The Specifier is tool to specify a physical design.
A specification is a produceable description of something.
Its completeness is determined by the user of that specification.
The specification of a physical design facilitates its production
both at prototype-test stage, when it is used by a fabricator or assembler,
and at production stage, when it used by a factory.

Specialisation:  land-vehicle design

A physical design is a designed, solid 3D object.
We validate the effectiveness of the Specifier by
using it in the specification process of a land-vehicle design.
A land-vehicle has some symmetry properties,
a substantial size (much larger than a PC screen),
involves the use of wheels and is used in a variety of conditions.
Its PC-based specification is necessary,
because it has to be produced accurately,
with operational parameters such as balance, rigidity and handling,
being directly effected by the specification of the design.

Key features

1. The Specifier uses a hexagonal grid instead of a cartesian-grid.
   This is a better way to select points in a 2-D plane and points in 3-space and hence, also angles.
   Rotations in 2-space and 3-space are a lot easier to describe, and to implement.
2. It has a very simple user-interface based on InterUnit-UI.

The Specifier's user-interface

1. A designer can load photographs of a real object into the app,
   (with a description of the camera parameters used in taking those photographs).
2. Identify (in terms of 2D point descriptions)
   the components in the structure of the object in the photograph.
3. For each component, they can describe its 3D orientation and size,
   based on physical measurements.
   This creates a model of the component,
   describing its dimensions, orientation and placement,
   in the model of the containing object.
4. They can add off-the-shelf, commonly used construction components to the model,
   and specify connectors to join components.

PC implementation

The Specifier implements a custom rendering and visualisation engine for these models.
This engine implements perspective correct display-screen mapping of 3D objects.
It models a single camera with location, orientation and film-size and focal-length controls.
It maps all planar 3D-elements using direct, 4-point 2D-plane mapping.
Curved planes in 3D are modelled as piece-wise planar flat planes.
It does not implement any lighting controls
and uses colours and textures to indicate material properties.

A proof of concept demo

The first version of The Specifier will showcase
the specification of our bicycle-trailer design.
We plan to release this demo on Friday, Jan 02.