The Specifier is an MCAD tool for specifying structural-assemblies.
A structural-assembly is specified in terms of it's component parts and construction processes for connecting these parts. These processes can be implemented in an associated production facility called a Unit-construction-hub, also specified using The Specifier.
Existing MCAD tools
The following is a review of MCAD tools commonly used by small and medium scale enterprises.
MCAD tools represent solid objects using parametric descriptions created using a "geometry-modeler".
To visualise these solid objects on a 2D screen, they are represented by their 3D boundary surfaces (BREP).
The ISO has standardised a format for BREPs and all tools support this format for interchange.
For most industrial design projects, a 3D surface does not need to be edited directly.
Common shapes are used and ther properties are controlled using the app.
Sometimes, as in the case of specialised exterior sheet-metal design for an automobile,
specialised tools are used to directly specify 3D surfaces.
In addition head-mounted-displays, which offer a full 3D viewing experience are used for visualisation.
Motion sensing sensors can be used to input shapes using hand movements.
Hand-gesture based 3D surface input is a new direction that tools are starting to explore.
Direct 3D surface design is still a process with a learning curve and its use is not very prevalent.
Clay models continue to be used to create 3D surface designs, such as for automobile design.
From a designer's standpoint, MCAD tools are characterised by their geometry kernel.
Examples of geometry kernels, currently in use, are Parasolid (Siemens), 3D ACIS Modeller (Spatial), ShapeManager (Autodesk), Granite (PTC), Convergence Geometric Modeller (Dassault), openNURBS (Rhino3D) and C3D (C3DLabs).
The most commonly used tool
Cloud-based collaboration enabled tools
Established alternative tools
Newer niche tools
MCAD related articles
MCAD domain review The domain of MCAD has evolved since the first tools for 3D modeling and visualisation were introduced about 30 years ago. 2D CAD had been around for a long time. MCAD started with 3D.
3D-object visualisation on a PC display (review)
Mechanical CAD tools require a mechanism for visualising 3D objects on a 2D display.
We present a brief review of the underlying technology involved and how major MCAD tools use that technology.
Design and design-specification
We focus on structural design and the design of metal-based structures.
The link below is a description of our design specification process for a structural-assembly.
The Hexagonal-grid as a CAD tool development aid
A Hexagonal grid is like an extended virtual protractor
(the instrument used to measure angles).
It can be used to choose or specify angles and curves in a mechanical CAD process.
What is design-specification?
There are 2 aspects to the specification of a land-vehicle design.
- A structural specification.
A static description of the built up structure of a design.
It includes a specification of each part in a design,
how the parts connect with each other,
and a structural model of the user (if applicable).
- A construction-process specification.
Specifies the construction-process of a design.
How each component in the design is contructed
and how the components are put together to produce the design.
This is useful for an assembler or a fabricator.
What is specification visualisation?
A (design-specification) Visualiser implements perspective-correct display-screen mapping of modelled 3D objects.
Our visualiser models a camera with a location and orientation,
and a single light source, at the same orientation and location as the camera.
We represent a 3D object as its outer surface,
a lattice of 3D planar segments.
We map these 3D planar segments onto a 2D screen using 4-point plane-mapping.
A curved plane (in 3D) is modelled as a lattice of flat planes.
Our visualiser uses only the device's (2D) drawing engine,
and targets a visualisation time of 100ms/frame
for a bicycle-model at 4K resolution on an Snapdragon 8 Gen 5 SOC class device.
Construction-process specification in the Specifier (planned) We plan to produce a construction-processes specification component after the structural specification component. The designer will identify several construction states in the construction process. Each construction state will be a physical model of the relative placement of the components and tools in the process. The designer will indicate transitions between construction states. The construction-process specifier will use these construction states and transitions between them to create an interpolated sequence of models to be visualised. This sequence will be visualised using the Visualiser with some animation controls.
Photograph assisted specification in the Specifier (planned) After the mouse and keyboard specification interface, we plan to produce an additional interface to improve structural specification input efficiency. This interface will work as follows:
- A designer loads photographs of a real object into the app (with a description of the approximate camera parameters used in taking those photographs).
- Identifies (in terms of 2D point descriptions) the components in the structure of the object in the photograph.
- For each component, they describe its 3D orientation and size, based on physical measurements.