National Gravity and Magnetic Derivatives Customised for Data Analysis and Machine Learning

PurposeThis package comprises a set of 86 thematic grids (rasters) derived from national coverages of gravity and magnetic survey data. These datasets provide valuable information about the distribution of geological features, physical property variations, and the composition of the Earth's crust. All grids have been resampled to the same cell size, map extent, and projection to allow them to be integrated into predictive mapping and modelling workflows using machine learning. Users can download individual grids or the whole grid package. Input DataThe following Australian national datasets were used:1. 2019 Australian National Gravity Grids: Free Air Anomaly, Complete Bouguer Anomaly, De-trended Global Isostatic Residual, 400 m cell size (Lane et al., 2020).2. Total Magnetic Intensity (TMI) Grid of Australia 2019 - seventh edition Enhanced Products Package (Morse, 2020).ProcessingAll processing of the national grids were undertaken using Intrepid software. The following was performed on the input data:1. The grids were reprojected from GDA94 geodetic to Australian Albers (EPSG 3577).2. The grids were aligned to the same grid cell registration point and interpolated to fit within an 80 m cell size using a cubic spline method to ensure that the cell locations for all images are common.3. Various Fast Fourier Transforms (FFT) were applied to each grid (see ‘Grids_for_Machine_Learning_dataset_notes.pdf’).Metadata (all grids)· Datum: GDA94· Projection: Australian Albers (EPSG 3577)· Cell size: 80 m· File format: GeoTiff (.tif)Full data is available on request from [e-mail] - Quote eCat# 149130See the manifest document below for the full file listing

用途
本数据集套装包含86幅专题栅格 (raster)，源自全国重力与磁法测量数据的全国覆盖数据集。这些数据集可为地质特征分布、物性变化以及地壳组成提供宝贵的参考信息。所有栅格已统一重采样至相同像元尺寸、地图范围与投影坐标系，可集成至机器学习驱动的预测成图与建模工作流。用户可单独下载单幅栅格，或下载整套栅格数据集。

输入数据
本数据集采用以下澳大利亚全国数据集：
1. 2019年澳大利亚全国重力栅格：自由空气异常、完整布格异常、去趋势全球均衡残差，像元尺寸为400米（Lane等人，2020）。
2. 2019年澳大利亚总磁场强度 (Total Magnetic Intensity, TMI) 栅格——第七版增强产品套件（Morse，2020）。

处理流程
所有全国栅格的处理均通过Intrepid软件完成，具体操作如下：
1. 将栅格从GDA94大地基准面重投影至澳大利亚阿尔伯斯投影（EPSG 3577）。
2. 对齐所有栅格的像元注册点，并通过三次样条插值法将其统一至80米像元尺寸，确保所有栅格的像元位置完全一致。
3. 对每幅栅格应用多种快速傅里叶变换 (Fast Fourier Transform, FFT)，详细说明参见《Grids_for_Machine_Learning_dataset_notes.pdf》。

栅格元数据（所有栅格）
· 基准面：GDA94
· 投影：澳大利亚阿尔伯斯投影（EPSG 3577）
· 像元尺寸：80米
· 文件格式：GeoTiff（.tif）

完整数据集可通过向[e-mail]申请获取，请引用eCat# 149130。完整文件列表请参阅下述清单文档。