3D is how we see the world. With 3D Web GIS, you bring an extra dimension into the picture. See your data in its true perspective in remarkable photorealistic detail, or use 3D symbols to communicate quantitative data in imaginative ways, creating better understanding and bringing visual insight to tricky problems.
Throughout history, geographic information has been authored and presented in the form of two-dimensional maps on the best available flat surface of the era—scrawled in the dirt, on animal skins and cave walls, hand-drawn on parchment, then onto mechanically printed paper, and finally onto computer screens in all their current shapes and sizes. Regardless of the delivery system, the result has been a consistently flat representation of the world. These 2D maps were (and still are) quite useful for many purposes, such as finding your way in an unfamiliar city or determining legal boundaries, but they’re restricted by their top-down view of the world.
Three-dimensional depictions of geographic data have been around for centuries. Artistic bird’s-eye views found popularity as a way to map cities and small-extent landscapes that regular people could intuitively understand. But because these were static and could not be used directly for measurement or analysis, they were often considered mere confections, or novelties, by serious cartographers, not a means of delivering authoritative content.
However, this is no longer the case since ArcGIS introduced the concept of a “scene,” which is actually more than just a 3D map. In a scene, you can also control things like lighting, camera tilt, and angle of view. The mapmaker can craft a scene that creates a highly realistic representation of geographic information in three dimensions, which provides an entirely new way for the audience to interact with geographic content. Spatial information that is inherently 3D, such as the topography of the landscape, the built world, and even subsurface geology, can now be displayed not only intuitively and visually but also quantifiably and measurably, so that we can do real analysis and hard science using 3D data.
The most obvious advantage of a scene is its ability to incorporate vertical (and thus volumetric) information—the surface elevation of mountains, the surrounding landscape, the shapes of buildings, or the flight paths of jetliners. It’s the power of the Z.
In 3D, the extra dimension enables you to include more readily recognized symbols to make your maps more intuitive. You are able to see all the “data” from all viewpoints in situ. Every symbol that you recognize on a map saves you the effort of referring to the legend to make sure you understand what it shows.
Many of man’s earliest maps, particularly of cities and smaller human habitations, were portrayed as scenes. These stylized maps were created as static 3D bird’s-eye views and were successful in providing understanding of a place. Today’s GIS authors interact with and see these scenes from many perspectives.
For most of our living moments, we experience the world within a few feet of the ground. 3D allows us to replicate this view. With data presented from this approachable perspective, the size and relative positions of objects are intuitively understood as you wander virtually through the scene. There’s no need to explain that you’re in a forest or that a lake is blocking your route—the 3D perspective immediately makes the features recognizable.
GIS content can be displayed in 2D or 3D views. There are a lot of similarities between the two modes. For example, both can contain GIS layers, both have spatial references, and both support GIS operations such as selection, analysis, and editing.
However, there are also many differences. At the layer level, telephone poles might be shown in a 2D map as brown circles, while the same content in a 3D scene could be shown as volumetric models—complete with cross members and even wires—that have been sized and rotated into place. At the scene level, there are properties that wouldn’t make sense in a 2D map, such as the need for a ground surface mesh, the existence of an illumination source, and atmospheric effects such as fog.
In ArcGIS, we refer to 2D views as “maps” and 3D views as “scenes.”
3D content can be displayed within two different scene environments—a global world and a local (or plane) world. Global views are currently the more prevalent view type, where 3D content is displayed in a global coordinate system shown in the form of a sphere. A global canvas is well suited for data that extends across large distances and where curvature of the earth must be accounted for: for example, global airline traffic paths or shipping lanes.
Local views are like self-contained fish bowls, where scenes have a fixed extent in an enclosed space. They are better suited for small-extent data, such as a college campus or a mine site, and bring the additional benefit of supporting display in projected coordinate systems. Local views can also be effective for scientific data display, where the relative size of features is a more important display requirement than the physical location of the content on a spheroid.
A “surface” is like a piece of skin pulled tight against the earth. Surface data by definition includes an x-, y-, and z-value for any point. A surface can represent a physical thing that exists in the real world, such as a mountain range, or it can be an imagined surface that might exist in the future, such as a road grading plan. It can even show a theme that only exists conceptually, such as a population density surface. Surfaces come in a wide variety of accuracies, ranging anywhere from high-resolution, 1-inch accuracy all the way down to a low-resolution surface with 90 meters or coarser accuracy.
