mapbox / mapbox/rio-cloudmask

Handle absence of TIRS Band 10

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bug
Dominant language
Python
Stars
55
Forks
12
PR merge metrics
No merged PRs in 30d

Description

When the TIRS band 10 is all-zero, as is the case with e.g. [LC80460282016097LGN00](http://landsat-pds.s3.amazonaws.com/L8/046/028/LC80460282016097LGN00/index.html), the equations 7&8 are filled with nans

```
/Users/mperry/env/mapbox35/lib/python3.5/site-packages/numpy/lib/nanfunctions.py:1001: RuntimeWarning: All-NaN slice encountered
warnings.warn("All-NaN slice encountered", RuntimeWarning)
```

Which leads to the masking of the entire scene, as if there were 100% clouds.

The fmask algorithm is capable of dealing with the absence of a thermal band. We just need to
- [ ] figure out why some seemingly arbitrary scenes have blank thermal bands (is this a known TIRS issue @celoyd?)
- [ ] adjust the implementation to fallback to a non-thermal mode.

Contributor guide

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First steps

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the failure with LC80460282016097LGN00 and inspect the fmask handling of an all-zero TIRS band and the equations 7 and 8 path. Done means scenes with an absent thermal band use a non-thermal fallback instead of producing NaNs and masking the entire scene.

Written by the indexing model from the issue text.

Assessment

Tech stack
numpy, python
Domain
computer-vision, data
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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