Point clouds and splats
Three kinds of geometry are drawn as a point cloud: a PLY file with no faces and no edges, a glTF primitive in POINTS mode, and an OBJ p element. A cloud split across several primitives, as large glTF exports often are, is measured as one cloud, so every piece is drawn the same way.
How a cloud is drawn
Each point is sized from the cloud's spacing, the typical distance between neighbouring points, so the cloud keeps the same appearance at every zoom level.
| Cloud | Drawn as |
|---|---|
| Every point is fully opaque | Round discs one and a half times the spacing across, which close the gaps an irregular scan leaves |
| Any point stores an opacity below 1, such as a CT or MRI scan exported with its transfer function | Soft round splats, sorted by distance from the camera and blended from the back to the front |
A PLY point cloud is drawn in its stored colours without lighting.
A translucent cloud of more than a million points is drawn from a reduced set of its points, at half resolution, while the view is moving. The full cloud is drawn again shortly after the view stops. Images rendered in Photo Mode or from the command line always use the full cloud.
Density
A translucent cloud gets a Density section in the Info tab. Its slider runs from 1% to 400%. At 100%, each point is drawn with the opacity stored in the file; lower values thin the cloud, and higher values thicken it. The setting changes only the view, is not saved, and is kept until the file is closed.
Gaussian splat files
A PLY file written by 3D Gaussian Splatting training is drawn as Gaussian splats. Solidly recognizes such a file when it has no faces or edges and every vertex carries the f_dc_0 to f_dc_2, opacity, scale_0 to scale_2, and rot_0 to rot_3 properties. Each splat is drawn with its own colour, opacity, size, and orientation, and the splats are sorted and blended in the same way as a translucent cloud.
Only the base colour is drawn. The view-dependent colour stored in the f_rest_* properties is not used, so a splat has the same colour from every direction. Splats cast and receive no shadows, and a splat file has no Density section.
Summary and orientation
A file made only of points reports a Points row in the Info tab's Summary in place of vertex and index counts.
A PLY point cloud gets the Info tab's Orientation buttons, and its turns are applied to the points when the file is saved, as they are for a surface. It has no Auto Orient button, since there is no surface to examine. For a Gaussian splat file, Edit ▸ Rotate Model and the Orientation buttons turn only the view. The file is not marked as edited, and saving writes the splats in their original orientation. See Rotating the whole model.