Significant enhancements to NURBS modeller
Rhino 1.1 from Robert McNeel and Associates
Despite being named as an incremental upgrade, the new 1.1 version of Rhino the Windows based NURBS surface modeller from Robert McNeel & Associates offers significant enhancements to the original release.
As a conceptual and free form modelling tool, ease of use is vital and there are plenty of tweaks to improve existing tools as well as new interface functionality.
Most important amongst a wide range of new modelling tools is the NetworkSrf command that creates a new surface from a curve network even if the curves do not exactly touch by using the new Gazelle technology of high speed non linear optimisation.
Rhino does not set out to be a comprehensive engineering modeller but rather a companion product for rapid concept work and creation of complex surfaces sufficiently accurate for integrating into the final design data.
The range of supported file formats has been extended and despite the comprehensive modelling capabilities Rhino will still give responsive performance with a minimum 32MB RAM under Windows 95, 98 or NT.
Rhino sports a full CAD interface with toolbars and command line interface, layers and coordinate input for accuracy when required.
Multiple views can be displayed simultaneously and the elevator mode allows two axis coordinates to be specified in one view and the third in an orthogonal view.
The input elevation can be set to minimise the need to create numerous construction planes.
Usefully a construction plane can be created perpendicular to a curve.
Behaviour of the middle mouse button can be set to pop up a list of recently used commands or a customisable toolbar.
Models can be generated by manipulating geometric primitives, by creating curves that can be extruded, swept or lofted into surfaces or from imported geometry.
Despite the capability to integrate multiple data types, true model quality is achieved by using NURBS and many operations work on NURBS objects only and not imported meshes so the SketchOnMesh command can be used to generate NURBS data from imported meshes.
Multiple objects can be combined simultaneously in Boolean operations.
Control points can be toggled on or off for selected objects.
When active, control points can be dynamically edited to manipulate surfaces.
In fact deformable planes can be generated with a user defined number of control points to allow subsequent editing.
Singly curved surfaces can be developed into a flat surface on the current layer and construction plane.
The Gaussian curvature analysis tool can be used to identify developable surfaces as Gaussian curvature is zero at every point on a surface that is linear in one direction.
Examples of this type of shape are cylinders, cones, and some steel ship hulls.
This UnrollSrf command is not intended therefore for bending and unfolding sheet metal or developing fabric patterns.
Marine engineering applications are also provided with tools to generate hydrostatic values for surfaces.
Although significant further capabilities will be built on the new Gazelle technology in future versions, it already offers significant benefits.
In addition to allowing the creation of high quality NURBS surfaces from non touching curves, if the base curves do not meet the edges of adjoining surfaces smoothly, G2 surface continuity can still be achieved.
Gazelle also creates less complex surfaces and is generally faster than conventional calculation methods.
A range of surface analysis tools are available.
For moulded components the draft angle analysis is invaluable as complex organic forms can be difficult to assess.
A colour contour plot is displayed indicating the angle between the surface normal and the current construction plane.
If a staggered split line is to be used multiple plots can be generated independently.
The quality of surfaces can also be assessed by displaying an environment bitmap displyed on the surface or a zebra stripe pattern that indicates surface defects and tangency by flow or misalignment of the stripes.
Curvature analysis includes Gaussian plots, max radius that helps identify flat spots and minimum radius to identify where curvature may be tighter thasn an intended milling cutter.
In all the analysis views a turntable command gives a useful dynamic view of the surfaces rotating.
Although Rhino is not intended as a full drafting application, selected 3D objects can be projected into a 2D drawing.
A single command generates three orthographic and an isometric view on the active construction plane including hidden line and layer placement options.
A range of annotation and dimensioning tools are now available and are supported in IGES, DWG and DXF exports.
Autocad 2000 file types are supported and objects can be exported in ACIS and Parasolid formats.
VRML exports now include object and background colours.
STL meshes can be imported for validation or even fixing surface defects and support is available for MicroScribe and Space Arm 3D digitisers.
Modelling can be conducted in wireframe or shaded modes with the model in white.
Objects can be individually coloured or use layer properties to structure the model.
This can be slow on the first render as a render mesh is generated from the NURBS objects.
By default this is saved with the geometry but a small save option allows a more compact file to be generated without render or analysis meshes if required.
OpenGL shading and render previews can also be displayed, utilising OpenGL hardware acceleration when it is available.
In addition to the integrated Rhino render engine, file export and material assignment tools are provided for the free external POV-Ray 3.1 raytracing application and the supplied Blue Moon Rendering Tools.
Rhino offers extensive modelling, free form surface creation and visualisation tools with exccellent data compatibility and accuracy for use in downstream engineering applications.
The learning curve is short and an international support network has been established to offer help 24 hours a day, seven days a week.
All this is available from Softcover for £499.