Coordinate shifting for large polygons
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- Dominant language
- JavaScript
- Stars
- 1k
- Forks
- 86
- PR merge metrics
- No merged PRs in 30d
Description
I am using geobuf for encoding and decoding large geojson polygons for my project and have noticed that there seems to be some sort of error introduced by the encoding that compounds over time. This can result in polygons that are highly inaccurate for large perimeters. I know you guys have an accuracy of 1e6, but I feel like that is not what is causing this. Any help would be greatly appreciated. I am encoding using python and decoding using javascript
The problem:
Results of encoding and decoding geojson seem to change coordinates for polygons with a large number of coordinates
Steps to reproduce:
Github won't let me attach .json files directly, so I have compressed them. One file represents the unencoded data and the other after encoding and decoding with geobuf
geojson.zip
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the two GeoJSON files in geojson.zip and compare the original with the encoded-then-decoded result, focusing on coordinate differences in the large polygon. Trace the Python encoding and JavaScript decoding paths for large coordinate sets. Done means the supplied polygon round-trips without cumulative coordinate shifting beyond the stated accuracy.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- javascript, python
- Domain
- data
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100