TIN Surfaces and Gradings Corrupted After Large Coordinate Move — Notes from a New User
As a new BricsCAD user setting up my first civil model, I initially built everything at full UTM‑scale coordinates (in my case, MGA in Australia). That meant the geometry sat hundreds of kilometres from the origin. I soon noticed what I found out to be large‑coordinate issues which apparently is common: snapping felt vague, some commands behaved unpredictably and noticeable Boolean tool errors.
Upon further reading and realising modelling so far from the origin was an issue, I later moved the model back to the origin. This resulted in all TIN surfaces and gradings became corrupted. Some TINs developed long “tails,” others lost faces, and one surface disappeared completely. Several gradings also collapsed or failed to regenerate. Result was to delete all gradings and TINS.
From what I can tell, the problem comes from floating‑point precision loss when civil objects are moved large distances. The triangulation becomes unstable and the surface can’t rebuild correctly.
Recommended work around:
Create 2 files, first one the master file in UTM/MGA (or equivalent national grid)
Second detailed file, build model near the origin.
XREF the detailed model in the second file back into the master
Posting this in case other civil users have seen similar behaviour or have refinements to this workflow. Apologies in advance if this is a known issue, I had read back over recent threads and could not see a relevant discussion.
Comments
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Thank you for sharing, it can be useful indeed.
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