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  • Software:Blender 2.72  ·
  • Difficulty:Advanced

Rules of the Exercise

  • 1
    Model a corner on a sphere without pinching.
  • 2
    All-quad geometry; no triangles.
  • 3
    Each image showcases the roundness and lack of pinching on the corner when subsurface-smoothed (from different angles).

Applying what you've learned

Learning how tools work and understanding them is one thing. Actually applying that understanding to a real project is another thing. There's a LOT of hard surface polygon modeling in the Sci-Fi Helmet course. And one of the trickier modeling tasks is a hard-edged corner on a spherical surface.

The challenge

In this exercise your challenge is to fix the pinched corner on the downloadable model. You can either start from scratch to fix the pinching with new topology, or manipulate the geometry that's already there.


  • Download and open the blend file (E2_eliminate-pinching-from-interior-corner_start.blend.zip) from the Downloads tab.
  • Analyze the pinched corner and smooth it out so it's appropriately round.
  • Take 3 screenshots from different angles to showcase the fixed corner and another wire-framed version. Post each screenshot into the respective box of the PSD Template (exerciseTemplate_eliminate-pinching-from-interior-corners.psd.zip).
  • Submit the completed template as a .JPG image.
  • Don't forget to grade other submissions!


There are multiple solutions to solve this kind of pinching. The solution in the example above is simpler to achieve than it is difficult, and uses the existing geometry.