在许多方面，互联网只是一个极不协调的尝试，以记录我们的星球。每天都有数以亿计的照片上传到网上，描绘我们自己、我们的城市、我们的风景和我们的食物。然而，它们也是孤立的、完全不同的：很难从雪崩中筛选出任何有意义的东西。不过，谷歌和华盛顿大学的研究人员找到了一种方法，他们发明了一套强大的算法，可以自动将数百万张在线照片按时间顺序排列，从摩天大楼到冰川，应有尽有。互联网一端插上电源，另一端则是我们不断变化的世界的记录。他们称之为“延时采矿”

“我们现在几乎可以立即创造数千个时间间隔。”

里卡多·马丁·布鲁拉、大卫·盖洛普和史蒂文·M·M·沃克写道：“随着时间的推移，人们拍摄的数十亿张照片记录了超缓慢的变化。塞茨在一份记录他们工作的文件中说而在用数月或数年的时间来创建一个这样的延时之前，[通过我们的算法]我们现在几乎可以立即创建数千个覆盖地球上最受欢迎的地方的延时。”

<**all>The time-lapses show buildings being c***tructed in Las Vegas. (University of Washington/Creative Comm***) </**all> <**all>They also reveal changes in the natural world, such as the retreat of the Briksdal**reen Glacier in Norway. (University of Washington/Creative Comm***) </**all> <**all>This time-lapse shows the snake-like movement of a sandbank in Thailand over time. (University of Washington/Creative Comm***) </**all>

One of the chief difficulties for the team was synthesizing a single focal point for their time-lapses. Fortunately, the sheer number of images available and our tendency to photograph the same landmarks from the same angles gave them a good starting point. They created a database of some 86 million publicly available photos from sites like Flickr and Picasa and began sorting them; first, creating clusters of different locati*** and then putting these sets into chronological order. For each time-lapse they selected a single reference image that would form the anchor point for the other photos, with their algorithms cropping, aligning, and color-fixing the images to create a single, **ooth time-lapse.

A time-lapse of 1,000 crowd-sourced photos took six hours to process

The team says that in the end they were left with 120,000 clusters, with 10,728 of these containing more than 300 images. From these candidates they selected clusters with more than 1,000 photos to process. "A typical time-lapse with 1,000 input posed photos takes about six hours to compute on a single machine," report the engineers. "While the algorithms can be optimized a lot more for efficiency, we point out that a few hours is negligible compared to the time period of several years it took to capture the photos." The end results are crowd-sourced time-lapses of the changing world, documented almost accidentally by milli*** of volunteers.