Photogrammetric scans of aerial photographs of North American glaciers, 1976

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.

Package 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 (this 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. 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) with color information unique to each image.

Introduction:

1958年至1999年间，Austin Post领导美国地质调查局（USGS）开展北美冰川航空影像的收集工作。这些影像以垂直立体黑白影像为主，但也涵盖单张倾斜影像及彩色影像。研究对象为北美的冰川，本平台提供的数字产品旨在记录过去50年间冰川发生的变化。该项目的核心目标是将胶片影像中蕴含的数据以数字格式留存，为未来北美冰川变化的分析研究提供支持。

Package Layout:

1.

一级目录包含1964-1997年的影像元数据总集（nagapData.csv）以及一个R脚本（searchData.R），该脚本附带数据搜索与子集化的操作说明。fileLayout.pdf文件以可视化方式呈现了整体文件结构与文件夹内容。此外，还有三个按十年划分的飞行路径信息KML文件。

2.

二级目录（当前层级）对应照片的拍摄年份。1964-1997年间共有32个年份存在可用影像。这些文件夹多数包含JPEG文件及Austin Post提供的注释，同时还包含一个年份专属的CSV文件（YYYY.csv），其中记录了全年影像的元数据（包括日期、卷号、位置名称、经度、纬度、海拔、介质类型及注释）。前述影像元数据总集（nagapData.csv）系各独立“YYYY.csv”文件的汇总结果。

3.

冰川照片位于三级目录。该层级的文件夹按相机卷号（1、2等）与影像类型（缩略图、JPEG或TIFF）分类；部分文件夹还包含基准（fiducial）影像文件夹及倾斜影像文件夹。此层级主要存放航空照片的影像文件，格式涵盖缩略图、JPEG或TIFF。此外，还包含每个卷专属的影像元数据CSV文件（含日期、卷号、位置名称、经度、纬度、海拔、介质类型及注释）、记录每张影像专属相机参数的文本文件（info.txt），以及记录每张影像专属色彩信息的文本文件（histo.txt）。