Assign NoData to 3D Grid

Surfer's gridder allows you to assign NoData to your grid during the gridding process.  You can assign NoData outside of the convex hull of data, the alpha shape of the data, or a polygon boundary.

1. Click Home | Grid Data | Grid Data
2. In the Grid Data - Select Data dialog
   1. Click XYZC in the Data Type section.
   2. Select your preferred Gridding Method.
   3. Click Browse in the Dataset 1 field, select your XYZC data file and click Open.
   4. Select the X, Y, Z and C data columns and click Next.
3. In the Grid Data - Options dialog adjust the available parameters as needed for your data and click Next.
4. In the Grid Data - Output dialog
5. you can choose to set Assign NoData outside of to either Convex hull or Alpha shape. Alternatively, if you already have a polygon file with a 2D polygon in it, you can leave that setting set to None and then select the file under the NoData Polygon Boundary section.
   1. 

      Choose to assign NoData outside the convex hull, outside an alpha shape, or either inside or outside of a polygon boundary.

6. Give the file a name and click Finish. The 3D grid file is created with the appropriate NoData selections applied. You can use this new 3D grid to create a map and visualize in the 3D view.

Assign NoData to your 3D grid outside a 2D polygon boundary, such as an alpha shape polygon created around the original data points.

To use this feature, all you need to start with is a 3D grid file (VTK or HDF). Follow these steps:

1. Click Grids | Edit | Assign NoData.

2. To the right of Input Grid, click Browse, select your 3D grid file and click Open. Choose to import the file as 3D Grid.

3. Now you can choose to assign NoData inside or outside a 2D polygon, or above or below a surface described in a 2D grid file (or both). Make your selections in the NoData 2D Polygon Boundary and the NoData Surface Boundary sections.

   1. 

      Choose to assign NoData to a 3D grid file using a polygon boundary, another grid surface, or both.

4. Give the file a name and click OK. If a 3D grid was selected for the input grid, then the output grid is automatically a 3D grid as well. The 3D grid file is created with the appropriate NoData selections applied. You can use this new 3D grid to create a map and visualize in the 3D view.

Assign NoData above or below another 2D grid surface, such as topography to remove the gridded data above the ground surface.