Dead Space 2 Marker Redux

This is a re-upload of a remix originally posted on my Thingiverse: https://www.thingiverse.com/thing:3497406

Summary

Dead Space markers are made up of many non-planar quads. The triangulation required for 3d printing results in some nasty undesirable, and inconsistent creases.

For this remix the model topology has been manually un-triangulated and cleaned up to allow for high resolution subdivision before re-triangulating, such as when saving as an STL.

Original mesh on the left, final smooth mesh on the right

Included you'll find:

• marker_cleanup.obj : Untriangulated Marker with hard edges marked for subdivision and no subdivisions applied (1410 polygons)
• marker_smooth.obj : Untriangulated Marker after three passes of Catmull-Clark subdivision (89046 polygons)
• marker_smooth.stl : Smoothed Marker for printing

Feel free to subdivide the base model yourself in your favorite 3D modeling program to as high a resolution as you desire.

How I Designed This

To make a marker that when saved as an STL file appears smooth, without an obvious single seam on each face, the geometry of the marker must be subdivided.

One approach would be to mark appropriate hard edges and use Catmull-Clark subdivision in an attempt to smooth out these quads.

However the original faces are already triangulated, and so attempting to smooth them results in a bit of a mess where when printed the original triangle seam will still be clearly visible:

Original mesh before subdivision - wireframe on left, smooth shading on right

Original mesh after subdivision - wireframe on left, smooth shading on right

Note how, despite having been smoothed, you can still clearly see where the original triangle seam was on each face.

This is one of the reasons why polygonal modelers strive for quad-based topology: triangles don't subdivide nearly as nicely as quads.

A better, but far more laborious approach to improving 3d printed markers then is to manually un-triangulating the entire mesh, reducing it from 4315 edges and 2873 polygons to 2785 edges and 1410 polygons:

Original mesh on left, un-triangulated mesh on right

So far nothing has really changed. If exported as an STL, the model will once again be triangulated, resulting in similar seams.

However being made almost entirely of quads, the topology can now be subdivided really nicely. Here is a comparison of 3 levels of subdivision with the old triangulated mesh, and with the new non-triangulated mesh:

Wireframe On - Subdivided original mesh on left, subdivided un-triangulated mesh on right

Wireframe Off - Subdivided original mesh on left, subdivided un-triangulated mesh on right

When the new subdivided mesh is exported to an STL it will also triangulate, but the change in slope is far more gradual over the surface, and so the triangles are much less noticeable.

Category: Video Games