Hi Mazinga, it looks like you are making some great progress here!
The front part of your canopy will create some problems for filleting in this case - since the front part comes down to be smooth with the fuselage, that would mean that fillets along the sides would pinch down to nothing as they approached that point. Currently MoI's filleter does not handle this kind of "totally pinched down" situation very well - it's a much more difficult area of calculation.
In general when you want to apply fillets to something it is better to make the pieces touch at a sharp angle throughout the entire length of the edge and let the filleter do all the work of rounding off everything.
In some situations like this that kind of means giving up some direct control over the shape in that particular area. Like in this case instead of drawing the profile of the fuselage exactly how you want it to finally be, you would draw it more like this (I shortened your canopy to make this a little more simple for this example):
That gives up some direct "drawn" control over the base of the profile, you need to imagine what it will look like when the fillet is in place and leave it up to the filleter to finish the bottom portion of it.
Also notice that the canopy shape that I have drawn here punches all the way through the fuselage, I have not tried to draw it such that it ends directly hugging the fuselage. This is another general tip - when different shapes are merging, often times it can be better to let surface intersection curves be created either through Booleans or Trim, rather than trying to build a second surface that hugs exactly along an existing surface. You can do that if you already have a hole or something in the first surface that you are trying to build off of, but not so much when you are modeling pieces separately and combining them with fillets.
Next I used Trim to cut these 2 pieces and keep the outer regions. You can use Booleans too, but Booleans tend to be used more often with solids instead of open surfaces. Booleans tend to incorporate automatic discarding of different pieces and when you only have open surfaces involved it may not always discard the piece that you expect. With Trim you are in full control over which pieces to keep or discard. After doing a Trim you will usually follow it with Join to glue the pieces together at their common edge.
So I selected these 2 pieces, ran Edit / Trim, then did a Right-click to do a "mutual trim" (trim each of these with the other), then switched mode to Keep and picked on the outside 2 pieces to keep them and discard the rest. Then after joining that left me with this:
The other benefit of punching the pieces through each other and then trimming them is that this topology is now much cleaner for filleting, since the bottom of the canopy is all one smooth edge where it meets the fuselage instead of having a more rectangular sharp corner. Sharp corners will create additional geometry (and are just more generally complex) when filleting. So prepping things with a smooth edge can also help for getting a successful fillet.
Then with this topology I can apply a fillet to the bottom:
I think that this general idea of purposely pushing pieces through each other and then doing booleans is probably one of the pretty foreign concepts as compared to a sub-d workflow, since you are going to be connecting things directly together more often in sub-d.
> Being relatively new to NURBS, I have struggled somewhat with workflow issues that are
> rarely addressed by Rhino tutorials I've seen. If anyone knows of a good resource for
> "rules of thumb" when modeling with NURBS, please post a link!
Don't forget to go over the MoI tutorials here:
http://moi3d.com/1.0/docs/tutorials.htm - I tried to make these go over a lot of the basic NURBS type workflow there.
> For example, I understand that it is desirable to maintain valid solids as one models,
> but am not sure how far to go with Boolean unions--whether it is better to have many
> discrete solids or fewer solids and more unions.
It's difficult to give any one single rule, but especially if you want to fillet then a big goal is to have a simple topology with fewer edges and corners in it.
Many of the construction tools will tend to create a rectangular topology, just like you created for your canopy - but this is not always the proper topology for how the pieces should be finally connected together for filleting. So that's why it can help to build things punched through each other and then trimmed - cleaner final topology. There is a kind of similar situation when trying to construct an object that has a complex detailed edge in it - instead of constructing directly off of the detailed edge you generally want to build a larger rectangular sheet using something like Sweep or Loft, then trim that by the detailed edge to create your final shape.
So again it is incorporating "building extended then trimming things back" that is probably the single biggest difference in workflow as compared to subd.
> Also, memory use has been rocketing as my file gets more detailed,
> and I only have 512MB at my disposal.
Yeah, that is quite a bit on the low side, if you want to do much beyond basic shapes you can go over that fairly easily. Right now MoI generates pretty dense display meshes so that you get a nice display. You can turn this down by going to Options / View / Meshing parameters, and set "Mesh angle" to 20, and uncheck Add detail to inflections. That will cause a more coarse and jagged-looking display but it will also take up less memory. I'd really suggest upgrading your system memory though.
> Also, what is the best way to model a cockpit or cabin that you want to
> be visible through windows? Just subtract the desired volume or shell some part?
Generally I would think that these would be separate objects. I guess you would start by kind of building a new solid for the cockpit/cabin area and then create a panel - again create it larger and then intersect it with the cockpit to slice it down.
> Are windows modeled as solids, that is with some thickness?
Hmmm, not sure about this - maybe not if you're not going to do any closeups of them.
> Do folks usually subd the MoI output?
Sometimes, but I think most of the times not.
> Will subdivision tear the mesh?
No - not if it has been created as a connected skin with surfaces joined to each other at their common edges. MoI does some work during its meshing to ensure that the resulting mesh has common vertex locations along these shared edges, so if "Weld vertices along edges" is turned on at export time, you will have a completely connected mesh.
But the topology of this mesh is not always very suitable for subdivision. Probably your best bet would be to export as Quads & Triangles (n-gons probably won't be suitable since they can have concave shapes), and also use "Divide larger than" to dice up the mesh into more regular sized pieces - see here:
http://moi3d.com/1.0/docs/moi_command_reference10.htm#meshdialog under the "Divide larger than" section for an example of forcing dicing up.
Hope this helps!
- Michael
