Fundamentals of displaying surfaces in 3D

ArcGIS 3D Analyst and ArcMap give you a variety of ways to symbolize and display rasters and surfaces. Because of the differences between rasters, TINs, and terrains, you have different options for symbolizing them.

Continuous rasters, also known as surface data, can be stretched to improve contrast. Categorical rasters, or discontinuous data, such as a lake because of its definable boundary with the surrounding landscape, can be symbolized using their unique values. Multiband rasters, such as satellite images and some aerial photographs, can be displayed as a red, green, and blue (RGB) composite or as a single stretched image. Feature data can be dynamically displayed as a raster. You can render cells with no data and background cells in different ways.

ArcScene and ArcMap allow you to symbolize TIN surfaces using the elevation values or the aspect or slope of each TIN facet. You can also show the nodes and edges of the TIN in several different ways. TINs cannot be displayed as visual layers in ArcGlobe.

Terrains can only be dynamically displayed in ArcMap and ArcGlobe.

All displayed raster and surface layers must have their base heights defined within the 3D view. Surface layers can reference themselves or other surface data to get this information. Discontinuous raster data must refer to separate elevation data or use a constant value or expression to define its z-values. In ArcGlobe, the globe's surface is described by the layers in the Elevation category.

Examples of continuous data include the following:

• Elevation data
• Temperature data
• Fire risk data

Examples of discontinuous data include the following:

• Thematic land-use data
• Rasterized feature data
• Remotely sensed image data
• Scanned maps

You can make all surfaces transparent and add depth and realism to a surface by shading it based on its position relative to a light source. You can manipulate the appearance of the surface by setting the base resolution and z-unit conversion factor.

Displaying raster surfaces in 3D

Layer properties help to define how your raster surface will display in 3D. Access the Layer Properties dialog box by right-clicking the layer in the table of contents and clicking Properties.

Raster data can be either continuous or discontinuous. Continuous raster data represents a surface. This surface may be a traditional elevation surface, or it may represent an analysis surface, such as the relative fire risk for a region. Discontinuous raster data, on the other hand, represents discrete blocks of information, such as an aerial photograph.

All supported raster data formats can be displayed in ArcGlobe as floating or draped layers. Only a continuous, single-band raster can be used as an elevation source for itself or other layers. It will be specifically categorized as an Elevation Layer on the Type tab in the table of contents.

When displaying rasters in 3D,you need to set the base heights for a layer by defining its 3D layer properties. In ArcGlobe, to display a raster surface with 3D elevation, the z-values will come from a provided surface. Floating layers require layer properties that directly specify their elevation source, which may be a constant value, a separate 3D surface data source, or themselves. Draped layers in ArcGlobe will automatically use any elevation layers that have been added into the 3D view.

Learn the steps to display a raster surface in ArcGlobe

There are three symbology layer options by which to symbolize rasters:

• Grouping their values into a number of classes
• Stretching the values to enhance contrast
• Assigning each unique value in the raster to a color

How you display a raster depends on the type of data that it contains and what you want to show. Some rasters have a predefined color scheme; for others, ArcGlobe will choose an appropriate display method that you can adjust as needed. You can change display colors, group data values into classes, or stretch values to increase visual contrast.

For multiband rasters, you can choose three bands to display together in an RGB composite. This drawing method often improves your ability to distinguish features in multispectral images.

For complete details on symbology options for raster layers, see Displaying rasters and Improving the display of raster data in the ArcMap Help.

Displaying terrain surfaces in 3D

A terrain dataset is a derived data source, calculated based on participating point, line, and polygon feature classes.

Terrain datasets are displayed similarly to TINs, where the symbology is made up of triangular facets and the nodes and edges that make up the triangles. The representation may also contain breaklines—lines that follow sets of edges that play important roles in defining the shape of the surface. Examples of breaklines are ridgelines, roads, or streams.

A terrain is used to describe a surface and does not necessarily have to be displayed in the 3D view. You can simply drape other data over it, such as an aerial photograph, to see the topography. However, you have the option to display the terrain as a layer in ArcGlobe or ArcMap. This may be required if you do not have other data to drape over the full extent of the terrain.

Learn more about using a terrain surface as a 3D elevation source

You can display just one type of terrain feature—for example, just the triangles—or all the terrain features. You can also symbolize each feature type using separate symbology. As terrains represent a calculated surface from other feature classes, you can also add in the raw source data as separate layers.

For steps on displaying terrain surfaces by symbolizing different features, refer to the following topics:

Displaying terrain faces by elevationDisplaying terrain faces by aspectDisplaying terrain faces by slopeDisplaying terrain faces by tag valueDisplaying terrain nodes by elevationDisplaying terrain edges grouped with a unique symbol

Displaying TIN surfaces in 3D

TINs are made up of triangular facets and the nodes and edges that make up the triangles. They may also contain breaklines—lines that follow sets of edges that play important roles in defining the shape of the surface. Examples of breaklines are ridgelines, roads, or streams.

A TIN is used to describe a surface and does not necessarily have to be displayed in the 3D view. You can simply drape other data over it, such as an aerial photograph, to see the topography. However, you have the option to display the TIN as a layer in ArcMap or ArcScene if you want to. This may be required if you do not have other data to drape over the full extent of the TIN.

You can display just one type of TIN feature—for example, just the triangles—or all the TIN features. You can also symbolize each feature type using separate symbology. TIN nodes and triangles can be tagged with integer values to allow you to store additional information about them. These integer values can be used as lookup codes—for example, to indicate the accuracy of the input feature data source or the landuse type code for areas on the surface. The codes can be derived from fields in the input feature classes. You can symbolize tagged features with unique values.

TIN layers cannot be displayed directly in ArcGlobe, although they can be used as elevation layers to help describe the surface of the globe. If you need to display a symbolized TIN as a layer in ArcGlobe, you have to convert the TIN to a raster.