Assessment is a delicate task in the overall teaching process because it may require significant time and may be prone to subjectivity. Subjectivity is especially true for disciplines in which perceptual factors play a key role in the evaluation. In previous decades, computer-based assessment techniques were developed to address the above-mentioned challenges and to automatically grade students' work in a variety of educational fields. In this paper, the application of automatic assessment strategies in the unexplored domain of computer graphics is discussed. In particular, a tool that is designed to evaluate student assignments for a 3D computer animation course taught at Politecnico di Torino University is presented. During laboratory examination sessions, students are requested to individually operate on the open-source Blender suite and to recreate a 3D animation similar to a reference one. Student's output is assessed against a set of similarity indicators, which are specifically designed to capture the technical and perceptual factors that would be blended in a traditional teacher's evaluation. A comparison of the results that are achieved by the computer-based tool with grades assigned by visual inspection confirms the effectiveness of the designed approach and displays a high-quality concurrence between automatic and manual evaluations.