number of features in the current map extent is more than the feature threshold specified, the layer will be rendered using an aggregation style; if equal or less, the layer will be rendered showing raw features. If set to0, the layer will always render using aggregation.
Bin Size	Specifies the size of the bins. Options include: Small Medium Large

Bin styles

The parameters on the Bin Styles pane control the style options for the fill color, outline color, and outline size for each dynamic aggregation bin. These parameters use the bin value as a weight to interpolate from the min to the max of the range values specified.

A bin with a bin value equal to the min of the range value uses the min of the fill style, outline style, and outline width specified. A bin with the bin value equal to the max of the range value will use the max of the fill style, outline style, and outline width specified.
If a bin value falls between the min and the max range value, the aggregation renderer uses its bin value as a weight to interpolate from the min to the max of range values to determine the fill style, outline style, and outline width for the bin.
If a bin value falls outside of the range values, the aggregation renderer will use the min value if its bin value is smaller than the min range value and use the max value if its bin value is greater than the max range value.
If leaving min and max range values blank, the aggregation renderer will calculate the min and max bin values from the current map extent and use them as the min and max for the range values.


Parameter	Explanation
Fill Style	The minimum and maximum fill colors. If a bin value falls between the min and the max range value, the aggregation renderer uses its bin value as a weight to interpolate from the min to the max of range values to determine the fill style for the bin.
Outline Style	The minimum and maximum outline colors. If a bin value falls between the min and the max range value, the aggregation renderer uses its bin value as a weight to interpolate from the min to the max of range values to determine the outline style for the bin.
Outline Width	The minimum and maximum outline width. If a bin value falls between the min and the max range value, the aggregation renderer uses its bin value as a weight to interpolate from the min to the max of range values to determine the outline width for the bin.
Range	The range of values to which rendering will apply varying fill styles, outline styles, and outline widths. If a bin value falls outside of the range values, the aggregation renderer uses the min value if its bin value is smaller than the min range value and use the max value if its bin value is greater than the max range value. If leaving min and max range values blank, the aggregation renderer will calculate the min and max bin values from the current map extent and use them as the min and max for the range values.
Normalize By Bin Area	Bins that appear the same size on a map can cover a different geographically sized area. For example, a bin at the equator covers a larger geographic area than a bin at the north pole even if the two bins are the same size in a map. If their bin values are the same, the bin at the equator has less density compared with the bin at the north pole. When Normalize By Bin Area is checked, the rendering is normalized. For example, for two bins with the same value, the bin at the equator will have a lighter color, while the bin at the north pole will have a darker color, assuming the fill color the max value uses is a darker color than the min value. When Normalize By Bin Area is unchecked, the renderer treats all bins as the same sized geographic area.

Feature settings

The parameters on the Feature Settings pane controls how raw features will be rendered. Individual features are only rendered when the number of features to be rendered in the current map extent is less than the feature threshold specified. The raw feature rendering of the map image layer is limited to simple vector symbols (circles, squares, diamonds, pointers, etc). Raw features can be rendered using a Simple renderer or Class breaks renderer.

Simple

Raw features can be rendered using a Simple renderer. The Simple renderer renders all features in a feature layer with one symbol.


Parameter	Explanation
Renderer	Specifies the renderer type. Options include simple, class breaks, or unique value renderer.
Symbol Style	The symbol style to render features. Options include circle, square, diamond, triangle, cross, X, pointer.
Feature Size	The size of the feature.
Feature Color	The color of the feature.
Outline Color	The color of the outline.
Outline Width	The width of the outline.
Feature rotation	Whether or not to rotate features.
Rotation type	The rotation type used to rotate the simple marker symbols. The rotation type chosen controls the origin and direction of rotation. If the rotation type is defined as Arithmetic, the symbol is rotated from east in a counter-clockwise direction where east is the 0° axis. If the rotation type is defined as Geographic, the symbol is rotated from north in a clockwise direction where north is the 0° axis. Arithmetic—0° is east and advances counter-clockwise. Geographic—0° is north and advances clockwise.
Rotation field	The field containing the values to be used for rotation.
Rotation angle	Adjusts the angle of all features relative to the screen in degrees.

Class breaks

Raw features can be rendered using a Class breaks renderer. The Class breaks renderer defines the symbol for each feature in a feature layer based on the value of a numeric attribute. The numeric attribute values are used to define data ranges for the classes. Each feature is assigned a symbol based on the class break of its numeric attribute value.


