Shapefiles are comprised of three files: a *.shp file that contains the shape data; a *.shx index file linking the shapes; and a *.dbf file that contains additional data.
The values that are used are completely arbitrary in the sense that they may be GPS coordinates, meters from a reference point, or even furlongs, if that’s the choice of whomever made the shapefiles.
When using the plugin, select one of these files and you’ll be presented with something similar to the screenshot below:

- The first line is a computed name for the import using the date-time stamp.
- The second tells how many polyitems (shapes) are in the files.
- The X/Y max/min data provides the bounding box of the data selected. Anything outside what you provide will be ignored on the input.
- Numbers are assumed to be in inches; the scale value can be used to scale the values on input (or the model can be scaled after input)
- The height is a default value that will be used if none are selected from the database.
- If the database is used, it is denoted in this field.
- If it is desired to display the bounding box on import, select this value as “YES.”
- If you know that the shapefile data is in GPS coordinates, select the geolocate option to try and locate the model on import.
If using the database values, you will get a subsequent popup:

If this example, there are no height values to be useful. However, if there were, selecting the field for the height of the building, as well as the height of the base (if available), will use the various values from the database. The names of each building created will be tagged with the name field from the database (if one exists).
If no height values are available, you can select Display 2D instead.
I hope this helps … let me know what I need to clarify for you and I will try to do so.