Using a surface as a hide boundary in Civil 3D allows you to exclude certain areas of a surface from being displayed or triangulated. This is useful for removing unwanted portions of a surface, such as areas underneath structures or other overlapping surfaces.<br /><br />Steps to Use a Surface as a Hide Boundary<br />1. Prepare the Drawing<br />Ensure you have a TIN Surface in the drawing.<br />Identify or create the boundary area that you want to hide. This could be a polyline or feature line representing the boundary.<br />2. Open Surface Properties<br />In the Toolspace palette, go to the Prospector tab.<br />Expand the Surfaces collection and find your surface.<br />Right-click the surface name and select Surface Properties.<br />3. Define the Boundary<br />Access the Definition:<br /><br />Expand the surface node in the Prospector tab.<br />Right-click Definition and select Add Boundaries.<br />Set Boundary Properties:<br /><br />In the Add Boundaries dialog box:<br />Type: Choose Hide as the boundary type.<br />Name: Assign a name to the boundary (e.g., "Structure Hide").<br />Non-destructive Breakline: Leave unchecked unless you want the boundary to affect triangulation without excluding data.<br />Click OK.<br />Select the Boundary Object:<br /><br />Select the polyline or feature line representing the area to hide.<br />The boundary is applied, and the selected area is excluded from the surface.<br />4. Update the Surface<br />The surface triangulation is updated, and the hidden area no longer contributes to contours or display.<br />Additional Tips<br />Boundary Hierarchy: Ensure the hide boundary is applied after any other boundaries (like outer or show boundaries) to avoid conflicts.<br />Closed Objects: The polyline or feature line used for the boundary must be closed.<br />Edit the Boundary: To modify the hide boundary, adjust the geometry of the polyline or feature line, and the surface will update dynamically.<br />Use Case Examples<br />Hiding Structures: Exclude building footprints or other features from the surface.<br />Multiple Boundaries: Use multiple hide boundaries to manage complex surfaces with overlapping exclusions.<br />Refining Visualizations: Clean up the display of surfaces in profile or plan views by removing unnecessary areas.