Surfaces are fundamental building blocks for nearly every scene you will create because they provide a foundation for draping other content. Sometimes the surface itself is the star of the show (like a scene of Mount Everest). Other times the surface serves a more humble role of accommodating other crucial scene data, such as aerial imagery or administrative boundaries. And surfaces can also provide base-height information for 3D vector symbols, such as trees, buildings, and fire hydrants, for which their vertical position within the scene might not otherwise be known.
Symbolizing features using a real-world size is extremely common in 3D. For example, it’s expected that buildings, trees, and light poles all be displayed at the same relative size in the virtual world as they exist in reality. Even some thematic symbols, such as a sphere showing the estimated illumination distance of one of the light poles, will help communicate the notion of real-world size.
However, it is also useful to have symbols in the scene that are an on-screen size instead. That is, as you zoom in and out of the scene, the symbol always displays with the same number of pixels on the screen. This effect is analogous to a 2D map layer whose symbol sizes do not change as you move between map scales.
3D data is increasingly available from a wide variety of different sources. The examples featured here hint at the possibilities. Take some time to click through these apps on your computer. These and many other innovative examples are collected in the ArcGIS Web Scenes gallery.
Light detection and ranging (lidar) is an optical remote-sensing technique that uses laser light to densely sample the surface of the earth, producing highly accurate x, y, and z measurements. Lidar, primarily used in airborne laser mapping applications, is emerging as a cost-effective alternative to traditional surveying techniques such as photogrammetry. Lidar produces mass point cloud datasets that can be managed, visualized, analyzed, and shared using ArcGIS.
Integrated mesh data is typically captured by an automated process for constructing 3D objects from large sets of overlapping imagery. The result integrates the original input image information as a textured mesh using a triangular interlaced structure. An integrated mesh can represent built and natural 3D features, such as building walls, trees, valleys, and cliffs, with realistic textures and includes elevation information. Integrated mesh scene layers are generally created for citywide 3D mapping and can be created using Drone2Map™ for ArcGIS®, which can then be shared to ArcGIS Desktop or web apps.
In the past few years, drones have become an increasingly common way to capture high-resolution imagery of local areas. Drone images are generally tagged with geographic information that describes where each image was taken, making them ready for use in ArcGIS. Drone2Map for ArcGIS not only allows you to view raw drone images on a map, but you can also create both 2D maps and 3D scenes from the images.
By default, navigation below ground is disabled to avoid accidentally zooming under the ground surface of a 3D scene and becoming disoriented. If, however, your scene contains data that correctly belongs underground—such as subsurface utility pipes or geological bodies—you can enable this capability for the 3D scene.
Photorealistic views are essentially attempts to re-create reality by using photos to texture your features. These are by far the most common type of scene, with enormous amounts of effort put into making the virtual world look exactly as if you were there in person. Authors of this content create virtual worlds for simulation, for planning and design, and for promotional videos and movies. The specification remains very simple: look out the window, and make the virtual world appear like that.
In a GIS context, photorealistic views are extremely well suited for showing the public how a place has changed, or is expected to change, through time. That could mean what the cityscape will look like after a proposed building is constructed, or what a region looked like when dinosaurs roamed the earth. A photorealistic view takes the onus off users of imagining what the state of the world would look like, and simply shows them.
Using 3D elements to represent data and other nonphotorealistic information is the next frontier. The idea is to take 2D thematic mapping techniques and move them into 3D. These maps are powerful, eye-catching, and immersive information products, often viewed as navigable scenes or packaged as video to control the user’s experience and deliver maximum impact.
A 3D scene quickly starts to feel like virtual reality when photorealistic and thematic techniques are used in combination. The photorealistic parts of the scene provide a sense of familiarity to the user, and the thematic parts can convey key information. Slip on an Oculus Rift headset, and you’re suddenly immersed in a 3D world.
We experience and see spaces in 3D. People viewing the content are, effectively, invited to imagine themselves within the scene as they move around. This means that the styling, or the look, of the world surrounding them can have a strong impact on how they feel about the scene in general.
For example, a city shown with dark lighting and heavy fog lends a sense of foreboding or decay, while a bright and sunny depiction of the same city, with people and cars, implies that the city is vibrant and safe—think Gotham versus Pleasantville.
The styling of the GIS content itself within the 3D scene also has a big impact on the look and feel of the scene. There are basically three choices available: fully photorealistic, fully thematic, or a combination of photorealistic and thematic.
