Types of 3D data

Surface

Solids

Grids

Surface

Surfaces are three-dimensional planar items, which have an area but no volume.

Creating a surface item

Surface items can be created in three ways. One way to do this is:

1. Select the LineString or closed MultiLineString item(s).
   
   
2. Use Extrude [Create-3D].
   
   
   
   
3. Supply a distance, or an expression that will be used to calculate the extrusion distance.
   
   To use an expression click the button drop-down and select Edit an Expression to display the Expression Builder dialog.
   

An alternative method for creating a surface is:

1. Select the Polygon item(s).
   
   
2. Use Triangulate [Create-3D] or the local command Convert to 3D Surface.
   
   
3. You can give the area a height by using the Properties of Surface dialog, Origin Z option.
   

 A further method for creating a surface is:

1. Select the LineString or closed MultiLineString item.
   
   
2. Click on one of the grab handles.
   
   Note: The grab handle position must be moved slightly before the next step is carried out.
   
   
3. Type in comma, comma and the new Z value (e.g. ,,50), then press Enter. The point on screen will be given this height, and, if viewed in a 3D window, the surface will appear curved.

Solids

Solids are three-dimensional solid items which have volume. For example, a rectangular building could be represented by a solid item.

Creating a solid item

To create a solid item:

1. Select the LineString or closed MultiLineString item.
   
   
2. Extrude the area using Extrude [Create-3D].
   
   
3. Supply a height to which these items will be extruded.

Grids

Grids are raster items where each pixel or cell has a colour value that corresponds to a numerical value. This numerical value can represent various different scenarios - for example, the number of people living in the area represented by the cell (population density); the reflected sunlight produced from a certain type of vegetation represented by the cell (seen in certain types of satellite images); or the height above sea level represented by the cell. This last option is the starting point for a type of Digital Terrain Model (DTM).

Grids are fully explained in What are Grid items?

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