Data publication: Underground hyperspectral outcrop scanning for automated mine-face mapping — the Lithium deposit of Zinnwald/Cínovec

As part of a project on the development of hyperspectral scanning to support geological mapping in underground mines, we acquired hyperspectral data from three adjacent outcrops of Sn-W-Li greisen rocks in the visitor’s mine of Zinnwald, Germany. The hyperspectral scans were pre-processed and then back-projected onto photogrammetric, three-dimensional digital outcrop models resulting in so-called "hyperclouds". The here presented hyperclouds from the three outcrops (Z1, Z2, and Z3) contain the following attributes: ZX_Absorbance.ply<br> RGB colours: Mica/clay-zinnwaldite-topaz abundance based on absorbance (1 – hull-corrected reflectance) at 2200 nm (red), 2250 nm (green), and 2085 nm (blue)<br> Scalars: Absorbance at 2086.88 nm, 2160.69 nm, 2197.53 nm, 2209.8 nm, 2252.7 nm, and 2338.31 nm ZX_Iron.ply<br> RGB colours: Composite (Fe3+ Fe2+ FeOH) iron index (red: 600/570 nm, green:(920 nm + 1650 nm)/ (1035 nm 1230 nm), blue: (2230 nm 2290 nm)/(2245 nm + 2260 nm)<br> Scalars: Fe3+ = 600/570 nm, Fe2+ = (920 nm + 1650 nm)/ (1035 nm + 1230 nm), FeOH = (2230 nm + 2290 nm)/(2245 nm + 2260 nm) ZX_MNF.ply<br> RGB colours: Minimum noise fraction false colour (red: band 4, green: band 7, blue: band 5)<br> Scalars: Minimum noise fraction bands 4, 7, 5) ZX_RGB_mineralogy_Li.ply<br> RGB colours: True colour RGB from photogrammetric outcrop model<br> Scalars: Mineral abundances derived by combining sample mineralogy from quantitative XRD measurements and hyperspectral unmixing approaches: Quartz/Feldspar, Zinnwaldite, Muscovite/Illite, Kaolinite, Topaz, Lithium (by multiplying the zinnwaldite abundance by its average lithium content of 1.7%)

本数据集源自一项用于支撑地下矿井地质填图的高光谱扫描（hyperspectral scanning）技术开发项目，我们在德国津瓦尔德游客矿井的三处相邻锡-钨-锂云英岩（Sn-W-Li greisen rocks）露头采集了高光谱数据（hyperspectral data）。对采集得到的高光谱扫描数据进行预处理后，将其反投影至摄影测量三维数字露头模型中，由此生成所谓的“超云（hyperclouds）”数据集。本次公开的三处露头（编号Z1、Z2、Z3）对应的超云数据包含以下属性：
1. ZX_Absorbance.ply：
RGB配色：基于2200 nm（红色通道）、2250 nm（绿色通道）与2085 nm（蓝色通道）处的吸光度（absorbance，即1减去包络线校正反射率（hull-corrected reflectance））生成的云母/黏土-锂云母（zinnwaldite）-黄玉（topaz）丰度可视化结果；
标量属性：2086.88 nm、2160.69 nm、2197.53 nm、2209.8 nm、2252.7 nm及2338.31 nm处的吸光度值。
2. ZX_Iron.ply：
RGB配色：复合（Fe³+、Fe²+、FeOH）铁指数（iron index）可视化结果（红色通道：600/570 nm，绿色通道：(920 nm + 1650 nm)/(1035 nm + 1230 nm)，蓝色通道：(2230 nm + 2290 nm)/(2245 nm + 2260 nm)）；
标量属性：Fe³+ = 600/570 nm、Fe²+ = (920 nm + 1650 nm)/(1035 nm + 1230 nm)、FeOH = (2230 nm + 2290 nm)/(2245 nm + 2260 nm)。
3. ZX_MNF.ply：
RGB配色：最小噪声分离（Minimum Noise Fraction, MNF）假彩色合成结果（红色通道：波段4，绿色通道：波段7，蓝色通道：波段5）；
标量属性：最小噪声分离波段4、7、5对应数值。
4. ZX_RGB_mineralogy_Li.ply：
RGB配色：源自摄影测量露头模型的真实色彩RGB结果；
标量属性：通过结合定量X射线衍射（X-ray diffraction, XRD）测量的样品矿物学数据与高光谱解混（hyperspectral unmixing）方法得到的矿物丰度，包括石英（Quartz）/长石（Feldspar）、锂云母（Zinnwaldite）、白云母（Muscovite）/伊利石（Illite）、高岭石（Kaolinite）、黄玉（Topaz），以及锂元素丰度（通过锂云母丰度乘以其平均锂含量1.7%计算得到）。