Turn a Point Cloud Scan into a Cylinder Screen Surface

Fit a cylinder to a region of an imported point cloud scan and create a sized, positioned cylinder screen surface from it. The surface covers only the arc the scan actually has points on, and an optional soft-edged mask limits projection to the scanned area.

Before you start

• An E57 point cloud scan imported into your project — see Import an E57 Point Cloud Scan
• The scan covers a cylindrical or partly cylindrical surface (a curved screen, an arched bay, a dome section)

Steps

1. Select the point cloud and open Surface from Scan

Select the point cloud object in the scene tree. In the Inspector, scroll to the Surface from Scan section and expand it.

2. Add crop boxes to isolate the surface

Click Add Crop Box to add a box that starts covering the whole cloud. Set its Mode to Include to keep only the points inside it, or Exclude to remove them. Adjust Center, Rotation and Half Size to trim the box down to the screen region. Points outside the crop are dimmed in the scene view. You can add up to eight boxes.

3. Choose the fit options

Set Inlier Threshold (mm) to control how far a point may lie from the cylinder and still count as part of it (default 20 mm). Raise it for a rough or noisy scan; lower it to separate the surface from a frame that sits only a little in front of it.

Set Cylinder Axis to Free (default) to let the axis point any way, or constrain it to Vertical or Horizontal to steady the fit when the surface is partial or the scan is noisy.

4. Run the fit

Click Fit Cylinder. When the fit succeeds, two readout lines appear:

• Radius / Height / Opening — the fitted cylinder's radius, the length along its axis that the points cover, and the arc angle.

• RMS / Max / Inliers — the average and maximum distance of the inlier points from the cylinder, and the share of kept points that fall within the threshold. A low Inliers percentage means the region is not very cylindrical.

If the fit fails, the reason is shown in place of those lines — typically too few points or no cylinder in the cropped region. Adjust the crop boxes or raise the threshold and try again.

5. Check with the deviation heatmap

Enable Show Deviation Heatmap to colour every point by its distance to the fitted cylinder: green within the inlier threshold, shading through yellow to red further away. Adjust Heatmap Range (mm) (default 100 mm) to set how far beyond the threshold the colour reaches full red. Use the heatmap to confirm that the screen area is green and non-screen parts (frames, ribs, the floor) shade to red.

6. Configure the mask (optional)

Create Mask With Surface is on by default. When on, Create Surface also writes a soft-edged mask image and plays it on a sequencer one layer above the others on the surface, blended with Multiply. The mask cuts projection to the area the scan covers — surroundings that bend toward the viewer, such as a frame around arched bays, end up black.

Before creating the surface, set the mask controls if the defaults do not suit the installation:

• Mask Tolerance (mm) (default 20 mm) — how far a point may be from the cylinder and still count as surface.

• Border Offset (mm) (default 0) — positive grows the lit area outward, negative shrinks it.

• Feather (mm) (default 20 mm) — the width of the soft edge.

• Mask Resolution (mm/px) (default 5 mm/px) — how fine the mask image is. Large surfaces are capped at 8192 pixels on a side.

Clear Create Mask With Surface to create the surface alone, without the mask layer.

7. Create the surface

Click Create Surface. A cylinder screen surface appears at the top level of the scene tree, sized and placed from the fit. When Create Mask With Surface is on, the mask sequencer is added as well — both in a single undo step.

Enable Surface As Display on the new surface to use it as a display.

8. Regenerate the mask after changes

If you adjust crop boxes or mask settings after creating the surface, click Regenerate Mask to rebuild the mask image in place. The mask asset reloads by itself, so the sequencer shows the new mask without further steps.

Common Mistakes

• Fit fails or produces a wrong cylinder — the crop region includes too many non-screen points (floor, ceiling, mounting frame). Add tighter Include boxes or Exclude boxes around the obstructions. Constraining Cylinder Axis to Vertical or Horizontal can also stabilise a partial scan.

• Low Inliers percentage despite a clean crop — the threshold is too tight for the scan's noise level. Raise Inlier Threshold (mm) until the percentage reflects the actual screen coverage.

• Mask layer does not darken the surround — the GPU does not support the Multiply blend mode. A notice appears below the mask controls. The mask layer is still created but cannot blend correctly on that GPU.

• Mask edge is visible on screen — increase Feather (mm) for a wider soft edge, or use Border Offset (mm) to push the border outward so it falls off the visible screen.

Tips

• Start with one large Include box covering just the screen area, then add Exclude boxes to carve out mounting hardware. This is faster than trying to trim the Include box exactly.

• Use the deviation heatmap to check the fit before creating the surface. A good fit shows a green screen area with red falling on everything that is not part of the screen.

• The mask image is saved next to the scan file as <point cloud name>_surface_mask.png and imported as an image asset. The sequencer plays it looped and starts by itself.

• Crop boxes affect both the fit and the mask. An Exclude box carves its area out of the lit region in the mask as well.

Related

Import an E57 Point Cloud Scan — import an E57 scan into the project before starting this workflow.

Cylinder — the surface's own properties once it exists (radius, height, opening, tessellation).

Create a Display — turn the new surface into a display to route content to it.