Model the threads on a bottle in Softimage
Create a single polygon
Once broken down to individual steps the procedure for creating the thread for the bottle, or any thread for that matter, is essentially a no-brainer. Rather than adding thread onto the existing geometry, you’ll create the tread as a separate piece and then weld it together with original object. The first step is to create a flat polygon with the same length as the circumference of the neck of bottle and with the preferred height of one revolution.
circumference = π * diameter
Knowing the diameter of circle you can calculate the circumference using the formula: circumference = π * diameter (who knew those dull math lessons during compulsory-school would actually pay of one day.) Once the flat polygon is in place you’ll need to split it diagonally from top left to bottom right. The next step is to divide the thread (the currently flat polygon) to match the number of vertices on the bottle. Then simply duplicate the object as many times as want turns on the thread.
Merge the objects together to create a single mesh and bend it 360 degrees to form a cylinder. Weld the seam and delete the perpendicular edges. Select the edge loop forming the tread, duplicate it and then delete the original loop. Select the new polygon loop and extrude it to create the tread. Merge the two objects together and you’re done. Don’t worry if you missed a part of the procedure, the full video capture can be found on this issues CD.
The project files used in this tutorial can be found at: http://www.redi-vivus.com/Caffeineabuse/Bottle_Threads.zip