Generate depth areas

Disponible avec une licence 3D Analyst.

Depth areas are geographic features used to depict depth ranges between contours in Electronic Navigational Charts (ENC). The Generate Depth Areas tool uses a TIN and contour lines as input for creating and attributing the depth polygons. This tool can be used for generating depth polygons for S-57- or S-100-based products. The source for the TIN can be points, in which the point spacing can be irregular, or a raster, in which the point spacing can be regularly gridded.

The process for generating the TIN varies depending on whether the input is points or raster.

Generate depth areas from a raster

If the input to the workflow is raster data, follow the steps below to generate depth areas:

1. Start ArcGIS Pro.
2. In the Geoprocessing pane, expand 3D Analyst Tools.
3. Click Raster > Conversion > Raster To TIN.

   Alternatively, choose the Smooth Bathymetric TIN tool from Maritime Tools to perform a shallow-biased smoothing on the data to cartographically improve the appearance of the contours and depth areas.

   Remarque :

   If you smooth the TIN, you must use the smoothed TIN and contours generated from the smoothed TIN as the inputs to the Generate Depth Areas tool.

4. Click Triangulated Surface > Surface Contour.
   1. For the Contour Field Precision parameter, you must choose at least one unit of precision to comply with S-57 and S-100 navigational products.
   2. If the data was positive up, choose a value of 1 for the Z Factor parameter to make the data positive down, which is the standard for S-57 and S-100 data.

   You now have the TIN and contour inputs required to run the Generate Depth Areas tool.

Generate depth areas from point data

Point data can come in a variety of formats. Since XYZ data is one of the most common formats used in navigational charting, the focus is on starting with XYZ data. If you have point data in a geodatabase, you can skip to step 5.

First, you need to understand some information about your point data to ensure the proper creation of the TIN. This information includes the minimum and maximum depths, whether the data is positive up or positive down, and the average point spacing. To do this, use the Point File Information geoprocessing tool.

1. In the Geoprocessing pane, expand 3D Analyst Tools.
2. Click Statistics > Point File Information.

   The output of the tool is a polygon attributed with information that is used later in the workflow.

3. On the Edit tab in the Selection group, click the Attributes button .

   The outputs of the Point File Information tool are displayed.

   Attribute value	Description
   Pt_Spacing	The average space between points in the dataset. Determine from the range of values whether the data is positive up or positive down.
   Z_Min	The minimum z-value (if the data is positive up).
   Z_Max	The maximum z-value (if the data is positive up).

4. Click 3D Features > Conversion > ASCII 3D To Feature Class to convert the XYZ file to a multipoint feature class.
   • For the Output Feature Class Type parameter, choose Multipoint features from the drop-down list.
   • For the Average Point Spacing parameter, type the value from the Pt_Spacing attribute from the polygon output of the Point File Information tool.
5. Click TIN Dataset > Create TIN.
6. Use the multipoint feature class that was generated from the ASCII 3D To Feature Class tool to generate a TIN.

   The resulting TIN has connections between points that are not valid, since there is no limit on the length of the edges used to connect points during the triangulation.

7. Click TIN Dataset > Delineate TIN Data Area.

   Connections between points are removed based on a maximum edge length.

   Remarque :

   When working with irregularly spaced points, apply 2 times the square root of the average point spacing.

8. Optionally, in the Geoprocessing pane, expand Maritime Tools, and click Smooth Bathymetric TIN.

   This allows you to perform a shallow-biased smoothing on the data to cartographically improve the appearance of the contours and depth areas. If you smooth the TIN, you must use the smoothed TIN and contours generated from the smoothed TIN as the inputs to the Generate Depth Areas tool.

9. Click 3D Analyst Tools > Triangulated Surface > Surface Contour.
   • For the Contour Field Precision parameter, you must choose at least one unit of precision to comply with S-57 and S-100 navigational products.
   • If the data was positive up, choose a value of 1 for the Z Factor parameter to make the data positive down, which is the standard for S-57 and S-100 data.

   You now have the TIN and contour inputs required to generate depth areas.