## Introduction to basic modeling techniques

This section will introduce basic techniques that come in handy while configuring a ReconCell in VEROSIM, which comprises **selecting**, **adding** and **moving** objects/3D geometries.

### Selecting objects

All selections happen graphically. You can either select something by clicking it in the Explorer widget, or by clicking in the Render Window. The selection mode for the latter case needs to be activated in the `Selection Mode` toolbar, though. Selections inside the explorer widgets are possible at all times.

![](modeling_selection.png "")

As soon as something is selected it will be highlighted in the Explorer widget and in the Render Window. This is the indicator for you to know that you can edit properties of the selected object (in the Properties widget). Selection changes as soon as you click another object and multiple selections are also possible by holding the `Ctrl` key while clicking.
To deselect something you need to use the keyboard shortcut `Ctrl+Del`.

#### Disabling the selection visualization

Sometimes it is not desirable to see the selection in the render window. This feature is a project specific setting that you can change by navigating to the menu bar `File -> Project properties...`. A new dialog window will open up. Select `Rendering`, then `Selection` and deactivate the `Mark selection` checkbox. Here, you can also make more subtle changes, like disabling or changing the color of the bounding box, or changing the style of the coordinate system.

![](modeling_selectionvisu.png "")

### Adding primitive geometries
Adding boxes and other primitive geometries in VEROSIM is an easy task. Geometry can be placed in the database below 3D Nodes. This is a constraint that is necessary because geometry needs a position and an orientation, otherwise you could not locate it in threedimensional space. In your open project select any `childNodes` reference list and open the context menu. Add a `VSD3D::Node` by clicking `New -> 3D node`.

![](modeling_new3dnode.png "")

If you already have a 3D Node or you have just created one and you now want to add a primitive, you will need to open the context menu on that 3D Node's `childNodes` reference list. Afterwards, go to `New` and select the geometry you want to add (e.g. a `Hull node (Box)`).

![](modeling_newbox.png "")

### Importing objects from CAD

Importing from CAD files is handled by simple drag and drop operations. Select a CAD file (STL, STEP, 3ds, ...) in the file manager of your choice. Use your mouse to drag it into the VEROSIM window and drop it. The model data will be imported and converted into VEROSIM datatypes. Afterwards, handle the imported object in the same way as you would handle manually added geometries.

### Moving objects

Three-dimensional objects can be moved and reoriented in a graphical fashion. If an object that can be modified in such a way is selected, the `Properties` widget will contain the `Modify frame` widget. By unfolding that widget you will have the graphical means at hand to modify an objects pose. The `Base system` selects the coordinate system the modification is relative to, while the `Translation` and `Rotation` perform the actual modification action. You can also change the increment by which a value in the spin boxes will be changed. Axes are color-coded so that you can identify along which axis an action is performed: Red - x-Axis; Green - y-Axis; Blue - z-Axis

![](modeling_selectionmodify.png "")


In addition to the widget, you will find three-dimensional handles in the render window that allow you the same modifications, with the exception that you can perform them directly in three-dimensional space in the render window. These handles belong to a coordinate system that we call `Gizmo`. Move your mouse to the render window and drag the handles around. You will notice that the movements you can actually perform are constrained to either single axis or planes. Modifications with the Gizmo will of course also be visible in the Modify frame widget.

![](modeling_selectiongizmo.png "")