MAGNET Collage Web: Extracting features

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Managing categories

To open the Category Manager, use the "Edit categories" menu option in the Layer Manager. This dialog should be used by the organization data manager to define the types of features to be used in the organization, so different users can create and extract features with consistent attributes (e.g.. all extracted buildings have the same data fields).

New Category

The Category Manager shows the tree (hierarchy) of categories. Each category inherits all the attributes from its parents.

By default, there is a root Feature category (with no attributes), and a child Annotation category with a name and a description. All categories descending from Annotation will include these attributes, which will be displayed in a popup frame by the Information tool. If a user does not want this popup to show, he/she can create categories which inherit directly from Feature.

To create a new category, select the parent one in the tree and click on the "New" button. The new category will be automatically set to Edit mode. Its name, description and attributes can be modified.

  • To save new category data, click on "Apply edit". Otherwise click "Cancel edit" to revert the changes.
  • To edit an existing category, select it in the tree and click on the "Edit" button.
  • Categories without children can be deleted by clicking on the "Remove" button

Create feature layers

  • To create a new feature layer, select the "Create layer" menu option in the Layer Manager.
  • The Create Layer dialog will appear with empty data.
  • Click on the "Select" button next to the category field to open the Category Selector. Choose the category for the new layer in the tree and click "Select".
  • The name of the selected category will now appear in the Create Layer dialog. The user must now type a layer name and select its geometry type and color.
  • The new layer will appear in the layer manager under a group with the category name.

Adding a new feature

  • Once the Layer Editing tool is active and a feature layer is selected in the Layer Manager, the Tool panel on the right side will show the editing operations available to the user.
  • After selecting the "Add feature" operation, the user can extract a new feature by picking points (from point clouds) in the 3D View. Depending on the geometry type of the selected feature layer, it will be possible to draw a point, multiple points, a polyline or a polygon.
  • For polyline or polygons, the user can add as many points as needed and then:
    • Double-click to end with a new point.
    • ESC to end without adding a new point.

Attribute values

  • The user can also type the attribute values for the new feature in the Properties/Feature panel. Text must be entered for a "name" attribute, if present.
  • Note that it is not necessary to use the Edit tool to change the attribute values in the Properties panel. It is enough to select the feature with the Information/Selection tool.
  • To save the new feature, click on the "Insert" button.

Modifying an existing feature

When a feature is selected, the Layer Editing panel offers additional tools to modify its geometry:

  • Edit the feature's geometry (move its vertices)
  • Add or remove vertices
  • Remove the feature

Edit feature vertices

  • In this mode, a feature vertex is selected, either by clicking on it in the 3D View, or in the Geometry list inside the Properties panel.
  • The selected vertex is decorated with three axes and planes. The user can use one of the axes or planes to click and drag the vertex to change its location (the active axis or plane will be highlighted).
  • Alternatively, the user can move the vertex to a point picked from a point cloud by holding SHIFT and clicking on the destination point.

Add or remove vertices

  • In this mode, new vertices can be added or removed. For lines and polygons, a vertex is selected, either by clicking on it in the 3D View or in the Geometry list in the Properties panel. The next feature segment will also be selected (highlighted in red).
  • When the user clicks on the point cloud, an intermediate vertex will be added to the feature in the middle of the highlighted segment.
  • To remove the selected vertex, just click on the trash bin icon next to the cancel button.

Remove the feature

  • This operation is used to remove the whole feature. The user needs to confirm by clicking on the "Remove" button.
  • Notice that, currently, Collage Web does not support Undo/Redo operations, so some updates are not reversible. The user will see a warning when this is the case.