Generate depth areas

Disponible avec une licence 3D Analyst.

Depth areas are geographic features used to depict depth ranges between contours in S-57- and S-100-based products. The Generate Depth Areas tool uses a triangulated irregular network (TIN) and contour lines as input for creating and attributing the depth polygons. 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.

Prepare raster data for generating depth areas

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

1. Start ArcGIS Pro.
2. Open a new or an existing project.
3. On the Analysis tab, in the Geoprocessing group, click Tools.
4. In the Geoprocessing pane, expand 3D Analyst Tools.
5. Click Raster > Conversion > Raster To TIN.
6. Configure the Raster To TIN tool parameters:
   1. For the Input Raster parameter, choose the raster that contains bathymetric data.
   2. Set the Output TIN location.
   3. Ensure that the value in the Maximum Number of Points parameter matches the number of individual pixel values of the raster.
   4. Set the Z-tolerance value to 0.

      Setting the Z-tolerance value to 0 ensures that the depth value is not altered during conversion.

   5. Leave the default values for all of the other parameters.
7. Click Run to generate the TIN dataset.

   A TIN dataset is generated from the input raster data.

8. Optionally, use the Smooth Bathymetric TIN tool 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.
9. In the Geoprocessing pane, click the Back button to return to the Toolboxes list.
10. Click Triangulated Surface to expand and click Surface Contour.
11. Configure the Surface Contour tool parameters:
    1. For the Input Surface, choose the TIN dataset you created.
    2. Set the Output Feature Class location.
    3. For the Contour Interval parameter, provide an interval value.
    4. Type VALDCO in the Contour Field parameter to match the field name in the ENC standard.
    5. 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.
    6. Leave the default values for all of the other parameters.
12. Click Run to generate the depth contours.

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

Remarque :

Generated contours may have topological errors depending on the resolution of the bathymetric surface, designated contour interval, and how much smoothing was applied. Review your contour data and address any issues before running Generate Depth Areas.

Prepare point data for generating depth areas

First, you must understand some information about the 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.

Remarque :

Point data can come in a variety of formats. Since XYZ data is one of the most common formats used in navigational charting, this workflow focuses on starting with XYZ data. If you have point data in a geodatabase, you can skip to step 13.

Complete the following steps to generate depth areas from point data:

1. Start ArcGIS Pro.
2. Open a new or an existing project.
3. On the Analysis tab, in the Geoprocessing group, click Tools.
4. In the Geoprocessing pane, expand 3D Analyst Tools.
5. Click the Statistics toolset, and click Point File Information.

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

6. Configure the Point File Information tool parameters:
   1. For the Point Data parameter, choose the file containing the XYZ data.
   2. Set the Output Feature Class location.
   3. For the File Format parameter, choose ASCII file with XYZ.
   4. Choose the coordinate system of the XYZ coordinate data for the Coordinate System parameter.
   5. For the Decimal Separator parameter, choose the value based on the XYZ data format.
7. Click Run.

   A polygon attributed with information about the point data is generated.

8. In the Contents pane, right-click the output layer from the Point File Information tool and click Attribute Table.

   The attribute table contains statistical information about the point data. The range of Z_Min and Z_Max values allows you to determine whether the data is positive up or positive down. In positive down data, maximum depth and minimum depth values are negative with drying heights as positive. In positive up data, the maximum depth and minimum depth values are negative with drying heights as positive. The Pt_Spacing value is used in the ASCII 3D To Feature Class tool.

   Attribute value	Description
   Pt_Spacing	The average space between points in the dataset
   Z_Min	The minimum z-value (if the data is positive up)
   Z_Max	The maximum z-value (if the data is positive up)

9. In the Geoprocessing pane, click the 3D Features toolbox, and click the Conversion toolset.
10. Click ASCII 3D To Feature Class to convert the XYZ file to a multipoint feature class.
11. Configure the ASCII 3D To Feature Class tool parameters:
    1. For the ASCII 3D To Feature Class parameter, choose the file that contains the XYZ data.
    2. For the File Format parameter, choose XYZ.
    3. Set the Output Feature Class location.
    4. For the Output Feature Class Type parameter, keep the default Multipoint features value.
    5. Choose the coordinate system of the XYZ data for the Coordinate System parameter.
    6. For the Average Point Spacing parameter, type the value from the Pt_Spacing attribute from the polygon output of the Point File Information tool.
    7. For the Decimal Separator parameter, choose the value based on the XYZ data format.
    8. Leave the default values for all of the other parameters.
12. Click Run.

