This solution describes the process of terrestrial image data processing and orthomosaic generation in planar projection. Planar projection type may be useful for projects concerning facades or other similar vertical surfaces. 

The main stages of processing are the same as when building a 3D model. Main stages of the workflow: 

  • add photos;
  • creating of masks;
  • align photos;
  • build dense cloud;
  • build mesh;
  • build orthomosaic.

Add Photos

1. To add photos select Add Photos... command from the Workflow menu. 


2. In the Add Photos dialog browse the source folder and select files to be processed.


Create masks

Recommended to mask all irrelevant elements on the source photos. Find more information in tutorial - Masks. 


Align photos

1. Select Align Photos command from the Workflow menu. 


2. Set following recommended values for the parameters in the Align photos dialog: 

3. Click OK button to start photo alignment. 


Build Dense Cloud

1. Select Build Dense Cloud command from the Workflow menu. Set the following recommended values for the parameters in the Build Dense Cloud dialog:

2. Click OK button. 

Points from the dense cloud can be removed with the help of selection tools and Delete/Crop instruments located on the Toolbar.


Build Mesh

After dense point cloud has been reconstructed it is possible to generate polygonal mesh model based on the dense cloud data. Alternatively the depth maps based mesh generation option can be used.


1. Select Build Mesh command from the Workflow menu. Set the following recommended values for the parameters in the Build Mesh dialog: 

Note: if at the previous stage - Depth maps was built and save in project, we recommend using the parameter - Reuse depth maps. 


2. Click OK button to start building geometry. 



To build the Orthomosaic (planar projection)

Metashape Pro allows to project the orthomosaic onto a plane set by the user, providing that mesh is selected as the surface type. The projection plane can be determined by a set of markers (if there are no 3 markers in a desired projection plane it can be specified with 2 vectors, i. e. 4 markers).

We suggest the reconstruction of orthomosaic in a planar projection mode using of the two following methods: Current view and using Markers.


Note: 

  • Build Orthomosaic procedure can be performed only for projects saved in PSX format for chunks with the existing mesh or DEM.
  • More then one instance of Orthomosaic can be stored in one chunk. In case you want to save current Orthomosaic instance and build new one in current chunk, right-click on Orthomosaic on the Workspace pane and uncheck "Set as default" option. In case you want to save current Orthomosaic instance and edit its copy, right-click on Orthomosaic and choose "Duplicate" option. 


Current View:


1. Select the Build Orthomosaic... command from the Workflow menu. 


2. In the Build Orthomosaic dialog box select parameters for building orthomosaic. We selected - Current View for building Orthomosaic.


3. Click OK button when done. 


4. The progress dialog box will appear displaying the current processing status. To cancel processing click Cancel button.


Markers:


To set axes using markers, you should add markers to the project. You can place markers on the surface of the model and outside it. 


Markers that will be located outside the model surface, the model should be georeferenced or have a scale bar (how to create scale bar instance:- https://agisoft.freshdesk.com/a/solutions/articles/31000148855)Then after creating a marker, you can enter the coordinates of the marker on the Reference pane.


We set markers on the wall of the building without inputting their reference coordinates. 

Open Mesh or Dense cloud on the Model view and place markers on the object that will define our axes (select Add marker command from the context menu). We used 3 markers to define the projection plane. 



NOTE: 

  • for more accurate marker placement we recommend to adjust markers' projections on the images in the Photo view mode. 


In case it it required to get an orthomosaic of a part of a building (for example, the left part of the building facade), you can either change the Bounding box or set the area of interest in the Build Orthomosaic dialog window (enable checkbox - Setup boundaries and choose a region). The latter option is applicable for georeferenced projects only.


1. Select the Build Orthomosaic... command from the Workflow menu. 


2. In the Build Orthomosaic dialog box select parameters for building orthomosaic. Here Markers option is selected for building Orthomosaic. Specify Horizontal or Vertical axis' (using created markers). These option defines which direction, defined by the pair of markers, will be used as a horizontal or vertical direction of the output orthomosaic raster.


3. Click OK button when done. 


4. The progress dialog box will appear displaying the current processing status. To cancel processing click Cancel button.