Interactive tools for terrain datasets
In ArcMap, all of the interactive tools on the 3D Analyst toolbar work on terrain datasets:
- Create Contours
- Create Steepest Path
- Create Line Of Sight
- Interpolate Point, Line, And Polygon
- Create Profile Graph
The tools work basically the same with terrains as with rasters and TINs, but there's a difference in behavior that is tied to display scale and terrain pyramids. The first thing you'll notice is that the tools are not always enabled when a terrain is active. This is because terrains have pyramids that can optionally be used in analysis. By default, analysis on lower level-of-detail (LOD) pyramids is turned off, and the tools will only be enabled when the terrain is displayed at full resolution. This means you might need to zoom in on the display before the tools become available for use.
For some applications, the full-resolution data is oversampled and redundant. It's also possible that the level of accuracy associated with the full-resolution data is not required. For this, you can be more liberal about enabling the tools. You can use them at smaller display scales and improve interactivity because a smaller, generalized version of the terrain is required.
To enable the tools at lower LODs, go to the terrain layer Properties dialog box and click the Analysis tab. Here you can indicate at which pyramid level you want the tools enabled. By default, it's 0, the full-resolution data. If you switch to pyramid level 2, which may have a reference scale of 1:10,000, the tools will be enabled at scales of 1:10,000 or higher. The analytic result of a tool is based on the approximate resolution of the terrain at the time the tool is used.
In addition to the 3D Analyst tools, the standard Identify tool is also supported on terrain layers and reports elevation, slope, and aspect for a query point. The values are always based on the current display resolution.