Create a terrain dataset

Available with 3D Analyst license.

A terrain dataset is built from multiple data sources such as lidar mass point collections, 3D breaklines, and 3D-based survey observations. The data sources used to create terrain datasets are managed as a set of integrated feature classes in a geodatabase feature dataset. Building a terrain dataset to efficiently visualize and store a large amount of source measurements can be a lengthy process. To create larger terrains, it is recommended to build the terrain dataset in phases by appending to referenced or embedded feature classes. The primary reason is to avoid extremely long processes where everything would be lost if a system failure were to occur.

Creating a terrain dataset requires a ArcGIS 3D Analyst extension. Geoprocessing tools in the Terrain Dataset toolset are used for data automation. Run these tools in the order outlined below, ideally from a model or script, to automate the creation of a terrain dataset.

1. Import terrain dataset source measurements
2. Create Terrain
3. Add Terrain Pyramid Level
4. Add Feature Class To Terrain
5. Build Terrain

Import terrain dataset source measurements

One of the most important processes when creating a terrain dataset is to import source measurements correctly into a geodatabase feature dataset. Terrain datasets can be generated from several different types of data. Such data can include lidar and sonar points, breaklines and points derived from stereo photography, and other forms of survey data. The feature class geometry types supported for terrain datasets include points, multipoints, lines, and polygons. Source data used to generate a terrain dataset will come in either ASCII or LAS file formats.

ASCII 3D To Feature Class and LAS To Multipoint are the two geoprocessing tools offered to import terrain source data into desired feature classes. These tools are available in the 3D Analyst toolbox. Both tools can be found in the From File toolset of the 3D Analyst toolbox's Conversion toolset.

Run the Create Terrain tool

The Create Terrain tool creates a new terrain dataset in the specified feature dataset.

Note:

All feature classes participating in the terrain dataset must reside in the same feature dataset specified in the Create Terrain tool.

1. Open the Create Terrain tool.
2. Click the Input Feature Dataset button and browse to the feature dataset where the terrain dataset is to be created.
3. Select the feature dataset and click OK.
4. Type a name for the new terrain dataset in the Output Terrain parameter.
5. Type the average point spacing in the Average Point Spacing parameter.

   The Average Point Spacing value is based on the data that will be used to build the terrain dataset. This value doesn't need to be exact but should represent a good approximation. If the data was gathered at significantly different densities from one location to another, give more weight to the smaller spacing.

6. Optionally specify a Maximum Overview Size value.

   The terrain overview is the coarsest representation of the terrain dataset. The maximum size is the upper limit of the number of measurement points sampled to create the overview. The default is 50,000.

7. Set Pyramid Type to the option you want to use to create and organize the terrain data, either Window Size (the default) or Z Tolerance.
8. If Window Size is chosen, the following must also be specified:
   • Window Size Method—The default is Minimum Z.
   • Secondary Thinning Method—The default is None.
   • Secondary Thinning Threshold—The default is 1. This is optional.
9. Optionally click Environments and enter a configuration keyword (Config Keyword) for ArcSDE.

   A configuration keyword is used to indicate storage and location parameters for optimal space. It applies only to ArcSDE geodatabases and is provided by the database administrator.

10. Click Run to execute the tool.

Run the Add Terrain Pyramid Level tool

The Add Terrain Pyramid Level tool defines the pyramid levels for an existing terrain dataset.

1. Open the Add Terrain Pyramid Level tool.
2. Click the Browse button and browse to the location of the terrain dataset to which you want to add the pyramid level definition.
3. Select the terrain dataset and click OK.
4. Type the first pyramid level in the Pyramid Level Definition window (1 5000).
5. Click below the first entry to see an additional window to add a second entry. Keep adding pyramid levels until all desired pyramid levels are entered.

   Note:

   The Pyramid Level Definition window defines the z-tolerance or window size and reference scale of one or more pyramid levels that will be added to the terrain dataset. The values are given in space-delimited pairs, one pair for each level. The z-tolerance can be specified as a floating point value. The reference scale must be provided as a whole number (for example, a value of 24,000 represents a scale of 1:24,000).

6. Click Run to execute the tool.

Run the Add Feature Class To Terrain tool

The Add Feature Class To Terrain tool defines how each feature class contributes to an existing terrain dataset. Each feature class must already reside in the feature dataset along with the terrain dataset.

1. Open the Add Feature Class To Terrain tool.
2. Click the Browse button and browse to the feature dataset where the terrain dataset resides.
3. Select the terrain dataset and click OK.
4. Click the Input Features button and browse to the feature dataset where the input feature class resides.
5. Select the feature class and click OK.
6. Set the following feature class properties appropriately for the contributing feature class:
   • Input Features—The name of the input feature class that is to be added to the terrain dataset.
   • Height Field—The field supplying heights for the features. If z-values are coming from the feature geometry, the Shape field is listed.
   • Type —Defines how the feature geometry is incorporated into the triangulation for the surface.
   • Group—Groups thematically similar data, representing the same geographic features but at different levels of detail. Feature classes belonging to the same group are assigned the same group ID.
   • Min Resolution and Max Resolution—These parameters are used for feature classes added as polyline or polygon surface feature types. They define the range of pyramid levels the features will be enforced in the surface. You enter the resolution thresholds provided in the resolution of the terrain dataset's pyramid levels.
   • Overview—Indicates whether the feature class contributes measurements to the coarsest representation of the terrain dataset. The overview is what's drawn by default when zoomed to the full extent of the terrain dataset. Points are always used in the overview. The setting here is for line and polygon data sources. Only set those feature classes that must be represented in the overview to True. For example, you may not need detailed breaklines, but you may need a clip polygon, particularly if the data boundary is irregularly shaped. If you have a detailed boundary, generalize it and use the coarser representation for the overview. Use the detailed version in more detailed pyramid levels.
   • Embed—Embedded feature classes are contained by the terrain dataset. Only multipoint feature classes can be embedded.
   • Embed Name—The name of the embedded field.
   • Embed Fields—If the multipoint feature class is being embedded and has LAS (lidar) attributes created via the LAS To Multipoint import geoprocessing tool, you can preserve those attributes. Specify the LAS attributes to save with the embedded points.
   • Anchor—A point feature class can be assigned the anchored property. Anchor points remain through all pyramid levels of a terrain dataset. They are never filtered or thinned. This ensures they are present in the terrain surface regardless of the resolution pyramid level used.
7. Click the Add New button to add the feature class to the list in the tool.
8. Repeat steps 5 through 7 for each contributing feature class to continue defining the terrain dataset.
9. Click Run to execute the tool.

Run the Build Terrain tool

The Build Terrain tool performs the necessary steps to make a terrain dataset functional after it has been initially defined.

1. Open the Build Terrain tool.
2. Click the Input Terrain button and browse to the feature dataset where the terrain dataset resides.
3. Select the terrain dataset and click OK.
4. Optionally specify Update Extent.

   Update Extent recalculates the data extent of a window-size-based terrain dataset when the data area has been reduced through editing. It is not needed if the data extent has increased or if the terrain dataset is z-tolerance based. It will scan through all the terrain data to determine the new extent.

5. Click Run to execute the tool.