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Need the real levels of an uneven slab or site from a scan? Calculate Surface measures the Revit point cloud surface on a grid and places a reference point at each measured height, ready to shape floors, roofs and toposolids.
Calculate Surface measures the surface height from the point cloud at regular grid points over a reference floor and places a ZetaRefPoint at each measured point. You then use Floor By Points, Roof By Points or Topo By Points to shape the element to these points.
Click Calculate Surface (Zeta BIM tab › PointCloud Tools).
Pick the reference floor.
Set the options (see below) and click Create.

Wait for the progress window. Closing it cancels the whole run; nothing is added.
ZetaRefPoints appear on the surface. Select them with Floor / Roof / Topo By Points.
| Option | Default | Meaning |
|---|---|---|
| Grid Size | 1000 mm (40 in) | Distance between measured points. Smaller = more detail, more points. |
| Tangent tolerance | 30 mm (1 in) | Size of the area read around each grid point. Increase it when the point cloud is sparse. |
| Reference Height Limit | 2000 mm (80 in) | How far above the reference floor the tool looks for the surface. |
| Border | On | Also places points along the edges of the reference floor. |
| From Value | Lowest value | Take the lower side, the middle or the upper side of the measured surface. Average value suits most scans. |
Settings are remembered separately for metric and imperial projects.
ZetaBIM is a Revit plugin for scan-to-BIM teams. See the complete guide to the Revit point cloud plugin workflow. Download ZetaBIM to try it, browse more ZetaBIM tutorials, or watch the videos on the ZetaBIM YouTube channel.