rickymaveety opened this issue on Dec 01, 2006 · 63 posts
Quest posted Sun, 03 December 2006 at 10:25 PM
I’m truly sorry Ricky I didn’t realize until now you were having any difficulties whatever modeling with Rhino. I offered help in the Bryce forum but no one indicated they needed it. I wrote it here specifically for your information and anyone else who can use it after reading this thread. I’m much more experienced using 3D Studio Max and Rhino isn’t really my forte as far as modeling programs go but it is my second choice. If you like, you may use this information and rewrite your tutorial but please don’t take yours down on account of this. It takes time to write an in-depth tutorial targeted at the masses with quality images and at present I have no such inclination.
I must add that there is one drawback to the technique I use when deriving curves from cross-sections and that is where the mesh is very detailed like around the face and when you try to derive a cross-section of the breast area of the figure, it will give curves but often they are opened curves and the loft feature in Rhino cannot handle both closed and opened curves in the same loft. It will handle either opened or closed curves but not both. Rhino will stop dead and tell you it cannot loft the object. So to get around this we must blend and join the curves to form one closed curve and this can be time consuming depending on how interrupted the cross-section is and how many cross-sections there are. It works well around the waist area because that part of the model is fairly contiguous and smooth.
Upon trying to execute a loft after selecting all your curves the loft tool tells you (just above the command line) to your dismay that it cannot do both closed and opened curves at the same time. So how do we know which curves are opened? What I do is create my own closed curve and run the loft again starting with the closed curve I created and then selecting the next curve from the model. If the loft takes, I cancel out from the loft options dialog now knowing that both these curves are closed. I then proceed to loft starting from the second curve, which I now know is closed and select the third curve and see if that loft takes. If it does, I cancel out again and continue the process until I find a curve which will not allow the loft to go forward. This curve then we know is opened and needs fixing. Fix that curve and continue on.
As an example, you determined which is the opened curve and you’ve isolated the curve from the rest of the mesh by hiding the mesh, if you see large gaps between the curve, these gaps can be easily handled using the Blend curves tool. But it’s not enough just to blend you also need to join all the ends to have them fuse into one curve. Blinding provides the missing piece but you need to join the ends.
Often you’ll not be able to visually detect a gap. To get around this you simply type in on the command line “CrvStart”, simply typing a “c” will bring up a list of commands which start with the letter “c” and you can select it from there. This will place a point where each segment starts letting you know where the breaks are in the selected curve (you can also use the “CrvEnd” command to find the end of a segment or use both commands). Use the window zoom tool as often as necessary to be able to view the gap allowing you to blend and join them together. The points will remain even after all the ends have been joined giving the illusion that you still have breaks but this is a fallacy. All you need do is select the point/points and delete them.
If you are interested and these procedures are not clear to you, then let me know. I will churn up a fast and dirty mini tut for you.