Photogrammetric scans of aerial photographs of North American glaciers, 1974. Roll 1 tiffs

Introduction: Between 1958 and 1999, Austin Post led the USGS collection of aerial imagery of North American glaciers. These images are primarily vertical stereo black and white images, although single oblique images, as well as color images have been collected. The glaciers of North America were the subjects, and the digital products made available here serve to document the changes that have occurred to the glaciers over the past 5 decades. The purpose of this project is to preserve the data contained within these film images in a digital format for future analysis of North American glacier change. File Layout: 1. The first level contains an overall data set of image metadata from 1964 - 1997 (nagapData.csv) and an R script (searchData.R) with instructions on how to search and subset the data. fileLayout.pdf shows the file structure and folder contents visually. There are also three kml files with flight path information by decade. 2. The second level is the year in which the pictures were taken. There are 32 years with images from 1964 – 1997. The majority of these folders are jpegs with notes provided by Austin Post. They also contain a year-specific csv (YYYY.csv) that contains image metadata for the entire year (date, roll numbers, location name, longitude, latitude, altitude, media, and comments). The overall data set (nagapData.csv) is the aggregate of each individual “YYYY.csv” file. 3. The glacier photos are located at the third level (this level). The folders at this level are distinguished by camera roll number (1, 2, etc.), and image type (thumbnail, jpeg, or tif); some also contain fiducial and oblique image folders. This level primarily contains image files of aerial photos as either thumbnails, jpegs, or tifs. It also includes a csv with image metadata specific to each roll (date, roll numbers, location name, longitude, latitude, altitude, media, and comments), a text file (info.txt) with camera specifications unique to each image, and a text file (histo.txt or matchReport.txt) with color information and scanner specifications unique to each image.## 介绍 1958年至1999年间，奥斯汀·波斯特主持了美国地质调查局（United States Geological Survey, USGS）的北美冰川航空影像采集工作。本次采集的影像以垂直立体黑白航空影像为主，同时也收录了单张倾斜影像与彩色影像。本数据集以北美冰川为研究对象，此处公开的数字化成果旨在记录近50年来北美冰川的变化情况。本项目的核心目标是将这些胶片影像中的数据以数字化格式永久保存，以供后续开展北美冰川变化相关研究使用。 ## 文件布局 1. 一级目录包含1964年至1997年的全局影像元数据集（nagapData.csv），以及用于指导数据检索与子集筛选的R脚本（searchData.R）。`fileLayout.pdf`以可视化形式展示了整体文件结构与目录内容，此外还包含3个按年代划分飞行路径信息的KML（Keyhole Markup Language）文件。 2. 二级目录对应影像拍摄年份。本数据集涵盖1964年至1997年的32个拍摄年份。多数二级目录内包含奥斯汀·波斯特撰写标注说明的JPEG图像文件，同时还包含对应年份的专属元数据文件（YYYY.csv），该文件存储了全年所有影像的元数据，包括拍摄日期、航摄卷号、地点名称、经度、纬度、海拔、介质类型与备注信息。全局数据集nagapData.csv实为所有单个"YYYY.csv"文件的汇总。 3. 三级目录即本层级，存储冰川航空影像。该层级下的目录以航摄卷号（1、2等）与影像类型（缩略图、JPEG或TIFF（Tagged Image File Format））进行区分，部分目录还包含框标影像与倾斜影像子目录。本层级主要存储航空影像的缩略图、JPEG或TIFF格式文件，同时还包含每个航摄卷专属的影像元数据CSV文件（包含拍摄日期、航摄卷号、地点名称、经度、纬度、海拔、介质类型与备注信息）、存储单张影像专属相机参数的文本文件（info.txt），以及存储单张影像专属色彩信息与扫描仪参数的文本文件（histo.txt或matchReport.txt）。