T-Splines in Rhino: preparing NURBS surfaces in Rhino for T-Splines

When preparing T-Splines optimal surfaces in Rhino, I use Rebuild command to have enough control points on the surfaces. In this tutorial (https://youtu.be/JZ_bA_4XTpg), it teaches me how to prepare Rhino's NURBS surfaces to be used in T-Splines.

Plan surfaces in Rhino are all degree 3. It means the minimum point count in the U or V direction is 4. When the surface with 4 points in U or V direction is converted in T-Splines, I will get one single face. But if I increase the point count to 5 in U or V direction, I will get 2 in both directions or 4 faces total.

So it is easier for me to think in terms of how many faces are in my model when I convert them into T-Splines. If I want X faces in U or V direction in my T-Splines model, then I rebuild my NURBS surface to X plus 3 control points in that direction.

Rhino: Fillet and FilletSrf

In Rhino,  using Fillet and FilletSrf on the same edge of a surface model will give you different results.

For example, if I create a cube and use Fillet to add a fillet to an edge, the edge turns into a filleted surface. When I click on this surface, it will be highlighted together with other surfaces of the same cube. It will be like this:

Whereas, if I use Fillet to add a fillet to the same edge of the cube, I click on this surface, it will be highlighted alone. Beside the edge is filleted alone and the adjacent surfaces will not be affected. That also means the newly filleted surface is not part of the surfaces grouped in the cube any more. I may need to regrouped it with other surfaces. It will look like this:

 



OnShape - the promise of CAD in the future is here now

I signed up a free account at OnShape and tried it today. I would say it is a promising CAD solution that could shape the future of CAD. By using OnShape, a user can experience what the things will come in CAD industry.

OnShape is a CAD system built on the cloud. Your internet browser is turned into a platform on which the CAD programs like OnShape can run. Whereas OnShape is more than a CAD program and that is why I call it a system. It comprises not just the CAD program, but the online collaboration tool, online data storage, and mobile app. Literally it is a Software as a Service system.

For starters: If you are not familiar with SaaS concept, you can look at the example of  salesforce.com as the harbinger of SaaS, or later Adobe’s Creative Cloud. The software is built on an online platform and is subscription-based without upfront purchase of the entire software. So a user of the software does not own a copy of the software and only pay the subscription.

As in the case of OnShape and other SaaS programs, the programs are constantly updated without version installation and/or upgrades. That is why OnShape is what the CAD programs look like in the future.

The 2 most distinctive features to me in OnShape are the direct editing function and online realtime collaboration. Given OnShape is a feature-based parametric modeling program, it allows a user to break the ranks of feature tree to directly alter the parameters on a feature and to determine the scope of propagating changes after the alteration. As far as online collaboration, OnShape’s development team claims that multiple users can work on different portions of the same part or assembly simultaneously.

The modeling tool in OnShape at this moment is heavily depending on 2D sketches and solid modeling. As an industrial designer, I would expect that more Spline curve and NURBS surfacing modeling tools will be added later to strengthen form creation capability inside OnShape. Or even further, it will be ideal that the subdivision modeling be also available in the future.

I have not tried out every major feature in OnShape but if all claims made by its developers are true, OnShpe will be an amazing and ground breaking development in CAD industry.
 

Best Design Trend Spotter Ever Online

The best online place for me to find inspiration and reference on design trends in form creation, material, color and finish is: AWOL trends, http://awoltrends.com/

Industrial designer Andy Logan set up his shop AWOL in southern California and has a company website at http://awolcompany.com/

He and the CMF (Color/Material/Finish) consultant Reiko Abo Morrison at the firm has done tremendous homework to spot and articulate the trends. They detail the findings in the page for a specific trend and then support the reasoning with plentiful examples gathered from all kinds of resource.   The collection of examples they assemble can come from visual art, architecture, interior design, fashion, graphics, and of course product design.

This design trend site is my go-to place if my project comes up and I am required to do research on design styles and trends. It is highly recommended for any designer or product development team member who want to scout for latest trends related to product design.

 

T-Spline: four types of vertices

In T-splines there are four types of vertices (or control points): T-points, star points, tangency handles, and ordinary control points.

·        T-points: end lines of detail: T-points can be created by many commands, such as insert edge, insert point, subdivide face, merging, and welding, and are used to constrain detail to part of the surface. T-points constrain detail to the edges of the T-spline surface.

·        Star points: create non-rectangular surfaces: Star points allow a T-spline to be non-rectangular. Star points can be generated by commands such as extrude, delete face, and merge. It is more difficult to control the shape of a T-spline at star points, so they should only be used where necessary.

·        When a T-spline is exported to NURBS, it will split into separate surfaces at each star point. the NURBS is split into rectangular patches at each star point. Additional isocurves are added to the NURBS to maintain surface continuity.

·        Using T-points and star points in a model: Using star points and T-points correctly is very important to modeling with T-splines effectively. T-points are used for adding local detail by isolating control to one area on the surface. Star points are used when the model require a non-rectangular topology like surfaces with holes (non-trimmed), closed surfaces, “Y” branches, surfaces with legs, etc.

·        Influence region of a star point (two faces deep). There cannot be any T-points in this area when the model is standardized.

T-Spline: Anatomy of a T-spline surface

Anatomy of a T-spline surface

·        T-spline surfaces consist of faces, edges, and vertices, and can be displayed as a boxy mesh or as a smooth surface.

·        T-spline surfaces can contain holes, creases, be open or closed, have local detail, be rectangular or non-rectangular, and contain triangles or n-sided faces, while being one unified surface.

·        All T-spline surfaces in Rhino are degree 3.

Rhino 3D - Insert Kink

InsertKink

InsertKink is a special commaned in Rhino which adds kinks in a curve. The curve can be split into multiple joined curves.

 

Steps:

Select the curve.

Pick locations where you want to insert a kink .

Press Enter to end the command.

The curve is split into multiple joined curves.

Point Editing > Insert Kink

Edit > Control Points > Insert Kink

 

Another unique command related to insertkink is non-periodic surface.

non-periodic surface is a closed surface with a kink at the start/end of the surface. Deforming non-periodic surfaces near the start of the surface may result in kinks. Non-periodic surfaces are automatically created when the input curves are non-periodic.

 MakeNonPeriodic

Makes a periodic curve or surface non-periodic.

Steps:

Select the objects.

The MakeNonPeriodic command changes a periodic surface or curve into a non-periodic surface or curve. Non-periodic surfaces and curves can develop kinks when deformed.

Surface Tools > Make Surface Non-Periodic (Right click)

Curve Tools > Make Non-Periodic (Right click)

 
 

Rhino: Power of control points on a surface

In Rhino, by turning on control points on a surface, I can manipulate the surface by dragging the selected points.

To harness the control points better, I have to use Transform/Set Points command to align control points by choosing options such as Set Z (make all control points with the same z value) and Align to World.

Use ESC to turn off control points.

Rhino: Difference between _Curve and _InterpCrv

The InterpCrv command draws a curve through selected locations in space. It is called the interpolated curve in Rhino as it is called spline in many CAD programs.
(http://docs.mcneel.com/rhino/5/help/en-us/commands/interpcrv.htm)

The Curve command draws a curve from control points.

Usually I would use InterpCrv to create spline curve because this is the same method I use often in Solidworks to create spline curve.