Cross Section Modelling - Part 1

Objects whose cross section does not vary greatly over their length can often be modelled quite easily using a modelling technique called Cross Section Modelling.

bulletIn order to use this technique you will need a side view and a front view of the object you plan to model. You may be lucky and find a set of plans for the object you want to model, or you can create one yourself from photos.

This particular side view and front view were traced from a set of plans for a BLS 465 locomotive created by Tobias Benjamin Köhler. (http://mercurio.iet.unipi.it/).

The nice thing about this particular locomotive is that it does not change largely from its cross section for most of the model. Also, it is symmetrical front to rear which means we only have to model half of it.

 

 
bulletOnce you have your plan, create a square image from the front view of the plan. This square image can be created using a paint program.

The resulting cross section will be scaled in a later step.

 
bulletDrag and drop an "Extrude Tool" object on to your scene.

Change the background grid to your cross section by clicking .
 

 
bulletTrace your cross section. Points will be added as you click along the boundaries of the cross section. The default behaviour for the Extrude Tool is to create curves between points. To create straight lines between points click each white point a second time to make them a fixed (blue) point.

 
bulletThe bottom part of this model is curved. You can choose to let 3D Canvas create the curve by using non-fixed control points or you can simulate the curve yourself using a series of fixed points.

 
bulletThe cross section is complete.

 

 
bulletNow add a bit of depth so we get a cross section. Click on the bottom left panel, and then again just to the right of your initial click. Be sure that the the two points are at the same vertical level so that you get an entirely vertical cross section.

Close the Extrude Object Building Tool, and click "Yes" to updating your document.

Part 2 of this tutorial will cover the process of using background images to draw the remainder of the model.