# Quiz

Model fitting is always the first step in analysing a shape and is thus crucial for any application of shape modelling. Here are some questions that let you check your understanding.

### Question 1

In order to analyse a shape using the model, we need to find a deformation field. What are the requirements for this deformation field? Multiple answers are possible.

### Question 2

Can we expect the Iterative Closest Point (ICP) algorithm to find a global optimum?

### Question 3

The ICP procedure can be stopped at two instances: after the search for closest points, (which will lead to a discrete deformation field that matches the target contour exactly) or after applying Gaussian Process regression, where we do not necessarily match the contour. Are there cases where it is better to stop the procedure after the regression step?

### Question 4

Assume have a model where the deformations at every point are independent (think of a model whose covariance function is a Gaussian kernel with smoothness parameter close to 0). What can we say about the result of the ICP procedure?

### Question 5

What is the advantage of using the shape model as prior knowledge for finding the deformation field that relates the reference to the target shape? Multiple answers are possible.