This is a free opensource Loop subdivision plugin for Google Sketchup. Loop subdivision smooths hard edges to give a more rounded organic looking shape. This plugin has not been tested extensively, so please save any important Sketchup models before using this plugin on them.

To use:

1. Download the file below (loop_subdiv.rb) and save it in your Google Sketchup plugins directory. On Windows it will be somewhere like C:\Program Files\Google\Google Sketchup 7\Plugins.
2. Re-start Sketchup, there should now be an extra option "Loop subdivide smooth" in the tools menu
3. To use the plugin select your model and click "Loop subdivide smooth" in the tools menu.
4. A box will appear asking how many times you want to repeat the subdivision (1,2,3 or 4 times). More repeats gives a smoother model, but also takes longer, so try 1 or 2 first.
5. You can choose whether the subdivided object has softened and smoothed edges.
6. If you have a large model (with lots of faces) the smoothing will take a long time so be prepared to wait!
7. The smoothed model is added to a new layer(called Loop_subdiv_XXXX)
8. The original selection is deleted (but you can Undo the operation to get it back)

For the technical details see the Hoppes and co-workers paper: Piecewise Smooth Surface Reconstruction . This paper also describes how to do partial subdivision, using crease edges and darts, which are not yet implemented in this plugin.

Two other subdivision plugins on www.smustard.com use Catmull-Clark subdivision. There is no theoretical reason why Catmull-Clark subdivision should be better than Loop's subdivision, but Dale Martens' Subdivide and Smooth plugin below has extra features like crease edges and is probably faster and generally more polished:

• RickW's is free, but not opensource, and does not work on models with holes.
• The Subdivide and Smooth plugin is not opensource and costs $22, but from the screenshots and videos it looks very impressive, with lots of features and a smooth user interface.

You could also try exporting your Sketchup model to the Blender or Meshlab programs, which have lots of subdivision features.

Please feedback or leave comments about problems or suggestions for the plugin. This plugin is opensource, so I welcome any improvements in the code.

There are known issues with non-manifold meshes where adjacent faces do not share edges (try smoothing a captial E), I am looking for solutions. Also when smoothing components the face materials are lost in the smoothed object.