Thematic views model and classify reality in a way that communicates spatial information more effectively. Thematic 3D views use common 2D cartographic techniques, such as classifications, color schemes, and relative symbol size, to simplify the real world into something that can be more readily understood. 3D scene authors create schematic, simplified representations to more effectively convey some key piece of information, particularly for scientific visualization.
For GIS users, thematic content can be an effective, and eye-catching, way to display more than just where something is—it can also show key properties about that thing. As in the example below, typhoon data points can be symbolized to show both the path of the storm and its changing wind speed.
When people talk about seeing an amazing computer-generated 3D view, they are nearly always talking about a realistically rendered view. You know, the one with ray-tracing and ambient lighting and reflective surfaces, where it looks so much like the actual world you can almost touch it. Although this type of view is useful for conveying certain types of geographic information—such as a proposed future cityscape—it is not the right way to render everything. That is, in the same way that every map is not an aerial image, every 3D view should not be an attempt to re-create the real world.
GIS users share maps and scenes with one common goal—to communicate spatial information—and careful use of thematic symbols in 3D can be as effective, or even more effective, than similar techniques in 2D. For example, showing tree features as colored spheres on sticks (with red representing those that need to be trimmed) is much more to the point than displaying those same trees as highly realistic models covered with leaves and branches. The size of the spheres can still contain elements of the real world, such as the height and crown width of each tree, but the real value of the symbols comes from their cartographic display—a simpler, more representative display that provides an immediate visual understanding of which trees are important. The advantage of using 3D is that a sphere on a stick still looks enough like a tree that you don’t need to have an explicit legend saying Tree.
For centuries, cartographers have been limited to two dimensions. They’ve experimented with more effective ways of communicating spatial information through the clever use of symbols and classifications and colors. The existence of medieval, bird’s-eye view maps shows that many grasped the power of the third dimension even if they didn’t have the tools to fully explore it. But now suddenly, everyone has these tools, and 3D cartographers have the extra, wonderful third dimension to work with.
3D mapping and cartography have applications across a broad swath of industries and in government and academia. The examples featured here hint at the possibilities.
Take some time to click through these apps on your computer. These and many other innovative examples are collected in the ArcGIS Web Scenes gallery.
This 3D scene of Portland, Oregon, was created to show the impact of sunlight and visibility for a proposed high-rise development downtown.
The mapping of building interiors as well as exteriors is an informative and immersive way to navigate campuses, museums, sports stadiums, and other public venues.
Massive datasets, such as three years’ worth of crimes committed in Chicago, lend themselves to 3D visualization. In this case, the z-axis is actually used to depict time.
The basic ArcGIS scene viewer allows you to work immediately in 3D space. It functions with desktop web browsers that support WebGL, a web technology standard built into most modern browsers for rendering 3D graphics. Check out this gallery of scenes to verify that your browser is properly configured.
This interactive globe lets you explore the world. Quickly display 3D and 2D map data, including KML, and sketch placemarks to easily understand spatial information. Download it here.
ArcGIS Pro is a modern 64-bit desktop application that has extensive 3D capabilities built in. You can work with 2D views and 3D scenes side by side. ArcGIS Pro is included in the Learn ArcGIS experience.
CityEngine is an advanced tool for scenario-driven city design and developing rules for creating procedurally built cityscapes.
Each scene starts with a basemap draped on the 3D elevation surface of the world. Zoom to your area of interest and begin to add your operational overlays.
Before you start designing your new scene, you need to know its purpose. What is the message or information you intend to convey?
The answer to that question will help you design many elements of your scene.
The key point is that each of your decisions should be rooted in why you are building the scene in the first place.
The beaches and inlets along the coast of Palm Beach County, Florida, contain a delicate ecosystem teeming with flora and fauna. However, beaches are unstable by nature. Beach sand is washed away by ebbing tides and occasional storms. Coastal areas require frequent restoration and maintenance. Sand is excavated, or dredged, from shallow areas or inlets to replenish eroded beaches, while artificial reefs are constructed to protect the shoreline. To manage these complex restoration efforts, proper monitoring and mapping is essential.
In these lessons, you’ll help the Palm Beach County beach restoration efforts by mapping some of the county’s major beaches and inlets as part of a presentation for both the public and policy makers. To emphasize bathymetric features and topography, you’ll create your map in 3D using the ArcGIS scene viewer. Begin by adding layers depicting reefs, sediment, and dredging areas to a new scene. Then capture slides of key areas so that users can quickly navigate to the locations you want to emphasize. Finally, create a web app to share with others.