Datasets of historical aerial photograph orthomosaics of Lassen Volcanic National Park, California (1941, 1952, 1966, 1973, 1998 and 2004)

This data release publishes datasets of historical aerial photograph orthomosaics covering areas within and surrounding Lassen Volcanic National Park, California. The historical imagery provides a high-resolution, spatially contiguous record of the park?s landscape across six dates ranging from 1941-2004. A total of 990 hard-copy aerial photographs taken in 1941, 1952, 1966, 1973, 1998, and 2004 were scanned at 800 dpi with an Epson Expression 12000XL. The 1941-1966 images are in black and white and scanned in 16-bit greyscale, and 1973, 1998 and 2004 are in color and scanned as 24-bit RGB. Like many historical aerial photograph collections, most of the flight and camera parameters were missing; Structure-from-Motion (SfM) software offers an efficient solution for orthorectifying images that lack these parameters. We used a SfM software called Agisoft Metashape Professional (v.1.6) to generate the orthomosaics for each image year, which were aligned with sets of reference Ground Control Points (GCPs). Average Root Mean Square Error (RMSE) ranged from 4.07-140 cm, and average reprojection errors ranged from 0.56-0.78 meters. Each orthomosaic metadata file contains specific information on image processing, number of GCPs used and estimated error.

本数据集发布了覆盖加利福尼亚州拉森火山国家公园及其周边区域的历史航空摄影正射镶嵌数据集。这批历史影像提供了1941年至2004年间共6个时间节点下该公园景观的高分辨率、空间连续的观测记录。本次共扫描了1941、1952、1966、1973、1998及2004年拍摄的990张纸质航空照片，扫描设备为爱普生（Epson）Expression 12000XL扫描仪，扫描分辨率为800dpi。1941年至1966年的影像为黑白影像，采用16位灰度模式扫描；1973、1998及2004年的影像为彩色影像，采用24位RGB色彩模式扫描。与多数历史航空摄影馆藏类似，本次数据集的多数飞行参数与相机参数均有缺失；运动恢复结构（Structure-from-Motion，SfM）软件可为缺乏此类参数的影像正射校正提供高效解决方案。我们采用名为Agisoft Metashape Professional（版本1.6）的SfM软件，为各年份的影像生成正射镶嵌图，并将其与多组参考地面控制点（Ground Control Points，GCPs）进行配准。平均均方根误差（Root Mean Square Error，RMSE）取值范围为4.07厘米至140厘米，平均重投影误差取值范围为0.56米至0.78米。每份正射镶嵌图的元数据文件均包含影像处理流程、所用地面控制点数量及估算误差的详细信息。