# To measure to a surface

Use the Measure to surface measurement method to calculate and store the closest distance from the measured point to the selected surface model. The surface model can be a BIM model or a digital terrain model (DTM).

If more than one surface is selected, the nearest surface is used.

1. If the surface is in:
   - a DTM, tap and select Measure / Measure to surface. If there is more than one surface available, select the surface in the Select surface field.

   - a BIM model, select the surface in the map and then from the tap and hold menu select Measure to selected surface.

     To select the surface the BIM model must be displayed as a solid object and the layer containing the surface must be selectable.

     You can choose whether selecting surfaces in the map selects Individual faces or selects the Whole object. To change the Surface selection mode, tap and select your preferred Surface selection mode. See BIM model selection mode.

2. Enter the Distance to surface limit.

3. If required, enter a value in the Antenna height/Target height field.

4. Tap Start.

   If the surface is not already visible in the map, it becomes visible.

   The software calculates and reports the closest distance from the current position to the selected surface model and displays it in the Distance to the surface field. The Distance to the surface is only shown if it is within the Distance to surface limit.

   The position on the surface is highlighted in the map and a line is drawn from the measured position to the position on the surface. Negative distances are reported for positions between you and the model and positive distances are reported for positions on the other side of the model.

   If the software warns Terrain models disagree, there are overlapping surfaces with different elevations in the map. Hide any surfaces you are not using in the Map files tab of the Layer manager. See Managing map file layers.

5. Enter the Point name and, if required, the Code.

6. Tap Measure.

7. Tap Store.

   The Distance to surface value and the coordinates of the closest point on the surface are stored with the measured point and can be viewed in Review job and Point manager.