# We have a problem with IfcMapConversion

**URL:** <https://forums.buildingsmart.org/t/we-have-a-problem-with-ifcmapconversion/5695>\
**Category:** Users\
**Created:** [October 23, 2024, 9:29pm UTC](https://forums.buildingsmart.org/t/we-have-a-problem-with-ifcmapconversion/5695 "2024-10-23T21:29:14Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![NickMein](https://avatars.discourse-cdn.com/v4/letter/n/7ba0ec/32.png) [@NickMein](https://forums.buildingsmart.org/u/NickMein)\
**Post date:** [October 23, 2024, 9:29pm UTC](https://forums.buildingsmart.org/t/we-have-a-problem-with-ifcmapconversion/5695/1 "2024-10-23T21:29:14Z")

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Hi all, we (the BIM industry) have a problem with IfcMapConversion. Or actually two problems:

1. We’ve seen two examples recently of software that is writing IfcMapConversion incorrectly. Specifically, in both cases, projected map coordinates were used as model coordinates (which is valid), but an IfcMapConversion was also included, which makes the final coordinates wildly wrong.
2. Very little software actually reads IfcMapConversion. Software that ignores the IfcMapConversion appears to give correct results when it reads one of these badly formed files, software that correctly applies the IfcMapConversion appears to give an incorrect result.

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**Author:** ![lee.gregory](https://avatars.discourse-cdn.com/v4/letter/l/eb9ed0/32.png) [@lee.gregory](https://forums.buildingsmart.org/u/lee.gregory)\
**Post date:** [October 29, 2024, 12:59am UTC](https://forums.buildingsmart.org/t/we-have-a-problem-with-ifcmapconversion/5695/2 "2024-10-29T00:59:34Z")

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**IfcMapConversion** is not that useful unless the combined scale factor is 1.0  
**IfcMapConversionScaled** in **IFC 4x3** is the correct one to us.

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**Author:** ![Moult](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.buildingsmart.org/moult/32/196_2.png) [@Moult](https://forums.buildingsmart.org/u/Moult)\
**Post date:** [November 1, 2024, 2:31am UTC](https://forums.buildingsmart.org/t/we-have-a-problem-with-ifcmapconversion/5695/3 "2024-11-01T02:31:45Z")

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Please report the bugs to any software vendor that 1) writes it incorrectly or 2) does not read it correctly or ignores it. They might not be aware of the issue.