You can use representative cartographic techniques to thematically symbolize features in a scene to better communicate additional information about the geospatial features in the view. The styling can use simple techniques, like color and representative shapes, or more complex techniques, like vertical exaggeration and in-scene chart objects.
These scenes can be fully thematic, using representative shapes for all 3D objects, or they can mix thematic components with realistic elements, like buildings, aerial imagery, and trees.
Workflows
Using color
Color is often used in thematic maps to indicate either a graduated value range, such as sea surface temperature, or classifications of values, such as land-use type. Both approaches also work in 3D, and you can mix color with the use of real-world shaped objects to indicate values without losing the representation of what the object is. For example, realistic 3D bus stop models could be colorized based on the number of passengers who embark there. Note that there are many things to consider when defining colors and choosing color ramps in any cartographic product.
Some examples of using color inside a scene include:
- Highlighting trees that could be impacting power lines
- Using a color ramp to indicate per-building earthquake readiness
- Colorizing individual floors of a building by their land-use type
One thing to be aware of when working with color in 3D is that scene lighting can have a major impact on the appearance of color, so it is possible to lose clarity of the values simply based on the camera’s current viewpoint. For example, a building that is symbolized with a green color will appear darker on the shadowed side compared to the side facing the light source.
Using shape and size
The shape of a 3D symbol is not required to be physically accurate. Instead, it can be geometric, like a sphere, or representative, like the letter. For example, the letter I could symbolize an information booth. You can also use a simplified model, like a single generic car charging station, to show their availability and existence in the scene without modelling the precise structure and layout of every single facility.
Varying the size for 3D symbols will show a range in values for the various features. Larger objects are generally seen as more important and will draw the user’s eye. The comparison of relative sizes between objects will also indicate which of them is more significant or impactful. You can also use size purely to make an important location easily discoverable.
Some examples of using size and shape inside a scene include:
- Earthquake points with a sphere size based on the magnitude of the earthquake.
- 3D airport control tower models with sizes based on the number of daily aircraft.
- Points of interest, like the Eiffel Tower, are shown as enormous locational models.
There are a few things to be aware of when using size and shape to communicate values, including:
- The camera’s viewpoint matters, with features closer to the camera naturally appearing larger than those that are farther away.
- The volumes of objects like spheres are technically cubic, so using radius directly as the size multiplier can overly exaggerate differences in values.
- Some ArcGIS applications, like ArcGIS Pro, allow you to scale symbols in real-world size like meters, or in a scene space size, like point.
The technique used when applying size to communicate data values is known as visual variables or attribute-driven symbology, in which a field or expression is connected to a size property of the symbol, such as the vertical height of a tree model, which allows the same symbol to be a different size per feature.
Using vertical exaggeration
Vertical exaggeration is a useful technique when communicating terrain elevations and slopes. Like when the surface is either very flat or being viewed from a large distance, the height difference will be more pronounced. For example, flood risk in some areas of Florida is dependent on even a few extra feet of elevation change and applying a visual exaggeration of the surface of three or five times the height can better highlight these differences. Even in more mountainous areas, as the camera gets farther away from the ground, it can be difficult to see elevation changes that feel obvious when there in person. You can also use vertical exaggeration in a purely thematic way to, for example, show the relative sizes of the mountain ranges of earth when looking at it from space, for example.
Vertical exaggeration is directly available in ArcGIS Pro. In ArcGIS Runtime applications, vertical exaggeration can be configured in the scene’s definition. In ArcGIS Earth, which is built on Runtime technology, the property is available through a widget displayed on the view. In Scene Viewer, however, exaggeration of the ground surface can only be done by multiplying the elevation source data by the required value and publishing it as a separate elevation layer.
Using in-scene chart objects
Another option is to use shapes of different sizes—usually height—within the scene to communicate relative values. For example, the vertical size of a fixed-width column can represent properties like income or crime rates or predicted jobs. The position of each column is geolocated within the view, and can represent a point, such as an individual school, or an area, such as an entire school district. The size of each symbol communicates the value, and the position of the column can help show patterns across the region.
A rendering technique available in ArcGIS Pro that can be helpful when creating images that include in-scene chart objects is known as parallel drawing mode. This removes the distortion of perspective rendering, where near objects appear larger than far objects. It effectively makes the output image directly measurable, where the size of an object in the foreground can be directly compared to one in the distance.
A few things to be aware of when creating in-scene chart objects include:
- Extrusion of irregular shapes using an attribute value, such as extruding country boundaries by population values, is an option that can look compelling, but is not necessarily the best at giving a clear visual indication of importance. This is because large areas with medium heights will consume more display area than small areas with larger heights.
- Objects closer to the camera will appear larger in perspective view mode, making it easy to give a false impression of the data purely by the choice of the viewpoint.
- Consider including other elements in the view, such as labels or attribute-driven text symbols or a color ramp, that more explicitly state the values used for each chart object.
Explore the following resources to learn more about using attributes to set object elevation and height in ArcGIS.
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Tutorials
Guided, hands-on lessons based on real-world problems:
- Learn how to improve 3D thematic symbology
- Learn how to create thematic representations of different aspects of a city
- Visualize the expansion of public transportation
- Visualize business growth by industry
- Visualize social distancing across California
- Learn how to use urban and thematic 3D maps to plan scenarios for land use
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