Introduction to 3-D

As we seek to improve our understanding of the real world through remotely sensed data, data modelling or field surveying, one key dimension of the landscape that we have to account for is the third dimension.

The things we consider in our 3-D worlds can be the terrain, a valley, gully, mountain or even a flat plain, they can also be natural features on the terrain, such as vegetation or man made features such as buildings, bridges, structures, vehicles and even people.

At this point we need to be precise about what we mean by 3-D. Here and in may other texts we refer to data relating to terrain , building blocks or other objects that we model, such as car, tree etc as 3D data. However really these are only the surface expression of the object and not internal data about the object.

So for example when we display a 3D terrain such as a mountain it is in reality a wire frame model and if we ‘drill’ into it we will not find anything inside it. The model is simply a drape over a wire frame.

So strictly speaking we really should call it a 2.5D model, but that sounds awkward and isn’t commonly used so we always revert to calling this sort of data 3D.

The collection of data with 3rd dimension has traditional been from contour maps, aerial photos and more recently Satellite images.

The ground, or terrain is modelled and a wire mesh or contour model is produced, with each cell of the mesh or each contour being given a height above sea level.

More recently we have the ability through devices such as a LiDAR scanner, either on an aircraft, helicopter or car, rapidly and with a great degree of accuracy to collect 3D data about the ground and all objects on it.

Whilst we have been able to collect vast amounts of 3D data they are often held in a complex form, requiring an advanced computer to manage it and when displayed it doesn’t help us other than looking like a nice picture.

However with advances in computer processing, software development and in data collection and transfer we now see the emergence of tools that enable us to create realistic 3D worlds and more importantly interact with them.

In this practical you will see some of these tools, as provided by Google along with some other more specialised tool for the LiDAR practical. Using both these tool sets you will create a 3D world of Luton Airport, populate it with other 3D models and interact with it.