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. 2023 Jan 6;13(1):260.
doi: 10.1038/s41598-022-27183-x.

Dynamic grass color scale display technique based on grass length for green landscape-friendly animation display

Affiliations

Dynamic grass color scale display technique based on grass length for green landscape-friendly animation display

Kojiro Tanaka et al. Sci Rep. .

Abstract

Public displays, such as liquid crystal displays (LCDs), are often used in urban green spaces. However, these display devices often tarnish the green landscape of urban green spaces due to their artificial materials. We previously proposed a green landscape-friendly grass animation display that dynamically controls the grass color pixel by pixel. The grass color is changed by moving a green grass length in yellow grass, and the grass animation display runs simple animations using grayscale images. In our previous study, the color scale is subjectively mapped to the green grass length. However, this method fails to display the grass colors corresponding to the color scale based on objective evaluations. Herein, we introduce a dynamic grass color scale display technique based on the grass length. We develop a grass color scale setting procedure to map the grass length to the five-level color scale through image processing. In the outdoor experiment of the grass color scale setting procedure, the color scale corresponds to the green grass length based on a viewpoint. Finally, we demonstrate a grass animation display to show the animations with the color scale using experimental results.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
Concept of green landscape-friendly animation display in urban green space. The grass animation display runs a weather forecast application while preserving the green landscape of the urban green space. The background photo was captured at University of Tsukuba. The umbrella material was used in SKY’s animation (https://pata2.jp). This figure was created using Autodesk Maya version 2023 (https://www.autodesk.com/products/maya/features) and Serif Affinity Designer version 1.10.0 (https://affinity.serif.com/en-us/).
Figure 2
Figure 2
Concept of displaying grass color corresponding to color scale. (a) A grass color scale system allows a grass animation display to show an animation using grayscale images. The color scale corresponds to a green grass length. (b) Green grass length of the grass pixel corresponding to the color scale is determined using a grass color scale setting procedure. The results are reflected in the grass color scale system to show the animation on the grass animation display. This figure was created using Autodesk 3ds Max version 2021 (https://www.autodesk.com/products/3ds-max/features) and Serif Affinity Designer version 1.10.0 (https://affinity.serif.com/en-us/).
Figure 3
Figure 3
Design of grass pixel system. (a) A grass pixel is developed using a linear actuator system operated by a motor. Artificial green and yellow grass is planted on a top surface of a 3D printed pin and a surface plate, respectively. (b) The surface plate has slits to move the artificial green grass in and out of the artificial yellow grass. (c) The grass pixel displays multiple grass colors based on an area ratio of the artificial green and yellow grass through spatial additive mixing. This figure was created using Autodesk 3ds Max version 2021 (https://www.autodesk.com/products/3ds-max/features) and Serif Affinity Designer version 1.10.0 (https://affinity.serif.com/en-us/).
Figure 4
Figure 4
Overview of grass color scale setting procedure. (a) The grass color of a grass pixel is measured as a CIELAB value through image processing. (b) Measured grass color values are compared with target grass color values to map the grass length of the grass pixel to a color scale with five levels. (c) To calculate the target grass color value, tn suitable for Gn is determined so that ΔE00(G0,P(tn)) is (n/4)·ΔE00(G0,G4). This figure was created using Serif Affinity Designer version 1.10.0 (https://affinity.serif.com/en-us/).
Figure 5
Figure 5
Experimental environment of grass color scale setting procedure. (a) A digital camera was located at multiple positions based on the viewer’s height, a distance and a horizontal angle between a viewer and a grass pixel. (b) The grass pixel was developed for our experiment of the grass gradation scale setting procedure. (c) The grass color of the grass pixel was measured as a CIELAB value at 0.75 mm intervals. This figure was created using Serif Affinity Designer version 1.10.0 (https://affinity.serif.com/en-us/).
Figure 6
Figure 6
Examples of ddtΔE00(G0,P(t)). (a, b) ΔE00(G0,P(t)) can simply increase and G1,G2 and G3 can be uniquely obtained at (h,d,θ)=(1.2,1.0,0) and (1.2, 3.0, 0) because these resutls of ddtΔE00(G0,P(t)) were positive in the range of 0t1. This figure was created using Serif Affinity Designer version 1.10.0 (https://affinity.serif.com/en-us/) and Mathematica version 13.1.0.0 (https://www.wolfram.com/mathematica/?source=nav).
Figure 7
Figure 7
Examples of experimental results of grass color scale setting procedure. (a, b) Results at (h,d,θ)=(1.2,1.0,0) and (1.2, 3.0, 0) were successful to map the green grass length corresponding to the color scale. (c, d) Results at (h,d,θ)=(1.2,3.0,90) and (1.6, 2.0, 60) failed due to the influence of the slits of the grass pixel. This figure was created using Serif Affinity Designer version 1.10.0 (https://affinity.serif.com/en-us/) and Matplotlib version 3.2.2 (https://matplotlib.org).
Figure 8
Figure 8
Simple experiments on repeatability and reliability of grass pixel. (a, b) The camera height and the distance between the camera and the grass pixel were fixed. The horizontal angles between them were 0, 30, 60, and 90. The experiments were conducted the playground in the University of Tsukuba under natural sunlight from 10:00 a.m. to 2:00 p.m. (c) Since most of the measured grass color values were within the blue ellipsoid of the color tolerance of the reference grass color value for each camera position, the experimental results revealed that the grass pixel can show the grass color stably with the grass length. This figure was created using Serif Affinity Designer version 1.10.0 (https://affinity.serif.com/en-us/) and Matplotlib version 3.2.2 (https://matplotlib.org).
Figure 9
Figure 9
Animation system of a grass animation display used for demonstration. (a) A 3×3 pixels grass animation display was developed using nine grass pixels. (b) A keyframe animation system was adopted to play an animation on the grass animation display. A green length of a grass pixel was changed according to input levels of a color scale in keyframe order. This figure was created using Serif Affinity Designer version 1.10.0 (https://affinity.serif.com/en-us/).
Figure 10
Figure 10
Demonstration results of a 3×3 pixels grass animation display using results of grass color scale setting experiments at (h,d,θ)=(1.7,2.0,0). (a) The response time to change the grass pixel from minimum and maximum of the grass color scale was 1.0 [s]. (b) Four animations of (i) path of letter N, (ii) cross, (iii) rain, and (iv) wave were played on the pixels grass animation display. This figure was created using Serif Affinity Designer version 1.10.0 (https://affinity.serif.com/en-us/).

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