Tutorial, modeling a tyre.
This is my method for modelling car tyres. It takes a bit of preparation but I believe the accurate results that can be achieved are worth the effort.
First, you need to find some reference. You can go out and photograph a tyre yourself but you can often find some nice sharp, studio lit photographs online. For instance, after a quick search, I found some great reference for the Bridgestone Potenza tyre on the manufacturer’s website. With a bit more searching, I found a higher resolution image of the sidewall too.
You need to figure out how to split the tyre up into manageable sections. Looking at the side view, you can see that you can split the tyre up into sections where a groove in the edge meets the sidewall. In this tyre, there are 30 sections.
Looking closely at the photo of the tread, it would appear that each section is not the same length. I believe this has something to do with road noise. It’s fine, we’re not going to worry about it. The image of the sidewall shows all the segments to be the same length, if it’s good enough for the manufacturer’s website, it’s good enough for me!
Try and find a segment that you can use and cut it out in Photoshop. Ideally you want the segment to be as face on towards the camera as possible.
2. The Tread
Create image planes for the front and side cameras using the reference images from earlier.
To create the image planes, click ‘View’ in the menu of the camera view that you want to use. Then go to ‘Image Plane’ > ‘Import Image…’ and choose the appropriate reference image. You can use the ‘Placement Extras’ in the attribute editor to position and scale the image. Take care to ensure that they line up in relation each other as closely as possible. Also, make sure the front image is centred upon the origin.
To get the image planes a bit more out of the way, move them away from the central axis in the ‘Placement Extras’. You can also reduce the alpha gain and choose ‘looking through camera’ in the ‘Image Plane Attributes’.
Now you need to create a nurbs guide shape. This will make it easier to model the tread segment properly later.
Draw a curve to match the profile of the tyre.
Choose the ‘Surface’ menus and go to ‘Surfaces’ > ‘Revolve’ > options box. Make sure that the Z axis is selected and that you’re using NURBS.
In the front view, create a cylinder on the origin. You want the ‘Subdivision Axis’ to be a multiple of the number of tyre segments. In this case, I chose 120 (4 x 30). You may notice that the front and side views don’t align exactly. This is an inevitable consequence of the fact that any image captured with a camera will have some distortion due to perspective. The part of the tyre closer to camera will appear bigger than it should be if the photo was a perfect orthographic view.
Select enough polygons along the top to make one segment. Go to ‘Edit’ > ‘Invert Selection’ and delete the rest of the polygons.
Make the NURBS object live. Making an object live will make sure that vertices etc. snap to the surface of the object.
Same as before, create an image plane in the top view. Line it up to the polygon segment you created earlier. You may find that you need to rotate and scale the image in Photoshop to make it best fit your tyre.