# Creating a surface from existing points

If you have three or more 3D points in the job, you can create a surface and store it as a triangulated terrain model (TTM) file in the current project folder. You can then use the surface to calculate a volume. See Compute volume.

1. In the map, select three or more 3D points.
2. Tap and hold in the map and select Create surface.

3. Enter the surface name. Tap OK.

   The surface is linked to the current job as a linked map file and appears in the map.

To change the appearance of the surface

1. In the map, tap and select Settings.
2. In the Surface group, select one of the following from the Display field:
   - Color gradient
   - Shaded
   - Triangles
   - Color gradient + triangles
   - Outline

3. If required, in the Offset to surface field, specify an offset to the surface. Tap to select whether the offset is to be applied vertical or perpendicular to the surface.

To modify the surface

You may need to modify the surface before performing a volume calculation.

To modify the surface, you must have only one TTM model displayed in the map, which must be set to visible and selectable. To change visibility/selectability settings, tap in the map toolbar to open the Layer manager and select the Map files tab. In addition, the surface must be displaying triangles in the map. To enable this, tap in the Map toolbar and select Settings. In the Surface group, select Triangles or Color gradient + triangles in the Display field.

1. Tap and select Plan.

2. In the map, select one or more triangles in the surface.

   A triangle can be selected only if no other items, such as points, are selected. To make triangle selection easier, hide other items using the Filter tab in the Layer manager. To select triangles, the map must be in Plan view.

3. Tap and hold in the map and select Delete selected triangles. This option is not available if you selected all the triangles in the surface.
4. Tap OK.