Building a double hulled catamaran out of ice-cream sticks isn’t the same as building a ship. Naturally, it didn’t involve using a computer nor did it need any numbers.
So, the next try was with a software called blender. Using blender, I first created a rudimentary “kayak / canoe” — well I call it a Kayak, but it is just a weirdly shaped bathtub object. (See object file image below). But, it floats. This article in the series is about building this using Blender.
Just to be fair — we are building this because it is conceptually simpler than the better version (Canoe) I built (screenshot of object file below). The only reason we won’t be working on this model and instead work on the uglier one above — is the complexity of Blender. Blender has a pretty steep learning curve, and it is rather intimidating for beginners. If you are comfortable with blender however, feel free to play around and make this one below.
Blender(r) is a free OpenSource graphics / modeling software that is capable of doing far more than my meagre abilities. However, it is a good software for non parametric design. By this, I mean — you can design stuff freehand and not be worried much about precision. This comes in handy if one uses the end product for 3D printing. In fact, blender is so powerful and feature rich that it is used to produce full length movies. Leaving that aside, we will see how to create a canoe with blender.
Open blender (duh!) and you will see a screen like the one below. Click on “General” — highlighted below. If you are new to blender, you will see a cube and a camera in your opening canvas in “general”. Don’t worry — select and delete them. Clean slate.
**Save this file** — give it a convenient name.
In the canvas / blender interface, press “Shift + A”. You should see a menu like this >>
Click on “Mesh” — top of the menu, and then choose circle (don’t click your mouse after that yet). Once you choose circle, you will see another sneaky menu on the bottom left of your screen. Like this
Click on the Arrow and expand the menu to get this:
You see a few things.
- The circle isn’t a pure curve here. It is actually a polygon made of n-vertices (n edges as well). The higher the number of vertices, the better the approximation to a pure curve circle is. However, it also makes your program very very greedy with RAM. Know that this software can take all the RAM you can provide it, and not complain at all. While high resolution / high vertex count looks shiny on the screen, know that it will crash your system. This is true of anything you do on blender. My circle has 32 vertices.
- The radius is actually pretty large (1 meter). There are two ways to deal with it. One, create the model in meters, and then size it down a few %s (10% for 10cm) when printing. The second, change the radius here and now. Know that you will have to size everything you add to your preferred scale. Choose your pain. I chose a radius of 5 cm. If your units are in metres (m) instead of cm, use an appropriate fraction (0.05m is 5 cm).
- The location and rotation are self explanatory, though we won’t need them changed for this project. So, I would let them be.
Now hit “Enter” to make the changes. Click on the screen (away from the menu) to make it go away. You have your circle.
See the top left of the screen and you will see another sneaky menu that says “Object Mode”, with a white square.
Press the drop down arrow and choose “Edit Mode”. Alternatively, hit “Tab” to toggle between “Edit Mode” and “Object Mode”.
[Oh! btw, remember the “Shift + A” circus to get a circle? You could do the same by clicking “Add” in the menu shown above*. I find keystrokes to be far faster than moving the mouse. Just know that almost every keystroke combo I use for this, has a menu option that you can click and get away with.]
Once in “Edit Mode”, the menu above will slightly change >> (underscored part).
The first box is for viewing / editing “vertices”. The second one is for “edges”, and the third — for “faces”. You see in my window, the “vertex” option is selected. It is possible that in yours, the “edge” is likely to be the default. I prefer working with vertices; so follow along and click that box. You can always try later with edges to see if that suits you better.
Blender expects you to know what you are doing, so the cues are subtle. To get familiar, click anywhere on the screen now (except on the circle circumference) — and you will see that the circle will go dark. This means nothing is selected. Now, press “A” (just the key for “a”, no need for caps). on the keyboard, and you should see the circle light up in orange. You should also see the vertices light up as orange dots and the edges as orange lines. The distinction should be very clear.
Next, unselect everything (click on empty space) and click on just one vertex. You should see the vertex + the lines leading from the vertex get highlighted (see image below). Note how the highlighting fades out before the unselected vertices on either side. (As an exercise, try selecting two or more adjoining vertices and see what happens). Understanding how selection of a vertex / vertices affect the edges connected to it / them, saves a lot of headache / heartache when it comes to blender.
Anyway — moving on to our kayakanoe — we have to shape it. To keep things simple, I merely created an elliptic. Here is how to do it.
- press “A” and select all vertices.
- press “S” — and it enters “scale” mode. Once in scale mode, we can do a uniform scaling (increase or decrease the overall size) by a given factor. Try pressing number 2 after pressing “S”. Hit enter → your circle should have doubled in radius (4 times the area now). Again, press “S” and type “0.5” (no quotes) and hit enter. Your circle is back to its original size.
- Do you notice the red line and the green line on your screen? They are the X and Y axes respectively. You can scale along specific axes (non uniform scaling). Now, let us try that and get this circle into a more useful shape.
- Press “S”. Press “Y” and type “2”. Hit “Enter”. What you just did is to scale up the circle by a factor of 2, along the Y axis.
- Press “S”, Press “X”, type “0.3”. Hit “Enter”. Figure out what you have done to the elliptic (homework).
- Your object — it is still named a circle in the menu on the right hand side — should look like this at this point. Mind you, the object looks uneven about the axes only due to the perspective in which you are viewing it. See the flower like object (circled in white) near the top right, click on it / move it around to change the perspective. To see it from the top (from where it will look symmetric), click on the Z on the blue ball. Also note how the X and the Y balls have the same color as your axis lines. Hint, hint!