Parameter	Explanation
Renderer	Specifies the renderer type. Options include simple, class breaks, or unique value renderer.
Classify data	Specifies the classification method. Options include manual breaks, natural breaks, equal interval, standard deviation, and quantile.
Class breaks field	Specifies the field used for calculating class break values.
Color Ramp	Applies a range of colors to the classes. Choose one of many available color ramps, or apply a unique color ramp using the fill style of your bins.
Class Count	Defines the total number of classes. The classes can be manually adjusted in the class breaks histogram.
Class Settings	Defines the fill and outline settings for a respective class. Access the class settings by selecting a class break value.
Symbol Style	The symbol style to render all features. Options include circle, square, diamond, triangle, cross, X, pointer.
Feature Size	The size of all features.
Outline Color	The color of all feature outlines.
Outline Width	The width of all feature outlines.
Feature rotation	Whether or not to rotate features.
Rotation type	The rotation type used to rotate the simple marker symbols. The rotation type chosen controls the origin and direction of rotation. If the rotation type is defined as Arithmetic, the symbol is rotated from east in a counter-clockwise direction where east is the 0° axis. If the rotation type is defined as Geographic, the symbol is rotated from north in a clockwise direction where north is the 0° axis. Arithmetic—0° is east and advances counter-clockwise. Geographic—0° is north and advances clockwise.
Rotation field	The field containing the values to be used for rotation.
Rotation angle	Adjusts the angle of all features relative to the screen in degrees.

Unique value

Raw features can be rendered using a Unique value renderer. The Unique value renderer renders all features in a feature layer based on one or more matching attributes.


Parameter	Explanation
Renderer	Specifies the renderer type. Options include simple, class breaks, or unique value renderer.
Unique value field	Specifies the field used for determining unique values.
Manage Values	Defines what is a unique value to symbolize. Values not present in the current data set can be manually added.
Color Ramp	Applies a range of colors to the unique values.
Unique Value Settings	Defines the fill and outline settings for a single unique value. Access the unique value settings by selecting a unique value category.
Symbol Style	The symbol style to render all features. Options include circle, square, diamond, triangle, cross, X, pointer.
Feature Size	The size of all features.
Outline Color	The color of all feature outlines.
Outline Width	The width of all feature outlines.
Feature rotation	Whether or not to rotate features.
Rotation type	The rotation type used to rotate the simple marker symbols. The rotation type chosen controls the origin and direction of rotation. If the rotation type is defined as Arithmetic, the symbol is rotated from east in a counter-clockwise direction where east is the 0° axis. If the rotation type is defined as Geographic, the symbol is rotated from north in a clockwise direction where north is the 0° axis. Arithmetic—0° is east and advances counter-clockwise. Geographic—0° is north and advances clockwise.
Rotation field	The field containing the values to be used for rotation.
Rotation angle	Adjusts the angle of all features relative to the screen in degrees.

Label styles

The parameters on the Label Styles pane control how aggregation bins will be labeled. Parameters available include whether or not to show labels, desired font, label size and color, label style, and label format.


Parameter	Explanation
Show labels	Specifies whether or not to show labels on the aggregations.
Font	The font to be used for labels.
Size	The size of the labels.
Color	The color of the labels.
Style	The style of the labels. Options include: Plain Bold Italic Bold and italic
Format	The format to use for labels. This is a text value format pattern based on the Java Decimal Format specification. See label format parameter examples in the below table.

Label format parameter examples:


Raw value	Label format pattern	Resulting Label	Explanation
123456.789	###,###.###	123,456.789	The pound sign (#) denotes a digit, the comma is a placeholder for the grouping separator, and the period is a placeholder for the decimal separator.
123456.789	###.##	123456.79	The value has three digits to the right of the decimal point, but the pattern has only two. The format method handles this by rounding up.
123.78	000000.000	000123.780	The pattern specifies leading and trailing zeros, because the 0 character is used instead of the pound sign (#).
12345.67	$###,###.###	$12,345.67	The first character in the pattern is the dollar sign ($). Note that it immediately precedes the leftmost digit in the formatted resulting label.
789,123,456,789	###.##KMB	789.12B	The KMB characters indicate to represents billions with a B and round to the digits specified by the pound signs (#).
789,123,456	###.#kMG or ###.##KMB	789.1M	The kMG or KMB characters indicate to represents millions with an M and round to the digits specified by the pound signs (#).

Save changes

Optionally, you can choose to save the settings and changes you made in the interface. If the Save layer button is pressed, when client applications such as ArcGIS Online web maps consume the map image layer, it will be symbolized and rendered according to the dynamic aggregation and feature rendering settings defined.

For example, consider the illustration below which shows a web map in which aggregation and label settings were modified.

Modified aggregation settings and labels viewed in a web map

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