Georeference 3D editor

Functionality

With the georeference 3D editor, you can edit a georeference 3D and obtain a 3D view of your study area according to your wishes. The georeference 3D editor consists in fact of one dialog box in which you can edit 3D view parameters. Further, the georeference 3D editor has a menu bar, a context-sensitive menu and a toolbar.

To start the georeference 3D editor:

To create a new georeference 3D, you need first of all an interpolated height map (Digital Elevation Model/Digital Terrain Model). For more information on obtaining a DEM, see How to calculate a DEM.

Select for instance the Create Georeference command on the File menu of the Main window. In the appearing dialog box, select the option button Georeference 3D and select the height map and specify the size of the map window in which your 3D view will be displayed. After the Display Options - 3D Grid dialog box, a map window is opened showing an initial 3D view. In the map window, select Georeference from the Edit menu to start the georeference 3D editor.

To edit an exisitng georeference 3D, you can double-click a georeference 3D in the Catalog. After the Display Options - 3D Grid dialog box, a map window is opened showing your 3D view. In the map window, select Georeference from the Edit menu to start the georeference 3D editor.

In the Display Options - 3D Grid dialog box, you can specify whether you want to see the 3D view as grid lines with or without a drape of a raster map.

For more information on creating a georeference 3D, refer to How to create a 3D view.

Parameters of a georeference 3D or a 3D view:

Fig. 1: This picture shows you a simplified overview of how the relationship between the observer and the terrain is determined.

The options in the Georeference 3D dialog box are shortly described below.

View Angle

The View Angle is an angle in degrees which defines the aperture of the observer's sight, i.e. how much you can see of your 3D model.

When the view angle is small, only a small area of the total 3D view is observed, with the view point as the middle of the observed area.
The larger the angle, the larger the area that is observed.
A maximum of 180� is allowed.

Scale Height

The Scale Height defines how much the altitude (Z) should be exaggerated compared to the XY-scale.

A scale height of 1 means no height exaggeration.
A scale height > 1 means that vertical exaggeration is increased.

Note that when you increase the scale height, more parts of your study may fall behind exaggerated parts and can thus no longer be seen.

View Point

The View Point is the XY-location you want to look at. The Z-coordinate of this point is defined by the DEM. The view point will be drawn in the center of the map window.

Horizontal Rotation

The Horizontal Rotation is an angle in degrees to rotate the 3D view anti-clock wise from the south-north direction.

When 0� is specified, the 3D view is orientated south-north. The observer is located to the south of the DEM.
When 90� is specified, the 3D view is oriented west-east. The observer is located to the west of the DEM.
When -90� is specified, the 3D view is oriented east-west. The observer is located to the east of the DEM.

Vertical Rotation

The Vertical Rotation is an angle in degrees away from a vertical through the terrain.

When 0� is specified, the line of sight is perpendicular to the 3D view; the observer is located high in the sky and looks straight down on the 3D view.
When 90� is specified, the line of sight is parallel to the 3D view; the oberver is located on the same height as the view point and sees the 3D view in front of him.

Distance

The Distance is the distance between the observer and the view point.

When a large distance is specified, you get a general overview of the observed 3D view.
To observe the 3D view in detail, you should decrease the distance.

Location Point

The Location Point is the location of the observer in XY-coordinates.

Location Height

The Location Height is the altitude of the observer.

All changed parameters are immediately stored in your georeference 3D. To see the effect of changed view parameters, you need to redraw the map window: click the Redraw button in the toolbar of the map window, or press Ctrl+R on the keyboard.

Effects of changing 3D view parameters:

The different view parameters are illustrated in the figures below.

Fig. 2: Reference situation. The observer is standing almost in front of the DEM looking towards the north.

In the following four pictures, only one parameter is changed.

In the last picture a number of parameters are changed.


Fig. 3: The vertical rotation is decreased from 82� to 40�. The observer looks more upon the DEM.	Fig. 4: The horizontal rotation is changed from 0� to 30�. The observer is looking into the north-west

Fig. 5: The view angle is decreased from 90� to 60�. The observed part of the DEM became smaller.	Fig. 6: The view angle is increased to 120�. The observed part of the DEM became larger.

Fig. 7: Several parameters are changed, including the view point. In this way, you can find an 'optimal' 3D view, depending on the purpose.

It is advised to adjust:

the View Angle, until you see your whole study area in the map window,
the Vertical and Horizontal Rotation, until you see your area from a favourable position,
the View Point, until the 3D view is nicely positioned in the map window,
the Scale Height, to exaggerate height differences,
or other parameters as you wish.

Note:

The 3D view parameters are not independent. When you change one parameter, some others may automatically change as well. When you edit the values of the view point, horizontal rotation, vertical rotation or distance, the values of the location point and/or location height of the observer automatically change, and vice versa.

To exit the georeference 3D editor:

To close the georeference 3D editor and return to the map window, click the Exit editor button in the toolbar, choose Exit from the File menu, or double-click the control-menu box of the dialog box. Your 3D view is displayed in the map window. The parameters last used in the editor are stored in the georeference 3D.

As the map window now uses this georeference 3D, you can also add other vector maps to improve the 3D view. Of course, you can also add annotation.

To save the 3D view:

To save the 3D view in the map window, choose the Save View or the Save View As command from the File menu in the map window.

To permanently display a raster map with a georeference 3D, you can use the Apply 3D operation.