TIN symbology

Elevation, slope, and aspect are built into the structure of a TIN. Because of this, you can quickly change the symbology of TIN faces to show slope, aspect, or elevation.

The same TIN symbolized by elevation, slope, and aspect.

How are slope and aspect measured on a TIN?

On a TIN, both slope and aspect are measured in degrees. Slope values range between 0 and 90 degrees, where 0 indicates no slope. Aspect is also measured in degrees. North is 0 degrees, east is 90 degrees, south is 180 degrees, west is 270 degrees, and –1 is the aspect value for flat slopes.

Or, you can use the fill patterns of your choice to symbolize a TIN.

Picture fills can add a touch of reality to your TIN. In this case, the top graphic shows a TIN with its default elevation symbology; the lower graphic shows the same TIN symbolized with picture fills.

You can draw a TIN showing just its edges, nodes, or faces. You can also create a combination of these features, showing nodes, a specific edge type, and faces all on the same TIN, for example. You can symbolize the TIN by elevation, with a single symbol, or based on a color scheme of your liking.

What types of edges do TINs have?

There are four different types of edges associated with TINs.

Hard edges are line or polygon boundaries that were incorporated into the TIN during its creation. Hard edges typically represent a line that defines a sharp break in slope.

Hard edges define a sharp break in elevation or slope. In this TIN, the hard edges are drawn in red and represent the surface elevation of a river.

Soft edges represent line or polygon boundaries that were incorporated into the TIN during its creation and do not represent a sharp break in slope.

In this TIN, the soft edges are shown in yellow and represent the study area boundary.

Outside edges are made when you create a TIN in combination with a clip polygon. Input points not overlapped by the clip polygon are still interpolated, but as outside edges. (For now, think of a clip polygon as a layer that defines the spatial extent of your analysis. You will learn about clip polygons in the next module.)

In this TIN, the outside edges (shown in white) represent the areas that were located outside the clip polygon's extent.

Regular edges represent all TIN edges other than the hard, soft, or outside edges.

In this graphic, the regular edges are shown in pink.

Above you see the same TIN drawn four different ways: only its faces (top left), only its edges (top right), only its nodes (lower left), and with a combination of nodes, edges, and faces (lower right).

Several different TIN renderers come with 3D Analyst. A renderer is a predefined drawing style for a TIN. For example, there is a renderer for drawing TIN faces by elevation, a renderer to draw them by slope, and a renderer to draw them by aspect. Renderers let you quickly change the symbology of your TIN.

3D Analyst provides several different renderers you can use to draw your TIN. You can draw your TIN with just one renderer or use a combination of two or more.