This article offers the solution for the problem that frequently occurs when editing a point cloud or a mesh model. The regular selection tool selects the area in all available planes of the model, thus if an area of a wall of a building is selected, the same area on the opposite wall will also be selected. To solve this problem there are several approaches that are described in this article:
Visible selection (for Dense Cloud and Mesh)
Visible Selection tool is implemented in Metashape Pro and Standard editions starting from the version 1.8.1. The tool allows to limit the selection depth, so that only the area of the mesh that is visible in the Model view would be selected. The tool can applied to the Dense Cloud and to the Mesh.
To enable Visible Selection tool - choose the corresponding option from the Selection tools list on the Toolbar, as illustrated in the animation below:
When Visible Selection is enabled the corresponding inscription appears in the upper right corner of the Model view window.
Position the model that way so that the area of interest is visible in the Model view, then enable Visible Selection and use selection tool for the area of interest:
Compare the result above (with Visible Selection enabled) to the result below (without Visible Selection enabled):
Also there are following options for the Selection tool available from Edit menu:
- Invert Selection (for Dense cloud and Mesh):
- Grow Selection (for Mesh only). The selected area will increase along its' perimeter. This option is also available with the hotkey - Page Up:
- Shrink Selection (for Mesh only). The selected area will decrease along its' perimeter. This option is also available with the hotkey - Page Down:
- Reset Selection (for Dense Cloud and Mesh). Cancels the selection:
Filter points by selection
In some cases the point cloud needs to be edited before a model is generated from it. In order to edit only some areas of the point cloud (and not the entire point cloud) it is recommended to use the Filter points by selection tool.
For example, if the windows are poorly reconstructed (because of the limitations for glass surface, extra glare, and so on) it is possible to improve the resulting model using the following approach: remove the poorly reconstructed windows from the point cloud, then build a model from the Dense Cloud and use the Close Holes tool to get a smoother geometry.
An alternative approach for editing the model rather then the point cloud is described in the Filter by selection for mesh section of this article.
Select approximately the area of interest using the selection tool:
Then in the Tools menu select Dense cloud > Filter by selection:
Since Visible selection tool as not enabled an additional part of the point cloud (that was behind the selected area) is selected as demonstrated in the animation below:
To deselect a part of the point cloud, hold down the Shift key and select the area that you want to deselect (to add a selection area, use the Ctrl key):
To hide the deselected area from the Model View select the Filter points by selection option again (Tools > Dense cloud > Filter by selection)
When the area of interest on the point cloud is isolated - it can be positioned conveniently for editing. In the example below the points in the glass windows area are to be removed. For the purpose use the Delete key on the keyboard or Delete Selection button on the Toolbar:
To display the entire point cloud after a part of the point cloud has been edited, run Tools > Dense Cloud > Reset Filter.
The entire Dense Cloud with the applied changes will be displayed in the Model view:
To build a Mesh model with the applied changes use the edited Dense cloud as the Source data in the Build Mesh dialog available from the Workflow menu:
It important to remember that only the point cloud is edited and the depth maps are not. So if you building a Model from Depth maps, then the changes you made on the point cloud will not be taken into account.
Filter by selection for mesh
Filter by selection is also applicable to Mesh when you want to edit an area on the model. For example it can be necessary do delete an area that is curved into the mesh, as illustrated in the example below. For the purpose select the area of the model using the selection tool and then select Tools > Mesh > Filter by selection:
Position the model to delete the area that is curved into the model:
Use Reset Filter feature (Tools > Mesh > Reset Filter) to display the entire mesh in the Model view:
It is also possible to apply Mesh editing tools (such as Decimate Mesh, Smooth Mesh and Close Holes) to the selected area. For the purpose use the checkbox Apply to selection available in the particular tool dialog window (see an example below):