Africa tree cover map
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Data description This file is a 100 m resolution map of % tree canopy cover per pixel for Africa in 2019. Tree cover values range from 0-100 % and nodata areas are masked as -1. The map is derived from predictions of tree cover using 3 m PlanetScope imagery, which were resampled to 1 m, and then aggregated to 100 m. Predictions at 1 m resolution (or anything between 1 and 100 m) are available on request. The image data was processed from raw scenes into merged 1x1 degree mosaics. Differences in the quality of raw scenes and processed mosaics can lead to artifacts in the predicted tree cover, visible as seamlines along scene or mosaic edges. Therefore the current version of this map should not be seen as a final product representing the exact tree cover at each location, but as a proof of concept of what is possible with PlanetScope data. The main benefit of this map is the inclusion of cover from scattered single trees in sparse cover areas such as savannahs. Here it can serve as a complement to existing forest cover maps to extend the mapping to include non-forest trees. License This tree cover map is made freely available for non-commercial purposes. All usage of the data must be attributed and should be cited with the paper citation. Please see the NICFI license for full terms of usage, available at: https://assets.planet.com/docs/Planet_ParticipantLicenseAgreement_NICFI.pdf Version differences We recommend to always use the latest version. We are continuously improving the quality and consistency of the tree cover mapped, and are expecting to release regular version updates, based on an improved model and mosaics. We also plan to release different years in the future. Version 0.1: ps_africa_treecover_2019_100m_v0.1 This version was used for the analyses in the paper. It used the first version of the mosaics, which suffered from the inclusion of lower-quality scenes and missing data. Known issues - missing data coverage: incomplete mosaics and mosaics missing scenes - inconsistent predictions between mosaics: visible mosaic edges, see Zimbabwe - underprediction in very sparse cover areas - overprediction of cover in denser shrublands - overprediction (artifacts) in mountains, desert dunes, croplands and some urban areas - flowering trees in closed forests are mapped as gaps - occasional confusion between understory or shrubs and trees in wood- and shrublands Version 1.0: ps_africa_treecover_2019_100m_v1.0 This is the latest version available as of March 2023. It is based on improved mosaics and a revised model, leading to better consistency both between and within mosaics. However the current model underpredicts solid tree cover in shrublands and woodlands, leading to an overall underprediction in lower rainfall areas. Improvements over v0.1: - improved mosaic quality - reduced artifacts in croplands and urban areas (though some remain) - better consistency of forest area mapping - better detection rate of small trees in dry areas Known issues - underprediction of tree clusters in shrublands - some (few) false predictions of small trees in dry areas - occasional inconsistent predictions within mosaics: seamlines along scene edges - areas of underprediction in dense tropical forest due to lower quality scenes, see DRC - overprediction (artifacts) in mountains, and occasionally desert dunes - flowering trees in closed forests are mapped as gaps - occasional confusion between understory or shrubs and trees in wood- and shrublands - trees without leaves may not be mapped correctly
数据说明 本文件为2019年非洲地区100米分辨率的每像素树冠覆盖率（tree canopy cover）百分比地图。树冠覆盖率数值区间为0-100%，无数据区域被掩膜为-1。 该地图基于3米分辨率的PlanetScope影像开展树冠覆盖率预测生成，先将预测结果重采样至1米分辨率，再聚合为100米分辨率。1米分辨率（或1至100米间任意分辨率）的预测结果可按需申请获取。 影像数据经处理从原始场景拼接为1×1度的镶嵌图。原始场景质量差异与镶嵌处理过程可能导致预测树冠覆盖率出现伪影，表现为场景或镶嵌图边缘的接缝线。因此，本地图当前版本不应被视为精准反映各区域实际树冠覆盖率的最终产品，仅作为PlanetScope数据应用可行性的概念验证。 本地图的核心优势在于可覆盖稀树草原等稀疏植被区域内零散单株树木的覆盖率统计，可作为现有森林覆盖地图的补充，将植被测绘范围扩展至非森林树木范畴。 授权许可 本树冠覆盖地图免费开放非商业用途。使用该数据时必须注明来源，并引用对应论文。完整使用条款请参阅NICFI许可协议，详情见：https://assets.planet.com/docs/Planet_ParticipantLicenseAgreement_NICFI.pdf 版本差异说明 建议始终使用最新版本。团队正持续优化树冠覆盖测绘的质量与一致性，计划基于改进后的模型与镶嵌图定期发布版本更新，未来还将推出不同年份的数据集。 版本0.1：ps_africa_treecover_2019_100m_v0.1 本版本用于论文中的分析工作，采用首批镶嵌图，存在低质量场景混入与数据缺失问题。已知问题包括： - 数据覆盖不全：镶嵌图不完整、存在场景缺失情况 - 镶嵌图间预测结果不一致：可见镶嵌边缘，以津巴布韦区域为例 - 极稀疏植被区域存在预测值偏低问题 - 较密集灌丛区域存在覆盖率预测偏高问题 - 山地、沙漠沙丘、农田及部分城区存在预测伪影（偏高） - 封闭森林中的开花树木被误绘为植被空白区 - 木本与灌丛区域中，林下植被或灌木与树木偶尔存在识别混淆 版本1.0：ps_africa_treecover_2019_100m_v1.0 本版本为截至2023年3月的最新可用版本，基于改进后的镶嵌图与修订后的模型构建，提升了镶嵌图间与镶嵌图内部的一致性。但当前模型仍存在灌丛与林地内连片树木覆盖预测偏低的问题，导致低降雨区域整体覆盖率预测偏低。相较于v0.1的改进点包括： - 镶嵌图质量提升 - 农田与城区的伪影减少（仍存在部分残留） - 森林区域测绘一致性提升 - 干旱区域小型树木的检出率提升 已知问题包括： - 灌丛内连片树群预测偏低 - 干旱区域存在少量小型树木的误预测 - 镶嵌图内部偶尔存在预测结果不一致：场景边缘出现接缝线 - 受原始场景质量限制，热带稠密森林区域存在预测偏低问题，以刚果（金）区域为例 - 山地及偶尔出现的沙漠沙丘区域存在预测伪影（偏高） - 封闭森林中的开花树木被误绘为植被空白区 - 木本与灌丛区域中，林下植被或灌木与树木偶尔存在识别混淆 - 无叶树木可能无法被正确识别
