  Remote sensing imagery, despite its broad applications in helping achieve
Sustainable Development Goals and tackle climate change, has not yet benefited
from the recent advancements of versatile, task-agnostic vision language models
(VLMs). A key reason is that the large-scale, semantically diverse image-text
dataset required for developing VLMs is still absent for remote sensing images.
Unlike natural images, remote sensing images and their associated text
descriptions cannot be efficiently collected from the public Internet at scale.
In this work, we bridge this gap by using geo-coordinates to automatically
connect open, unlabeled remote sensing images with rich semantics covered in
OpenStreetMap, and thus construct SkyScript, a comprehensive vision-language
dataset for remote sensing images, comprising 2.6 million image-text pairs
covering 29K distinct semantic tags. With continual pre-training on this
dataset, we obtain a VLM that surpasses baseline models with a 6.2% average
accuracy gain in zero-shot scene classification across seven benchmark
datasets. It also demonstrates the ability of zero-shot transfer for
fine-grained object attribute classification and cross-modal retrieval. We hope
this dataset can support the advancement of VLMs for various multi-modal tasks
in remote sensing, such as open-vocabulary classification, retrieval,
captioning, and text-to-image synthesis.
