AmsterTime: A Visual Place Recognition Benchmark Dataset for Severe Domain Shift

<strong>AmsterTime</strong> dataset offers a collection of 2,500 well-curated images matching the same scene from a street view matched to historical archival image data from Amsterdam city. The image pairs capture the same place with different cameras, viewpoints, and appearances. Unlike existing benchmark datasets, AmsterTime is directly crowdsourced in a GIS navigation platform (Mapillary). In turn, all the matching pairs are verified by a human expert to verify the correct matches and evaluate the human competence in the Visual Place Recognition (VPR) task for further references.<br>The properties of the dataset are summarized as:1200+ license-free images from the Amsterdam City Archive, representing urban places in the city of Amsterdam, captured in the past century by many photographers.All archival queries are matched with street view images from Mapillary.All matches are verified by architectural historians and Amsterdam inhabitants.Image pairs are archival and street views capturing the same place with different cameras, time lags, structural changes, occlusion, viewpoint, appearance, and illuminations.The dataset exhibits a domain shift between query and the gallery due to significant difference between scanned archival and street view images.Two sub-tasks are created on the dataset:<strong>Verification</strong> is a binary classification (auxiliary) task to detect a pair of archival and street-view images of the same place. The verification task for AmsterTime dataset has all of the crowdsourced image pairs as positive labeled, where the same number of negative samples are generated by randomly pairing archival and street-view images summing up to a total of 2,462 pairs in the verification task.<strong>Retrieval</strong> is the main task corresponding to VPR, in which a given query image is matched with a set of gallery images. For the retrieval task, AmsterTime dataset offers 1231 query images where the leave-one-out set serves as the gallery images for each query.

<strong>AmsterTime</strong> 数据集收录了2500张经过精心筛选的图像对，每一对均对应阿姆斯特丹市的同一街景，分别由街景影像与历史档案影像构成。这些图像对拍摄自同一地点，但采用了不同的相机、视角与呈现效果。与现有基准数据集不同，AmsterTime 数据集的标注数据直接通过地理信息系统（Geographic Information System, GIS）导航平台（Mapillary）进行众包获取。此外，所有匹配对均经过人类专家核验，以确认匹配的准确性，同时可用于评估人类在视觉地点识别（Visual Place Recognition, VPR）任务中的胜任能力，为相关研究提供参考。

该数据集的特性总结如下：
1. 包含1200余张来自阿姆斯特丹城市档案馆的免授权使用图像，这些图像由多位摄影师于过去一个世纪拍摄，涵盖阿姆斯特丹市内多处城市地点；
2. 所有档案查询图像均与Mapillary平台提供的街景图像完成匹配配对；
3. 所有匹配对均由建筑史学者与阿姆斯特丹本地居民共同核验；
4. 每对图像分别为档案影像与街景影像，拍摄自同一地点，但存在相机参数、时间跨度、建筑结构变化、遮挡情况、视角、呈现效果与光照条件等多方面差异；
5. 由于扫描式档案影像与街景图像存在显著差异，该数据集的查询集与图库集之间存在明显的域偏移（domain shift）。

该数据集设置了两项子任务：
<strong>匹配验证（Verification）</strong>：这是一项二元分类辅助任务，旨在识别属于同一地点的档案影像与街景图像对。AmsterTime 数据集的验证任务中，所有众包获取的图像对均标记为正样本；同时通过随机配对档案影像与街景图像生成等量的负样本，最终验证任务共包含2462对图像。
<strong>图像检索（Retrieval）</strong>：这是对应视觉地点识别任务的核心子任务，即给定一张查询图像，将其与图库集图像进行匹配。针对检索任务，AmsterTime 数据集提供了1231张查询图像，且每个查询图像对应的图库集均采用留一法（leave-one-out）构建。