    A multipoint feature class is generated.

13. In the Geoprocessing pane, click the Back button to return to the Toolboxes list.
14. Click TIN Dataset > Create TIN.
15. Configure the Create TIN tool parameters:
    1. Set the Output TIN location.
    2. For the Coordinate System parameter, choose a suitable projected coordinate system.
    3. For the Input Feature Class parameter, choose the multipoint feature class that was generated from the ASCII 3D To Feature Class tool.
    4. Leave the default values for all of the other parameters.
16. Click Run to generate the TIN dataset.

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. The Delineate TIN Data Area tool can be used to eliminate the long connections.

17. In the Geoprocessing pane, click the Back button to return to the Toolboxes list.
18. Click TIN Dataset to expand and click Delineate TIN Data Area.
19. Configure the Delineate TIN Data Area tool parameters:
    1. For the Input TIN parameter, choose the TIN dataset generated from the Create TIN tool.
    2. Type a value in the Maximum Edge Length parameter text box.

       Remarque :

       Connections between points are removed based on the maximum edge length. When working with irregularly spaced points, the recommended value for the maximum edge length is two times the square root of the average point spacing.

    3. Leave the default values for all of the other parameters.
20. Click Run.
21. Optionally, use the Smooth Bathymetric TIN tool to perform a shallow-biased smoothing of the generated TIN 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.
22. In the Geoprocessing pane, click the Back button to return to the Toolboxes list.
23. Click 3D Analyst Tools > Triangulated Surface > Surface Contour.
24. Configure the Surface Contour tool parameters:
    1. For the Input Surface, choose the TIN dataset you created.
    2. Set the Output Feature Class location.
    3. For the Contour Interval parameter, provide an interval value.
    4. Type VALDCO in the Contour Field parameter to match the field name in the ENC standard.
    5. 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.
    6. Leave the default values for all of the other parameters.
25. Click Run to generate the depth contours.

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

Remarque :

Generated contours may have topological errors depending on the resolution of the bathymetric surface, designated contour interval, and how much smoothing was applied. Review your contour data and address any issues before running Generate Depth Areas.

Generate depth areas

Once the raster or point data is processed and you have the TIN and contour inputs, you are ready to generate depth areas.

Remarque :

Before generating the depth areas, it is recommended that the contours be appended to the DepthsL feature class in the Nautical workspace with the S-57 schema.

Complete the following steps to generate depth areas:

1. If necessary, create an ArcGIS Maritime database schema and add the NIS data to the Contents pane.

   The Maritime S-57 tab appears.

2. On the Maritime S-57 tab, in the S-57 Editing group, click the Compilation Scale drop-down arrow and choose a scale.
3. In the Geoprocessing pane, click the Back button to return to the Toolboxes list.
4. Click Maritime Tools to expand and click Generate Depth Areas.
5. Set the parameters as follows:
   1. For the Input TIN parameter, choose the TIN dataset that was used to generate the depth contours.
   2. For the Input Contour Features parameter, choose the layer (such as DepthsL) containing the depth contours that were generated from the TIN.
   3. For the Depths Field parameter, verify that the value is set to VALDCO.
   4. For the Depth Direction parameter, choose the direction based on the depth data.
   5. Optionally, indicate the Extent Plygon Features in which the depth area polygons will be generated.

      If none is specified, the TIN domain will be used.

      Remarque :

      The TIN domain is a polygon feature representing the interpolation zone of the TIN dataset.

   6. Set the Target Workspace parameter to the geodatabase where you want the depth areas to be generated.

      This database must contain the S-57 schema.

   7. Type values for the Minimum Depth and Maximum Depth parameters.

      The minimum depth value is used to populate the minimum depth of polygons that are more shallow than the shallowest contour value. The maximum depth value is used to populate the maximum depth value of polygons that are deeper than the deepest contour value.

6. Click Run to generate the depth areas.

   The depth area polygons are generated and added to the geodatabase.

Remarque :

Regardless of the input depth direction, the tool populates the output depth fields (DRVAL1, DRVAL2) as positive with drying heights as negative. If the TIN and depth contours had the positive up depth direction, use the Calculate Field tool on DepthsL to convert the depth values to positive values, as required by the S-57 specification. This can be done by multiplying the value of the depth contour (VALDCO) by (-1).