Concepts#

This section introduces the fundamental concepts behind Mosaic and explains the main components of the user interface.

UI Layout#

The Mosaic interface consists of several key components:

  1. Menu Bar: Access to file operations, view settings and help (on macOS its in the top menu)

  2. Tab Bar: Switches between major functional areas

    • Segmentation: Work with point cloud data and analyze object properties

    • Parametrization: Create and operate on mathematical models

    • Intelligence: Advanced features (Dynamically Triangulated Surface simulations, constrained template matching, membrane segmentations)

  3. Ribbon Toolbar: Context-specific tools for the active tab

  4. Object Browser: Lists and manages loaded data with:

    • Visibility indicators with data types

    • Context menus for operations

    • Editable names

  5. 3D Viewport: Main visualization area with:

    • Navigation controls

    • Orientation indicators

    • Optional coordinate axes

  6. Status Bar: Shows current interaction mode and application status

Additional dock widgets such as the Volume Viewer will be displayed at the bottom of the window.

../_static/tutorial/mosaic_layout.png

Mosaic interface layout.#

Object Browser#

../_static/tutorial/mosaic_object_browser.png

Object Browser#

The Object Browser is your central hub for managing all data in Mosaic. It displays all loaded objects in two main categories:

  • Clusters: Point cloud objects, e.g. a segmentation, where each point is defined by:

    • Position vector (X, Y, Z coordinates)

    • Normal vector (surface orientation)

    • For oriented data (e.g., protein picks): Full 3D orientation matrix

  • Models: Geometric shapes and surfaces including:

    • Fitted primitives (spheres, ellipsoids, cylinders)

    • Triangulated meshes

    • DTS simulation trajectories.

The symbol next to each object indicates the data type. The color of the symbol indicates if the object is shown or hidden.

  • Single click: Select one object

  • Double click: Edit object name

  • Ctrl+click: Add to selection

  • Ctrl+A: Select all objects

  • Shift+click: Select range

Context Menu#

../_static/tutorial/mosaic_context.png

Context menu with options#

Right-click any object in the Object Browser to access:

  • Show/Hide: Toggle visibility

  • Duplicate/Remove: Copy or delete objects

  • Representation: Modify how objects appear

  • Export: Save to various formats

  • Properties: Set rendering properties.

Interaction Modes#

Mosaic provides multiple interaction modes for selecting and modifying different types of data. The current mode is always displayed in the status bar at the bottom of the window and indicated by the cursor color.

Tip

Every mode can be exited by pressing the key used to enter it or via Esc. Modes can also be activated via the Interaction category in the menu bar.

Viewing Mode (Default)

  • Default camera navigation mode

  • Use mouse to rotate, pan, and zoom the 3D viewport

  • Press Esc to return to viewing mode from any other mode

Point Interaction#

Area Selection (Rubber Band)

  • Press r to activate rectangular selection mode

  • Click and drag in the 3D viewport to select points within a rectangular area

  • Press e to expand selection to entire connected clusters

  • Press r again or Esc to exit selection mode

Point Drawing

  • Press a to activate drawing mode

  • Click anywhere in the 3D viewport to add new points to the selected cluster

  • If no cluster is selected, a new cluster will be created automatically

  • Press a again or Esc to exit drawing mode

Curve Drawing

  • Press Shift+A to activate curve drawing mode

  • Click to place points along a curve path

  • Press Enter to save the curve as a new cluster of points

  • Press Shift+A or Esc to cancel curve drawing

  • Optional: Fit a curve model to the created cluster to parametrize it.

Object Selection#

Object Picking

  • Press E to activate object picking mode

  • Click directly on objects (clusters or models) to select them

  • Press s to switch between cluster and model selection targets

  • Selected objects are highlighted and selected in the Object Browser

Mesh Editing#

Mesh Delete

  • Press q to activate mesh face selection mode

  • Click on triangular faces to select them

  • Press Delete to remove selected faces

  • Press q or Esc to exit

Mesh Add

  • Press Q to activate mesh addition mode

  • Click on three points to create a new triangular face

  • If any point is a vertex in an existing mesh, the face will be added to it

  • Press Q or Esc to exit

Coordinate System#

Mosaic does not handle spatial units internally. Instead, imported data is immediately transformed into a consistent reference frame based on the sampling rate (typically Ångstroms for molecular data). This sampling rate is provided by the user or can be extracted from the header of particular file formats, e.g., mrc files.

Assuming a segmentation is loaded from an mrc file with a sampling rate of 6.80 Ångstroms per voxel, Mosaic will multiply the voxel coordinates with the sampling rate. Therefore, the internal scale would be in Ångstroms. The sampling rate also affects:

  • Display size

  • Filtering operations

  • Distance measurements

  • Export operations

Mosaic uses a right-handed coordinate system:

  • X-axis: Horizontal (left to right)

  • Y-axis: Vertical (bottom to top)

  • Z-axis: Depth (back to front)

The standard orientation is (0, 0, 1).

Next Steps#

Now that you understand the basic concepts and layout of Mosaic, proceed to the Working with Data section to learn how to handle different data types.