A while back I posted a question about methods in creating nurbs surfaces like a rectangle for example and now for my senior architectural design project I need to take it one step further. Without any pictures it might be hard to describe what I'm looking to do but when I get home I will post pictures of my prelim model. basically what im doing it creating a planar landscape with precision "slits" throughout to replicate icelandic greenroof houses with a modern twist. I have a nurbs surface created and the control points activated but now what i want to do it is actually use these lines to slit the nurbs surface creating new control points that i can use to morph the nurbs surface. Ive tried boolean operations but I cant seem to get the line to effectively slice the plane. I'm horrible at explaining things so I hope someone can understand and help me lol. Thanks everyone.

When you do a boolean operation, there are no new surface points added, instead "trimming curves" get added to the surface. There is some explanation of that here which may help illustrate it better.

Right now MoI is not generally focused so much on surface control point manipulation... Although there is some basic functionality to do it, there isn't currently a way in MoI to insert new points right in the middle of the surface.

But there are a variety of other strategies that can be used instead - the initial surface can be created with control points in the areas you need right from the beginning, using Extrude with the "Set path" option (see http://moi3d.com/forum/index.php?webtag=MOI&msg=817.4 for an example).

Or a more typical method would be to create several curves that have the shape you are looking for and use a surface creation command like Loft or Sweep to build the surface you want directly, instead of trying to squish some other surface into the surface you want.

Also it tends to be more common to add in smaller details by booleaning in a small assembly in the area you want to add detail in, rather than trying to manipulate one single big surface to have detail in a small area. You can use the Fillet command to round off the corners of where your new module meets the larger surface to give it a smooth appearance.


It is hard to give you much more specific advice, because I just can't quite tell what type of thing you are trying to build from your current description and screenshot, sorry! If you can post a sketch or something that would explain it more, that would be a big help. I especially don't understand how you want the slits on the surface to be arranged.

You can't generally cut a surface with a single line that is totally inside the surface, to boolean an object with a line, the line needs to divide the surface into 2 pieces.

If you want to cut a small opening into a surface, to use a boolean you would normally create a closed curve to use as the cutting object. It can be squished down to be pretty thin and narrow, but it still should form a closed loop instead of a completely collapsed slit like a single line.

- Michael

hey michael thanks for all the tips and info they will definately help in the future but i think i will need to use rhino for this maybe. i have attached two pictures of my studio study model which can better describe what im looking to do. if these pictures can spark something please you or someone else let me know. thanks!

Hi airdog - that gives me a lot better idea. I'll see if I can come up with a couple of examples for some different approaches.

One method might be to draw some curves and then build your model by sweeping along those curves to build things up in strips.

Or if you want to have one single surface and trim holes in that, you will probably make a closed profile in the elevation/front view, and then use that as the cutting object to trim, instead of trying to have trimming lines placed in the top view.

- Michael

It's funny because I just see something similar but with another prog :)
http://www.sketchucation.com/forums/scf/viewtopic.php?f=20&t=8067&p=47511#p47511

Hi airdog, this is the method that I would recommend for the "trim a single surface" approach.

If you are starting with a surface that has a bump in it:



Switch an elevation view, like in this case the front view. Then draw a closed profile curve. In this case I drew the curve in 2 pieces, kind of following along the contour of the surface, then I selected the 2 pieces and used Edit/Join to glue them together, the result looks like this:



Now to trim the hole, make just the surface selected, then run Edit/Trim. Then MoI will show a prompt in the upper-right corner that says "Select cutting objects", at this point select the curve, it should look like this now:



Push "Done" or right-click to tell MoI that you are finished picking cutting objects. Now the surface will get sliced up by the projection of the curve:



The prompt will now read "Select pieces to remove or push Done to keep all". You can now select a fragment to remove, like this:



And then click Done or right-click in the viewport to tell MoI you are finished picking pieces to remove, and this is the final result:



So I hope that might work as a way to do the trimming that you were asking about originally.

A bit later on today I will see if I can give a different example about building your thing in strips instead of from a single lumpy surface.

- Michael

Hi airdog, here is a kind of different method for building in strips.

What I did is I started by drawing some curves in the front view:



Here is what these curves look like in the 3D view, they are all stacked up:



Then slide them over to separate them, keeping 2 together in the middle:



Then select 2 of them:



And run Construct / Loft to create a surface between them:



Then select the other 2 and repeat:



This is the result:




I just put this together really quickly, I think you would want to probably be more careful so that all the pieces lined up on the right side for the middle pair, so that the 2 strips would touch exactly in that common area. Probably one way to do that would be to have the curves made up of more than one piece, and have an identical piece along that right side portion.

Some other ideas are instead of using 2 curves for a strip, you could gain some more control over the shaping by using additional curves like 3 or 4 curves for a single strip, and then you can get some more control over the shaping of the strip by having some variations in the shapes of those inside curves. Also another approach would be to draw some crossing pieces and then build the strips using sweep with those pairs as the sweep rails.

I hope this might be useful,

- Michael

Opens up some great visual potentials for me. thanks
Hexagon gets further and further away from my needs!

Cool Brian, it looks like you have got the idea there!

- Michael

thanks for all of the ideas guys!