locationtech / locationtech/jts
Small buffer of a polygon returns an empty geometry
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Description
I'm working with a precision model with a fixed scale of 10000. When doing a buffer operation of +-0.001 sometimes it returns an empty geometry when it isn't the correct result.
I have replicated a couple of them in the JTS Test Builder from the 1.19.0 release, setting it to the precision model I use in code.
"POLYGON ((-1.1261 35.3205, 77.1866 37.8173, 78.3127 2.4968, 0 0, -1.1261 35.3205))"
Doing the default buffer of -0.001 returns an empty geometry.

"POLYGON ((28.3065 22.0679, 33.2298 29.772, 49.9274 19.1013, 45.0042 11.3973, 28.3065 22.0679))"
Doing a buffer of 0.001 with the bevel join returns an empty geometry

I have not had this issue using values of over 0.01 in absolute value or using a finer grid size.
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Research direction
Reproduce the issue in the JTS Test Builder from the 1.19.0 release using a fixed precision scale of 10000 and the two polygons in the report. Test buffers of ±0.001, including the bevel join case, and compare them with larger values or a finer grid; done means these valid operations no longer incorrectly return empty geometries.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- java
- Domain
- computer-graphics
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 40/100