Extra lines dividing a face - 3d investigation


#1

Continuing the discussion from Automatically repeat the same action to multiple selected objects?:

The discussion between myself and @Box in the aforementioned thread caused me to investigate further.

It turns out the “extra” lines DO serve a purpose when exporting to .stl format! It helps in the triangulation! Remember that .stl files are always triangulated. So, my original looks like:

Note: assembly produced from a single, non-solid component, array copied to original and 35 copies, then edges added - finally grouped everything into a single component. SU said “solid” and Solid Inspector 2 said “no problem”. I exploded the 36 individual components, then deleted one line to make the one rectangular appearing piece.
Then I exported to .stl, opened a new SU window, and imported the .stl:


As you can see, it imported in a form made up completely as triangles. In fact, to make the needed triangles, it added back the line I removed!

I learned something new today - thanks to @box prodding me!


Importing collada dae files into SU 8
#2

Interesting.
When I export mine to .stl then import that .stl I get this.


#3

SktechUp hides the planar triangles as faces and boundaries. If you import the STL file into MeshLab (or similar), you will see the underlying triangles that SketchUp hides:

[added]

It’s the same if you export the file as a Collada file: