Periodic Reporting for period 2 - ApPEARS (Appearance Printing - European Advanced Research School)
Reporting period: 2021-04-01 to 2023-11-30
Humans are highly skilled in assessing the appearance of objects. By comparing the relative qualities of materials, such as whether they are flexible or rigid, soft or hard, smooth or rough, rotten or fresh, we can quickly tell if these are pleasing or may do us harm. Understanding the appearance of materials is also of great importance for commercial products. Better understanding leads to better choice of material, which can be a key differentiator between the success or failure of a product.
2.5D or and 3D printing make it possible to reconstruct the texture and appearance of a wide range of surfaces. However, a fundamentally neglected part of the workflow is the ability to match the desired appearance of materials (in terms of colour, texture, glossiness, softness, translucency) in real life.
The overall academic objective of the ApPEARS project has been to train a new generation of Early Stage Researchers (ESR) towards a common goal – to ensure the accurate reproduction of the desired visual appearance attributes of materials/ objects using 2.5D and 3D printing techniques.
The ApPEARS ESRs have extended our understanding of the appearance of prints from two to three dimensions by:
- Identifying the attributes that are correlated to the visual appearance of 2.5 and 3D surfaces
- Quantifying their impact on appearance and appearance matching
- Finding suitable measurement techniques to assess these attributes
- Explaining and modelling the relationship between physical material properties and psychophysical appearance attributes
- Defining a reference appearance space with the most relevant properties to communicate appearance most efficiently
2.5D or and 3D printing make it possible to reconstruct the texture and appearance of a wide range of surfaces. However, a fundamentally neglected part of the workflow is the ability to match the desired appearance of materials (in terms of colour, texture, glossiness, softness, translucency) in real life.
The overall academic objective of the ApPEARS project has been to train a new generation of Early Stage Researchers (ESR) towards a common goal – to ensure the accurate reproduction of the desired visual appearance attributes of materials/ objects using 2.5D and 3D printing techniques.
The ApPEARS ESRs have extended our understanding of the appearance of prints from two to three dimensions by:
- Identifying the attributes that are correlated to the visual appearance of 2.5 and 3D surfaces
- Quantifying their impact on appearance and appearance matching
- Finding suitable measurement techniques to assess these attributes
- Explaining and modelling the relationship between physical material properties and psychophysical appearance attributes
- Defining a reference appearance space with the most relevant properties to communicate appearance most efficiently
Within the ApPEARS project period, the Early-Stage Researchers (ESRs) of the project have worked on their individual projects that include topics like measuring appearance, finding models to control, predict and accurately reproduce the appearance of an original, as well as the simulation of the final appearance of a printed product. Identifying commercial applications, and strengths and weaknesses of current printing workflows are also important aspects the ESRs have looked into to help us understand the appearance of 2.5D and 3D prints in a better way.
At the time of closing the ApPEARS project, most ESRs have completed their project where they worked on the above mentioned research topics, and some ESRs are developing devices useful for the industry. ESR1 at the Norwegian University of Science and Technology (NTNU) is designing and building a fast, cheap, and easy to use device that can be used to measure the amount of light reflected from material surface in different directions, making it easier for industries using 2.5D and 3D printing technologies to reproduce accurate material appearance.
More than 60 research papers are currently published and several more are awaiting approval from the journals or conferences. ESR 5 at the University of Linköping (LIU) have recently published several papers on the topic of ‘halftoning’. Research on halftoning for 3D prints is important, since many reproduction devices, e.g. printers, have a limited number of inks, which makes it difficult to reproduce shades of different colours. As a printer deposit ink drops on a piece of paper, ESR 5 is looking into the process of turning an image into ink spots, called halftoning. Halftoning has a constructive impact on the visual quality in printing, and ESR 5 is investigating aspects of adapting and applying 2D halftoning algorithms to halftone 3D surfaces.
Another example is ESR 7 at the University of Leeds who has completed her research that will improve the appearance of 3D printed facial prostheses. Facial prostheses have become highly desirable to print, due to the advantages in customization, direct interconnecting with manufacturing, and saving materials as well as cost and time. It is, however, challenging to keep the colour appearance of the 3D printed prostheses consistent under different illuminations. ESR 7 has been working on a digital imaging system capable of measuring human faces specifically for skin measurement, understanding and modelling light interaction in human skin for appearance rendering and simulation, to improve the 3D printed facial prothesis.
Other ESRs as well have published their results, and all current publications are available on the ApPEARS website: https://www.appears-itn.eu/dissemination/publications/(opens in new window). The list will be continued updated also after the project is closed.
