Quasi-HSL color space and its application: Sunlit and shaded component fractional cover estimation in vegetated ecosystem
Sunlit and shaded components are commonly present in both airborne and satellite remote sensing images. In vegetated ecosystems, shaded component often result from sunlight being obstructed by topographic relief or canopy structures, and shaded component may impact plant growth, leaf photosynthesis,...
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Elsevier
2024-12-01
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| Series: | International Journal of Applied Earth Observations and Geoinformation |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S156984322400654X |
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| author | Jia Tian Qingjiu Tian Suju Li Qianjing Li Sen Zhang Shuang He |
| author_facet | Jia Tian Qingjiu Tian Suju Li Qianjing Li Sen Zhang Shuang He |
| author_sort | Jia Tian |
| collection | DOAJ |
| description | Sunlit and shaded components are commonly present in both airborne and satellite remote sensing images. In vegetated ecosystems, shaded component often result from sunlight being obstructed by topographic relief or canopy structures, and shaded component may impact plant growth, leaf photosynthesis, and ultimately carbon sequestration. To accurately estimate the fractional cover of the shaded and sunlit components, including both green and non-green vegetation within vegetated ecosystems, a novel method called the quasi-Hue-Saturation-Lightness (quasi-HSL) method is proposed in this study. Inspired by the RGB to HSL conversion, this method utilizes near-infrared, green, and red bands to compute hue (and normalized hue), saturation, and lightness. Subsequently, two indices, namely Hue-Lightness Index (HLI) and Saturation-Lightness Index (SLI), are introduced to construct a triangular space for estimating the fractional cover of the three components. Through unmanned aerial vehicle field experiments conducted in two forested areas, the accuracy of fractional cover estimation for three components reaches an R2 value of 0.50–0.67. Furthermore, this fractional cover estimation approach can be extended to a four-component estimation, including sunlit green vegetation, sunlit non-green vegetation, shaded green vegetation, and shaded non-green vegetation. With this detailed fractional cover estimation in vegetated area, the fractional vegetation coverage can be retrieved. Cross-validated with the fractional vegetation coverage retrieved by NDVI, the accuracy reaches R2 = 0.92. The advantages of the proposed method are (1) estimating fractional cover of shaded component without blue band, which is easily impacted by atmospheric conditions and sensor performance, and (2) differentiating the sunlit green and non-green vegetation components in the vegetated ecosystem. |
| format | Article |
| id | doaj-art-ed3490e45b3d4c95b564f0f3f1145960 |
| institution | Kabale University |
| issn | 1569-8432 |
| language | English |
| publishDate | 2024-12-01 |
| publisher | Elsevier |
| record_format | Article |
| series | International Journal of Applied Earth Observations and Geoinformation |
| spelling | doaj-art-ed3490e45b3d4c95b564f0f3f11459602024-12-19T10:52:56ZengElsevierInternational Journal of Applied Earth Observations and Geoinformation1569-84322024-12-01135104298Quasi-HSL color space and its application: Sunlit and shaded component fractional cover estimation in vegetated ecosystemJia Tian0Qingjiu Tian1Suju Li2Qianjing Li3Sen Zhang4Shuang He5School of Instrumentation and Optoelectronic Engineering, Beihang University, Beijing 100191, China; Key Laboratory of Precision Opto-Mechatronics Technology, Ministry of Education, Beihang University, Beijing 100191, China; International Institute for Earth System Science, Nanjing University, Nanjing 210023, ChinaInternational Institute for Earth System Science, Nanjing University, Nanjing 210023, China; Corresponding authors.Key Laboratory of Emergency Satellite Engineering and Application, Ministry of Emergency Management, Beijing 100124, China; Corresponding authors.International Institute for Earth System Science, Nanjing University, Nanjing 210023, ChinaInternational Institute for Earth System Science, Nanjing University, Nanjing 210023, ChinaInternational Institute for Earth System Science, Nanjing University, Nanjing 210023, ChinaSunlit and shaded components are commonly present in both airborne and satellite remote sensing images. In vegetated ecosystems, shaded component often result from sunlight being obstructed by topographic relief or canopy structures, and shaded component may impact plant growth, leaf photosynthesis, and ultimately carbon sequestration. To accurately estimate the fractional cover of the shaded and sunlit components, including both green and non-green vegetation within vegetated ecosystems, a novel method called the quasi-Hue-Saturation-Lightness (quasi-HSL) method is proposed in this study. Inspired by the RGB to HSL conversion, this method utilizes near-infrared, green, and red bands to compute hue (and normalized hue), saturation, and lightness. Subsequently, two indices, namely Hue-Lightness Index (HLI) and Saturation-Lightness Index (SLI), are introduced to construct a triangular space for estimating the fractional cover of the three components. Through unmanned aerial vehicle field experiments conducted in two forested areas, the accuracy of fractional cover estimation for three components reaches an R2 value of 0.50–0.67. Furthermore, this fractional cover estimation approach can be extended to a four-component estimation, including sunlit green vegetation, sunlit non-green vegetation, shaded green vegetation, and shaded non-green vegetation. With this detailed fractional cover estimation in vegetated area, the fractional vegetation coverage can be retrieved. Cross-validated with the fractional vegetation coverage retrieved by NDVI, the accuracy reaches R2 = 0.92. The advantages of the proposed method are (1) estimating fractional cover of shaded component without blue band, which is easily impacted by atmospheric conditions and sensor performance, and (2) differentiating the sunlit green and non-green vegetation components in the vegetated ecosystem.http://www.sciencedirect.com/science/article/pii/S156984322400654XPixel unmixingFractional coverShadowVegetated areaQuasi-HSL |
| spellingShingle | Jia Tian Qingjiu Tian Suju Li Qianjing Li Sen Zhang Shuang He Quasi-HSL color space and its application: Sunlit and shaded component fractional cover estimation in vegetated ecosystem International Journal of Applied Earth Observations and Geoinformation Pixel unmixing Fractional cover Shadow Vegetated area Quasi-HSL |
| title | Quasi-HSL color space and its application: Sunlit and shaded component fractional cover estimation in vegetated ecosystem |
| title_full | Quasi-HSL color space and its application: Sunlit and shaded component fractional cover estimation in vegetated ecosystem |
| title_fullStr | Quasi-HSL color space and its application: Sunlit and shaded component fractional cover estimation in vegetated ecosystem |
| title_full_unstemmed | Quasi-HSL color space and its application: Sunlit and shaded component fractional cover estimation in vegetated ecosystem |
| title_short | Quasi-HSL color space and its application: Sunlit and shaded component fractional cover estimation in vegetated ecosystem |
| title_sort | quasi hsl color space and its application sunlit and shaded component fractional cover estimation in vegetated ecosystem |
| topic | Pixel unmixing Fractional cover Shadow Vegetated area Quasi-HSL |
| url | http://www.sciencedirect.com/science/article/pii/S156984322400654X |
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