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COM6503: 3D Computer Graphics

Assignment 2 (60%): Making objects and scenes look less pristine in Computer Graphics

Deadline: 3pm, Tuesday 16 January, 2024

1. Introduction

Realism in computer graphics can be considered in many ways. Examples include photorealism (e.g. can we distinguish a rendered image from a real image?), behaviour realism in a simulation (e.g. does that simulated human movement look real? does that human skin behave realistically?), interaction realism (e.g. does that object behave correctly when dropped from a height? does that material deform when compressed?) and functional realism (e.g. is the functional behaviour clear irrespective of how the scene is rendered, for example, can I repair my appliance using those nonphotorealistically rendered instructions?)

This assignment is concerned with a specific aspect of photorealism: how to make rendered scenes look less pristine. Look around you at the surfaces and objects in your vicinity. You might see dusty and dirty surfaces, scratches and dents on objects and parts of the scene that look old through wear-and-tear. I’m sure you can think of other examples. But how are such appearances created in computer graphics renderings? The focus of this research study is on the use of texture-mapping approaches to achieve less pristine renderings.

Learning Outcomes

This assignment addresses the following module learning outcomes:

• Identify and compare a range of techniques for increasing the realism of rendered scenes;

• Summarise and appraise information on a specific topic in computer graphics.

2. The report

Structure

• The report should start with a short introduction to the general topic and your reasoning behind the report structure.

• This should be followed by some further sections that structure the parts of your report. It is your decision what sections you will use to structure the report and what the order of these sections should be.

• The report should finish with a short conclusions section.

• The report must be illustrated as described in the next section.

Illustrations

These are an important part of the report – they must be integral to the discussion, not an afterthought. You will lose marks if these illustrations are not included. Their connectedness to the discussion will be considered in the marking.

The following must be included:

• Screenshots from assignment 1: You must use at least three screenshots from Assignment 1 to illustrate your report. These should be examples where you have made changes to your program from Assignment 1 to make the rendered scene look less pristine. For example, using texture-mapping, you might add some dirty marks to the alien’s clothing or you might use diffuse and specular textures to make the security lamp look rusty, etc. If you wish, you can also add an extra object that has imperfections. You must decide what changes to make. There should be at least three unique changes. You should show before and after pictures from making a change and you should also show the texture maps that have been used and describe how they have been used.

• Photographs of the real world: You must take three photographs from the real world that show real-world objects or scenes that look less pristine. These must be used as illustrations in your report. You might also use some extra photographs that show close-up views of parts of your photographs, or, if the resolution is good enough, you can just zoom in on parts of your photographs. Try to take photographs that match some parts of your scene from Assignment 1, e.g. some dirty marks on clothing. This would then allow you to contrast the real photograph with your simulated version using texture maps.

• Illustrations using commercial software: You must make at least three illustrations using commercial software to illustrate techniques that can be used to produce less pristine renderings. This will involve you learning how to use free commercial software such as Unity or Blender to do this – both these pieces of software are free to students. These could be renderings of example objects that look less pristine. Your main text would then describe what techniques are used in producing the less pristine rendering effect. If the techniques improve on the examples used in ‘screenshots from assignment 1’ that gives you something else to discuss.

• You can also use some general illustrations from my lecture notes and from the Internet. However, you must check the copyright permissions before you use any illustrations from the Internet.

Things to consider

The following is a list of some of the things you might consider in your report:

• At some point in your report, you might consider the language and terminology you will use to refer to old, worn, dirty, aged objects and scenes. What kinds of imperfection might be considered? What does it mean to be not pristine? What might cause something to be not pristine? Misuse? Time? Interaction with other objects? Some other reason? Is it important to consider the cause of an effect? Put your personal, individual ideas into this – what do you see when you look around at indoor and outdoor spaces that you know?

• The focus of the research study is on texture-mapping approaches that can be used in rendering less pristine scenes. What can be achieved using texture-mapping approaches and what cannot?

• An aspect you might consider is how to control the use of techniques to produce non-pristine surfaces. For example, how might you control the application of imperfections? Is it a labour-intensive, manual process or can it be automated in some way? This consideration might include discussions of cause and effect (can a program automatically add an imperfection based on some interaction) and artistic control (if a program decides the imperfection, is artistic control lost?). Also, is time part of the consideration, i.e. change in an imperfection over time?

Decisions and skills

As part of the assignment, you will need to make decisions about what should be presented, make decisions about the ordering of information, decide what should be assumed and what should be explained (you can assume I know about my lecture notes – as an example, there is no need to explain the detailed workings of any common texturing approach covered in my lecture notes; a brief summary using a diagram would suffice), link to reliable information sources, and use appropriate language in your report. You are finding, understanding, filtering, organising and presenting information. You are demonstrating that you can summarise and appraise information about computer graphics.

References

I expect to see at least five published research papers in your reference list, as well as other kinds of reference, e.g. online materials that are reputable.

The following are a few published research papers you might consider, the titles of which you can use to search for more papers at Google Scholar (https://scholar.google.com):

• Becket W, Badler NI. Imperfection for realistic image synthesis. Journal of Visualization and Computer Animation 1990;1(1):26–32

• Bellini, R., Kleiman, Y. and Cohen-Or, D., 2016. Time-varying weathering in texture space. ACM Transactions on Graphics (TOG), 35(4), pp.1-11.

• Mérillou, S. and Ghazanfarpour, D., 2008. A survey of aging and weathering phenomena in computer graphics. Computers & Graphics, 32(2), pp.159-174.

3. Deliverables

• The report should be 3000 words (+/- 10%). This total does not include the list of references, the figure captions or any appropriate tables of information. You may include as many pictures as you deem appropriate.

• You should submit the report via Blackboard as a pdf document.

• You must include the following statement at the start of the report:

/* I declare that this work is my own.

Author: < name >, < email address > */

4. Marking

The following aspects will be considered equally:

• Coverage of the topic area and relevance of material – Is the material included relevant? Is there evidence of independent reading to find advanced/interesting information for the report? Are the references good?

• Knowledge and understanding of relevant material – Do you demonstrate knowledge and understanding of what you are writing about? Is deeper understanding demonstrated by comparing and contrasting ideas? Is your information accurate, or is some of the material misleading or even incorrect, demonstrating that you don’t understand it?

• Organisation, clarity of expression and illustrations – Is the report tidy and organised, with a good flow of information? Are all points in the writing expressed clearly and succinctly, and supported with the use of diagrams? Good use of illustrations. Are all the requested illustrations included? All illustrations should have a figure number and a caption and be referred to from the main text.

5. Other

• Use of generative AI tools (e.g. ChatGPT): If you make use of such tools, you must include an extra Appendix to your report that describes exactly how the tools have been used, including any prompts you used with such systems. This Appendix does not count towards the word count of the report. However, please bear in mind what it says in the Department’s student handbooks:

o UG: https://sites.google.com/sheffield.ac.uk/comu ghandbook/your-study/assessment/generative-ai-and-assessments

o PGT: https://sites.google.com/sheffield.ac.uk/com pgtstudenthandbook/home/your-study/assessment/generative-ai-and-assessment

• Standard lateness penalties will apply.

• Turnitin will be used to check for use of unfair means.

• See the Department’s student handbooks for more detailed information on lateness penalties and unfair means:

o UG: https://sites.google.com/sheffield.ac.uk/comu ghandbook/your-study/assessment/

o PGT: https://sites.google.com/sheffield.ac.uk/com pgtstudenthandbook/home/your-study/assessment/