Analysis of the Relationship Between Mural Content and Its Illumination: Two Alternative Directions for Design Guidelines

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1. The paper mentions the analysis of 7 murals, but the main text only shows 1 artistic mural + 3 commercial mural cases in detail. It is recommended that the summary data of the remaining cases (e.g., location, type, key conclusions) be supplemented or included in appendices to enhance statistical persuasiveness.
2. The conclusion calls for "municipalities to develop a mural lighting policy", but does not take into account the cost of implementation (e.g., the difficulty of making adjustable lamps widespread). It is recommended to put forward short-term (design tools first) and long-term (policy and regulation) strategies in layers.
3. The cases focus on specific areas of Warsaw (similar building heights, street widths). It is necessary to discuss whether the conclusion is suitable for scenarios such as narrow roadways and high-rise building facades.

Author Response

Dear Reviewer,

Thank you for your time and valuable comments. We hope our responses will clear up your doubts and that you will be satisfied. We have modified the article according to your suggestions.

1. The paper mentions the analysisof 7 murals, but the main text only shows1 artistic mural + 3 commercial mural casesin detail. It is recommended that the summary data of the remaining cases (e.g., location, type, key conclusions) be supplemented or included inappendices to enhance statistic alpersuasiveness.

This article analyses the illumination of seven murals in two Warsaw locations. Six murals were located on three adjacent walls. These are commercial murals. The murals on these walls change several times a year. For these, an analysis of the effect under constant lighting is presented, using both luminance measurements and computer simulations in the case of the first set (Figure 4). In addition, we presented an artistic mural too. This mural is a permanent one, but not lit. We have analysed the possibility of it sillumination.

2. The conclusion calls for "municipalitietodevelopa mural lighting policy", but does not take into account the cost of implementation (e.g.,thedifficultyofmakingadjustable lamps widespread). Itisrecommendedtoputforwardshort-term(designtoolsfirst)andlong-term (policy and regulation) strategies in layers.

Luminaires with adjustable luminous flux are small and not expensive. This depends on the control method. Remote-controlled fixtures are available on the lighting market, too. This does not require additional control systems like DALI, DMX, etc. Therefore, the cost of these luminaires is more or less double the installation cost of fixtures without controls. Assuming that the cost of such fixtures ranges from several dozen to several hundred EUR (depending on the company), in an installation of 10 luminaires, upgrading the lighting solely to improve the luminance level is not costly.

In our opinion, the more important issue is the Floodlighting Content Readability Map development. This requires the use of a matrix luminance meter, which is not inexpensive (costing approximately €20,000-100,000, depending on the resolution and manufacturer). It's important to note that a map-based system is used only once for a given mural lighting project. A map is created, which provides the graphic designer with a basis for developing the composition. Luminance level adjustments can be made using “point” measurements. The cost of such meters also depends on the company, but is 10-20 times lower. Matrix luminance meters are also available in mobile apps. Unfortunately, the results they provide differ from actual results. Therefore, validated devices should be used for the time being.

Is this a drawback? In our opinion, no. Many companies and research institutions currently use such devices, and with their help/consultation, the proposed system can be implemented. Luminance measurements are now commonplace and often mandatory. Every newly illuminated roadway is checked for compliance with standards.

In our opinion, this should also be done for murals usually located in road areas.

3. The cases focus on specific areas of Warsaw (similar building heights, street widths). It is necessary to discuss whether the conclusionis suitable for scenarios such as narrow roadways and high-risebuilding facades.

Our analysis is suitable for any mural location, height, or road width, as the luminance distribution is independent of these parameters. Even in areas with only pedestrian traffic, the readability of the illuminated mural should be maintained, and the illumination values should be adjusted to recommendations and standards. This situation can be applied to the illumination of the building.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The text is pertinent, it deals with a subject that is still little studied when it comes to urban art. Light, or rather illumination, is also symbolic, and its use can alter our reading of our surroundings. There is some work in the field of light engineering and architecture that is beginning to become known. It seems to me to be a good contribution to the subject.

Author Response

The text is pertinent, it deals with a subject that is still little studied when it comes to urban art. Light, or rather illumination, is also symbolic, and its use can alter our reading of our surroundings. There is some work in the field of light engineering and architecture that is beginning to become known. It seems to me to be a good contribution to the subject.

Dear Reviewer,

Thank you for your time and kind review. We have expanded our literature review.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The overall research framework of the paper is relatively clear. It proposes a practically applicable analytical frame focusing on the relationship between mural content and illumination, with a strong integration of images and data. However, the paper still has the following issues, and revisions are recommended:

1.The sample size is limited. The study includes only one artistic mural and three commercial murals for comparative analysis. Such a small dataset weakens the validity and persuasiveness of the research findings.

2.The rigor of the simulation process is somewhat lacking. It is unclear whether factors such as different weather conditions affecting visual perception, or the position and movement of observers, have been taken into account. These aspects appear to be overlooked in the simulation process.

3.There is a lack of recent references. It is recommended to include more references from the past two years to improve the timeliness and academic relevance of the study.

Author Response

Dear Reviewer,

Thank you for your time and valuable comments. We hope our responses will clear up your doubts and that you will be satisfied. We have modified the article according to your suggestions.

The overall research framework of the paper is relatively clear. It proposes a practically applicable analytical frame focusing on the relationship between mural content and illumination, with a strong integration of images and data. However, the paper still has the following issues, and revisions are recommended:

1.The sample size is limited. The study includes only one artistic mural and three commercial murals for comparative analysis. Such a small dataset weakens the validity and persuasiveness of the research findings.

We agree with your opinion. The more examples analysed in science, the better. However, in this case, the research conducted at these two locations provides a basis for concluding. An artistic mural is usually durable. Regardless of its content or location, its lighting should be tailored to the content. Analysing a larger number of artistic murals would yield no different conclusion than the one we have presented, because everyone will be different.

In the case of commercial murals, which change frequently, different locations, surfaces, viewing points, and directions would yield more data. We are sure that the conclusions would be the same: the luminous flux of light sources should be regulated to ensure the appropriate luminance level, and the distribution of illuminance and luminance should be considered when creating the composition for commercial murals. We analysed six real murals in various configurations on these three walls and one computer simulation.

2.The rigor of the simulation process is somewhat lacking. It is unclear whether factors such as different weather conditions affecting visual perception, or the position and movement of observers, have been taken into account. These aspects appear to be overlooked in the simulation process.

Thank you for your valuable feedback. We only conducted the computer simulation for the first set of murals (Figure 4). This set also presents the actual measurement using a matrix luminance meter for three murals. For subsequent sets, as the murals changed, the data we presented are field measurements taken in good weather conditions. This is related to several aspects. Luminance levels depend on the material. For example, road and architectural lighting standards refer to "dry" objects and good weather conditions. We also analysed the average luminance level; we could not draw accurate conclusions in the case of poor atmospheric conditions (especially haze). Therefore, the measurements were taken to ensure good weather conditions. The same applies to the direction of observation – for object illumination, average luminance levels refer to the main viewing directions. This is closely related to the contrast between the illuminated object and the background, which can have different luminance from different directions. We treated the mural as an architectural object, hence the assumption that the measurement should be taken from the main viewing direction. Nevertheless, your comment is inspiring. For example, it is reasonable to assume that the luminous flux of lighting sources should be limited in the case of haze. However, this is a topic for another type of research.

We feel it is unnecessary to include this information in the article, but if, despite our explanations, you think otherwise, please let us know.

3. There is a lack of recent references. It is recommended to include more references from the past two years to improve the timeliness and academic relevance of the study.

We have added some reference items.

Author Response File: Author Response.pdf