7. So far, so good. However, we can’t do much with a line. We need to extend it across 2D (plane) and then 3D (shape). Let us get to it. First make sure all vertices are selected (press “A”). Next part is tricky — so follow the keystrokes carefully.
7a. Press “E”. Press “Esc”. Press “S”. type “0.8" — and voila, magic happens. (pressing Esc after E is crucial. For the brave of heart: Ctrl+Z works, so try this without pressing Esc and see what happens).
Now you should see something like this
So, what did we do? “E” is for Extrude. It would create a connected copy of the vertices / edges and then pull them (extrude) along a plane normal — to a specified distance. When we simply press “Esc” after “E”, we create a copy of the vertices / edges and leave them there. Conveniently, the new copy of the vertices is now selected (though you can’t see it apart). Then, when we type “S”, it goes into scale mode for the duplicate set of vertices. And upon scaling, it creates a face in the X-Y plane for the vertices. Since our X dimensions are smaller (1/6) than the Y-dimension, the scaling produces uneven thickness for the face. That is expected.
Why do we use “E” and “Esc” instead of duplicating the vertices? It is because duplicating the vertices creates an independent copy with no connection to the original. Whereas, E + Esc creates a copy of the vertices that are connected by an edge. That is what creates a Face in the plane of interest. If we were to do another select all (“A”) and extrude (“E”) now, with some distance (say, -1 cm or -0.01 m), then you will see a 3d shape in your screen. Let us do that. (note the negative sign; it means your extrusion will go below the surface — which is what we want. If it goes up; happens; just change the sign). Whenever you extrude, be mindful of the direction (and the sign of the number).
If you notice, the bottom of the 3d shape is selected. In fact, if you look carefully, you will see that both inner and outer rings are still selected. A better view for that is the transparent / mesh view. See the highlighted (blue) area on top right of the screenshot, you will see a wireframe version of a globe there (just lat-long). Click that to see your object in plain wireframe. Click and see what happens. You can always click the solid white circle to go back to opaque object view (homework: play around with the other views).
With all the playing around, it is likely the bottom layer vertices are unselected — don’t worry / don’t panic. Select transparent view (previous paragraph). Go the Axis selector (3 colored flower like axis object at top right of the screen) and click on either X or Y. Now, simply select the whole layer by drawing a box around it (hold your mouse and drag it to select all intended vertices.
Once you have selected the bottom layer, let us scale it down a bit — do the following: “S” → “0.8” → “Enter”. If you want a more gradual scaling, you can use a larger number (say, 0.85 or 0.9; less than 1.0, else it will expand).
Now repeat the extrude for another cm. Remember: you don’t have to do “E” → “Esc” for this. Just do “E” → “Z” → “-1” → Enter (or -0.01 depending on your units).
Repeat the scaling one more time (“S” → “0.7”); extrude a third time for 0.5 cm. (“E” → “Z” → “-0.5”). (Don’t forget the Enter)
Now we should have a semblance of a canoe shaped object. Switch the view to Z-axis (top view). You should see the innermost ring of vertices clearly. Keep your “Ctrl” key pressed and use your mouse to select the vertices in that ring. Note: you don’t have to click every point when you are holding “Ctrl” key. You have to click the vertices that are close enough so that the closest path between them is the ring. Rule of the thumb, once every three or four points will work fine. You should see that at the end of it, the ring of vertices is highlighted → like this.
We are going to seal this inner ring — there are two ways to do it. One, create a Face: simply press “F”. Or simply scale along X axis to zero. I prefer this for this object. So, “S” → “X” → “0” → Enter.
Now, switch to opaque view (top right corner, from wireframe globe to solid white dot). Click on the Z axis (flower like object on top right) again. You should see the bottom of the canoe now with a line running in the middle (that is the inner sealed ring). Select the innermost ring (not the straight line) as shown below. Use the same trick as above: hold “Ctrl” and click on the vertices to select them all.
Once that is done, extrude: “E” → “Z” → “-0.5”.
Then we need to do two things. 1. seal the face so that we have the keel, and 2. shrink the “Y” axis (long axis) a bit. Follow the keystrokes: “S” → “X” → “0” → Enter. [DON’T CLICK]. And finally, “S” → “Y” → “0.7” → Enter.
Hit “Tab” — and see the canoe in object view. You should see this:
We are almost there .. almost there .. just one last touch up.
See how you can see the segments in the canoe — the distinct flat faces? If you print this model, you will see this ugliness. It is what we call “low poly” or low polygon object. We will now convert this to a high polygon object.
**warning** :: if you overdo this, you will crash your computer. Save all your open documents. Close them. Save this file once.
Click on the object to select it. Now press “Ctrl”+1. That really ugly object will look smoother (like this)
My system has a lot of RAM (32G) and hence I can trivially go till 3rd level of smoothening for this object (“Ctrl + 3”). Listen to your system when you do this. This is called subsurface — subdivision modifier. What it does is basically divide your faces (polygons) into smaller and smaller pieces to create a smoother surface.
If you stuck around till this, congratulations. You completed your first canoe design in Blender.
PS: I know things on a screen don’t mean much in the real world — so, here is a photo of the printed object (kayak). Yes. This looks different from what we built up there, but you can always play around with the extrudes and scales. This is one problem of a non parametric model.
I did mention I designed a much better looking canoe — I designed it after the canoe used by Northern American Tribes. Here is a photo of the final product.
So long — and thanks for all the fish.
