We created a set of wheels from a cylinder which we then scaled, duplicated and used inset and extrude to provide a little detail on each wheel.
We then created a bezier curve to define the shape of the track across then wheels. Bezier curves are an easy way to defined a smooth shape. They have a number of points through which the curve passes. Each point has a pair of handles. The rotation of these handles defines the angle at which the curve passes through the point. The distance between the handles defines how tightly the curve bends as it approaches the point.
Once we finished the apple, we started to talk about animation. To illustrate this, we started building a little multi-object tank model that we can later animate. Here are the instructions on starting the tank model:
This week we had a 3D printer in the room, so our plans to stencil paint the apple took a back seat until next week. Instead we printed a dice model and then looked at how to build that model.
The printer we used is a Prusa i3 Mk 2.5. To print a model you import it into a program called a slicer which converts it from a polygon based model into instructions for the printer in how to lay down a series of layers of plastic to build the same approximate shape.
The model we printed was a dice. To do this we used ‘hard surface modelling’ techniques, specifically the use of boolean operators. Boolean operators allow you to take two shapes and make a composite shape that is:
Difference: The first shape with the second cut-out
Union: A shape which is the two shape fused together
Intersect: A shape which is only where the two original shapes overlapped
This technique is powerful, but it results in many N-gons (polygons with more than four sides). N-gons are bad in many circumstances. For example severe distortion may result if :
If we try to apply smooth shading
If we try to apply a subsurface modifier
We later try to distort the mesh, as with an animation
If we export the model for use in other 3D packages
If none of those apply, hard surface modelling can have its uses.
This week we looked at colour and generating textures.
White light contains all other colours; we can see this when a prism splits it into a rainbow. A green object appears green because it absorbs other colors and bounces the green light back and into our eyes.
When we render an object in Blender, or any other 3D software, we want the renderer to generate the highlights (specular reflections) and shadow on the object. Any texture we use should be as free of highlights and shadow as possible.
To generate a relatively highlight and shadow-free texture of an apple, we used a pop-up portable photo studio. The interior of this box is white and reflective and lights the object relatively evenly on all sides.
We photographed the object, an apple in this case, at four angles around the circumference and once again for the top and bottom of the apple respectively. This left us with six shots of the apple from all sides.
I then opened each shot in Gimp (the image editing software), and removed as much of the rest of the image, everything that wasn’t apple, as possible. To do this I:
Used the Rectangle Selection Tool to select a box close in around the apple and then used Image | Crop to Selection to remove the rest of the image
Used the Fuzzy Selection Tool (aka. Magic Wand tool) to select white areas. I adjusted the Threshold value in the Tool Options panel as high as possible so that no parts of the apple were being selected when I clicked. I then used Edit | Cut to remove those portions.
Finally, there were portions of the supporting bowl that were still remaining. I used the Free Select Tool (aka. Lasso Tool) to select these and remove them.
Once I had each photo of the apple cleaned up, I created a new image, and pasted all the individual images into it, scaling them so that they were close to the same size. The result is here:
We also built a simple apple model by shaping a UV sphere. Next week we are going to stencil paint the apple model with this texture.
Hi Folks. Minimal notes this week as we spent the session working with the sculpting tools in Blender; something you really just need to try for yourself.
To start a new sculpting session, just choose File > New > Sculpting to be presented with a high-resolution quad sphere and an array of sculpting tools.
Of these tools there are three I find most useful:
Draw: Normally pulls out the mesh, but will create depressions when CTRL is held
Crease: Makes fine creases in the mesh. Great for adding detail
Smooth: Great for when the mesh has become a little rough or uneven
You should experiment with the others to see which you like best!
Finally, here’s a little rough and unflattering 10min self-portrait I knocked up at the end of the session, just for laughs:
When sculpting, it a good idea to remesh from time-to-time where you’ve significantly deformed the mesh. Remeshing evens the mesh spacing automatically, avoiding places where individual polygons are overstretched, but it’s only available in Blender 2.81. Some people had this version already installed, while others installed it during the session. If you haven’t got it yet and would like to install it you can get it here.
Finally, here’s little personal project you might like to see. I sculpted and painted my cat Noodle’s head. I used a couple of reference photos and a technique called stencil painting to generate the texture:
Hi folks, hard to believe this was our last regular session of 2019. Next week is our Christmas pizza party and show-and-tell.
This week we took a photo of a cereal box and UV mapped it to a simple cube which we scaled to the appropriate proportions. One we made our model we built a very basic studio setup and did our first render with a camera and a light.
This week, we took the mug we’d created the week before and UV unwrapped it again. We’d covered that last week too, and it’s in last week’s notes, but because we’d rushed a little we went over it again.
One the model was unwrapped, we created an image texture and manually painted it. We then used the GIMP image editing program to add an image to our texture.
This week we started looking at texturing. Texturing is the process of taking an image, which is flat, and mapping it onto a 3D object, which generally isn’t.
UV maps are just the plan that shows which part of the texture goes to which part of the 3D model.
Unwrapping is the process of taking the 3D surface of the model and laying it flat, like peeling an orange. This flattened version of the model, when placed over the texture becomes the UV map.
The animation above illustrates the process for a simple shape as if we really were unfolding the shape manually. In reality, we just tell Blender where the seams are (where it can cut the model’s surface) and the rest can happen automatically.
This week we continued our sword model. We finished the blade and started work on the guard.
We didn’t introduce any new concepts this week, but we did make our first practical use of the mirror modifier to allow us to create one side of the sword guard and have the other side created automatically.
Here are the video instructions from this week:
The matching model file can be downloaded from here.