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update images
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valentina-s committed Jul 7, 2024
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Expand Up @@ -18,7 +18,7 @@ We use three workflows to batch process image pairs for glacier surface velocity
### 1. `image_correlation_pair`
This workflow calls a Python script (image_correlation.py) that runs autoRIFT on a pair of spatially overlapping [Sentinel-2 L2A](https://docs.sentinel-hub.com/api/latest/data/sentinel-2-l2a/) images. It requires the [product names](https://sentiwiki.copernicus.eu/web/s2-products) of the two images. The images are downloaded from aws using the [Element 84 Earth Search API](https://element84.com/earth-search/). Only the near infrared band (NIR, B08) is used which has a spatial resolution of 10 m. autoRIFT is used to perform image correlation. Search distances are scaled with temporal baseline assuming a maximum surface velocity of 1000 m/yr, so images acquired farther apart in time take longer to process. Surface velocity maps are saved as geotifs and uploaded as [Github Artifacts](https://docs.github.com/en/actions/using-workflows/storing-workflow-data-as-artifacts).

![plot](./images/input_images.png)
![plot](https://github.com/uwescience/SciPy2024-GitHubActionsTutorial/blob/main/glacier_image_correlation/images/input_images.png)

### 2. `batch_image_correlation`
This workflow can be used to create surface velocity maps from many pairs of Sentinel-2 images. Required inputs include maximum cloud cover percent, start month (recommend >=5 to minimize snow cover), end month (recommend <=10 to minimize snow cover), and number of pairs per image, e.g.:
Expand All @@ -31,7 +31,7 @@ Only the first suitable image is selected for each month. Once image pairs are i
### 3. `summary_statistics`
This workflow downloads all of the velocity maps created during a `batch_image_correlation` run and uses them to calculate and plot median velocity, standard deviation of velocity, and valid pixel count across all velocity maps. The summary statistics plot is uploaded as a Github Artifact.

![plot](./images/velocity_summary_statistics.png)
![plot](https://github.com/uwescience/SciPy2024-GitHubActionsTutorial/blob/main/glacier_image_correlation/images/velocity_summary_statistics.png)


## Acknowledgements
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