During the ApPEARS project, the ESRs have received comprehensive training in subject fields like imaging and material science, appearance capture and reproduction workflow, as well as appearance metrology. In addition, they have received training in transferrable skills (like research ethics and project management) that is important for their research career. In total, six training events have been conducted, one in France 7 months into the project, two in Norway in month 10 and month 42, a combined France/Germany event in month 32, one in UK in month 36 in addition to a virtual event in month 18. A career development plan and a data management plan are developed by each ESR to achieve their career goals and for dissemination and exploitation of their research results.
The Covid-19 pandemic has played a major role in delaying some of the planned project activities. ESR secondments to the project beneficiaries and partners were delayed, reduced in duration and some even cancelled.
At the time of closing the ApPEARS project, most ESRs have completed their project where they worked on the above mentioned research topics, and some ESRs are developing devices useful for the industry. ESR1 at the Norwegian University of Science and Technology (NTNU) is designing and building a fast, cheap, and easy to use device that can be used to measure the amount of light reflected from material surface in different directions, making it easier for industries using 2.5D and 3D printing technologies to reproduce accurate material appearance.
More than 60 research papers are currently published and several more are awaiting approval from the journals or conferences. ESR 5 at the University of Linköping (LIU) have recently published several papers on the topic of ‘halftoning’. Research on halftoning for 3D prints is important, since many reproduction devices, e.g. printers, have a limited number of inks, which makes it difficult to reproduce shades of different colours. As a printer deposit ink drops on a piece of paper, ESR 5 is looking into the process of turning an image into ink spots, called halftoning. Halftoning has a constructive impact on the visual quality in printing, and ESR 5 is investigating aspects of adapting and applying 2D halftoning algorithms to halftone 3D surfaces.
Another example is ESR 7 at the University of Leeds who has completed her research that will improve the appearance of 3D printed facial prostheses. Facial prostheses have become highly desirable to print, due to the advantages in customization, direct interconnecting with manufacturing, and saving materials as well as cost and time. It is, however, challenging to keep the colour appearance of the 3D printed prostheses consistent under different illuminations. ESR 7 has been working on a digital imaging system capable of measuring human faces specifically for skin measurement, understanding and modelling light interaction in human skin for appearance rendering and simulation, to improve the 3D printed facial prothesis.
Other ESRs as well have published their results, and all current publications are available on the ApPEARS website: https://www.appears-itn.eu/dissemination/publications/(opens in new window). The list will be continued updated also after the project is closed.
During the ApPEARS project, the ESRs have received comprehensive training in subject fields like imaging and material science, appearance capture and reproduction workflow, as well as appearance metrology. In addition, they have received training in transferrable skills (like research ethics and project management) that is important for their research career. In total, six training events have been conducted, one in France 7 months into the project, two in Norway in month 10 and month 42, a combined France/Germany event in month 32, one in UK in month 36 in addition to a virtual event in month 18. A career development plan and a data management plan are developed by each ESR to achieve their career goals and for dissemination and exploitation of their research results.
The Covid-19 pandemic has played a major role in delaying some of the planned project activities. ESR secondments to the project beneficiaries and partners were delayed, reduced in duration and some even cancelled.
The refinement of appearance printing beyond colour in 2.5D and 3D printing was expected to generate very attractive tools for many different fields and applications, including but not limited to skin prostheses, packaging, design, and art reproduction applications. By bringing in support and supervision from experts in different fields like visual computing, 2.5D and 3D printing, colour, digital imaging, computer graphics, healthcare, engineering, psychology, applied mathematics, etc, the Early Stage Researchers (ESRs) have been trained towards becoming top-level researchers in a field where there has been a critical shortage of PhDs. When wrapping up the project, we are very happy to receive feedback from our industry partners saying the ESRs' work have improved their methods and contributed towards standardisation within appearance printing. The results have answered questions as well as uncovered new ones and several ESRs have developed algorithms, methods as well as devices for the industry.
At the end of ApPEARS, we are one step closer in standardisation of the printing and manufacturing sector undertaking appearance printing using 2.5D and 3D printing technology. ApPEARS’ multi-disciplinary approach has led to a deeper understanding of different methodologies in the areas of material appearance understanding, measurement, printing, and application areas. ESRs are continuing their careers with new employees, bringing in their expertise gained in ApPEARS while others are building on their work with consortium members. Either way, the work of ApPEARS will continue as new projects and new research questions building on the groundwork conducted by the consortium members of ApPEARS.
At the end of ApPEARS, we are one step closer in standardisation of the printing and manufacturing sector undertaking appearance printing using 2.5D and 3D printing technology. ApPEARS’ multi-disciplinary approach has led to a deeper understanding of different methodologies in the areas of material appearance understanding, measurement, printing, and application areas. ESRs are continuing their careers with new employees, bringing in their expertise gained in ApPEARS while others are building on their work with consortium members. Either way, the work of ApPEARS will continue as new projects and new research questions building on the groundwork conducted by the consortium members of ApPEARS.