SubD Precision Tools

Rhino SubD
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The Sub-D tools inside of Rhino development is quite interesting, but I believe it will take a while before we will see a full feature set. The Sub-D modeling workflow is quite good for creating smooth organic shapes.

A lot of people were excited about T-Splines, and Clayoo offers a lot of the same functionality as well. However if you look at programs like Modo and Blender that excel in Sub-D modeling it’s easy to realize that it’s going to take a while to get functionality that is even close. The main drawback of Modo and Blender is that they lack the accuracy of a CAD program.

What if there’s a focus on adding accuracy to an existing Sub-D mesh. Both Modo and Blender can export quad based OBJ meshes and if we can import these meshes into rhino and add precision and convert to NURBS, that could be a relatively quick path to real functionality inside of Rhino.

This workflow would allow a user to use the strength of the Modo and Blender modeling tools to “rough in” the shape and get it really close and great looking. Once this step of the process is done the Modo/Blender OBJ is brought into Rhino for final tweaking.

I can think of things like matching a circular looking proflile to a round NURBS object. Snapping part of the mesh to a super smooth Nurbs surface to create a very high quality Mesh, moving certain aspects of the mesh with numerical input to create exact distances, etc.

This is not to say that McNeel shouldn’t move forward with a full set of Sub-D modeling tools inside of Rhino, but I can see this being very useful, less time consuming and adding useful functionality relatively quickly.

The cost of entry for Blender is free and the cost of entry for Modo on subscription is $59/month. I’m sure some people will make the argument that they don’t want to learn a new tool, but let’s face it all the new Sub-D modeling tools introduced inside Rhino will also need to be learned and the Sub-D modeling techniques learned in Modo/Blender will carry over to Rhino tools as they get added.

My 2 cents

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You already can do the Blender -> Rhino bit, obviously. And mind you that with Blender you can also give numerical input when modifying geometry, which should give you quite a bit of control already before you push your object to Rhino.

What do you understand under adding accuracy to an existing subd mesh? What does it mean?

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Hi Nathan,

First of all I don’t have the wip installed and haven’t played with the Rhino SubD commands, but I still have V5 with T-Splines. So my experience is based on T-Splines tools for now.

First question, can we smooth a quad based OBJ in Rhino similar to the Tab key in T-Splines/Modo? If so, in most cases the mesh would look good, but is not accurate. What I mean by that is just because something looks round doesn’t mean it is round. Or just because something looks like its 50mm from the front plane doesn’t mean it actually is 50mm from the front plane. It is quite easy to move a few control points too much and loose roundness, symmetry or location.

One of the things we can do with T-Splines in Rhino is position vertices with precision/accuracy. I understand there is numerical input in Blender and Modo but it doesn’t really mean anything. If I move points in Modo say a few times, there’s no easy way to find out where those items are. Say flat faces need to be spaced out an exact amount of 100mm evenly across an axis. If the vertices are a little messed up, we can grab all of them, flatten them and position them 50mm from the axis with the gumball using T-Splines.

I installed Modo and talked to their support to see if I could use it instead of T-Splines. All their answers are that Modo is for graphical applications and you need to use CAD if precision/accuracy is required.

Hence my suggestion in this post. I can model something quickly in Modo and get it close, bring it into T-Splines and move faces into exact locations using the gumball or matching to NURBS geometry.

Does that make sense?