I work as an Application Engineer for SpaceClaim, which means I spend a large portion of my waking hours using the software. Which, it turns out, allows me to create a model with far more detail that is probably FDA approved. I began work on a scale model of a dragonfly last August as a response to some of the new functionality we were introducing into SpaceClaim 2009. Here is what I ended up with:

Almost Finished Dragonfly

I learned a lot about SpaceClaim while building this little bug, so I figured I could share the experience and maybe show others what it can do. And possibly stroke my ego a bit while I’m at it.

The Idea

When I started, I was thinking more of a steampunk style insect. I had probably seen a picture on BoingBoing that I thought looked neato, and I remember searching Wikipedia for insect wings one afternoon. I found these:

Front View of Wings

Close-up of Wing Joint

After finding these images it didn’t take me long to drop the steampunk idea. I figured that the actual natural forms would be an interesting change of pace; I have already built a million boxy designs in SpaceClaim.

The Wing

From here I began with the wing. This was easily the most tedious part of the project. I traced somewhere between a lot and a ton of intricate little wing veins. I imported the image right into my design, and set the scale to be around 3 inches (it’s a BIG dragonfly). Using layout curves allowed me to switch back to 3D without forming surfaces. I organized the veins into four rough classes, by thickness, and gave each a layer (note the “layoutPlane” layer, used to hide the datum plane but not the curves). I could then set lineweights and colors to help visualize the wing structure early on.

Layers for Wing

I carefully traced every tiny vein in the wings using lines and arcs. It was around this time that Blake caught wind of what I was working on, and I think I nearly moved him to tears. While he may have been a little overdramatic, he did offer some good advice: too many picks in too short a time can lead to stress fractures (ask him about it). I took caution and paced myself, using the same process to create both the top and bottom wings, which would be mirrored in the final model. Here’s the general progression of the top wing:

At this point I had in the vicinity of 1000 curves drawn for each wing. It was unfeasible to create a cylinder or sweep for each curve by hand, but luckily Blake had just written an Add-in that did just that. His “Skeletize” tool allowed me to take the thousands of edges and create a solid skeleton from them (this functionality actually made its way into SpaceClaim proper, under the Cylinder tool). I broke the layout curves into smaller groups and projected them back into sketch curves, then went to 3D to create surfaces. SpaceClaim will only convert 200 sketch curves to surfaces in one go, but I wanted to have smaller surfaces to help with rendering later on anyway. After combining all the new solids I had two wings, each with one solid representing all of the veins and about eight surfaces forming the wing membrane.

Moving On – The Tail

With the easy but slow part done, it was time to dig into to the body, and I chose to start with the tail. Again, I went back to Wikipedia for a source image:

Side View of Tail

I blocked out the rough components very quickly using cylinders and spheres, just to get a sort of base to work with. I did some sketching where the primitives weren’t giving me enough, like the legs. This allowed me to structure my model, creating the sub-assemblies and layers I needed.

Moving into more detail, I began assembling the segments of the tail. I don’t really know the true physiology of dragonfly joints, so I took some liberties and simplified. I made simple slot-and-tabs with Center associations for each of the six segments.

Tail Joint Cross Section

I repeated this down the tail to the tip, which has some form of a pincer at the end. This I formed from some simple blends, then I applied similar assembly conditions as the existing segments.

To create some simple “veins” on the body, I chose to imprint the faces with intersecting datum planes, and then use the “Skeletize” tool again to create raised regions I could use the new Color Face commands on.

Slicing Up the Tail

Legs and Head and Body, Oh My!

I’ll come back to explain the process on creating the legs, head and body of the dragonfly, as well as assembling the whole thing later.