You signed in with another tab or window. Reload to refresh your session.You signed out in another tab or window. Reload to refresh your session.You switched accounts on another tab or window. Reload to refresh your session.Dismiss alert
#19=IFCSIUNIT(*,.LENGTHUNIT.,.MILLI.,.METRE.);
#97=IFCUNITASSIGNMENT((#19,#21,#22,#26,#27,#30,#31,#33,#34,#35,#37,#40,#42,#46,#47,#48,#49,#50,#51,#52,#53,#54,#55,#56,#61,#64,#66,#69,#70,#71,#72,#73,#74,#75,#76,#77,#79,#80,#81,#82,#83,#84,#85,#86,#88,#89,#91,#92,#94,#95,#96));
...
#105=IFCSIUNIT(*,.LENGTHUNIT.,$,.METRE.);
#106=IFCPROJECTEDCRS('EPSG:7856','Map Grid of Australia Zone 56, GDA2020 (7Parameter)','GDA2020-7P',$,$,$,#105);
#107=IFCMAPCONVERSION(#100,#106,20.000000000000004,10.000000000000002,0.,1.,6.1230317691118863E-17,$);
...
As you can see:
Project units are in mm (good)
Projected CRS defined (good)
Projected CRS has a map unit of meters (sure)
Map conversion has an easting and northings of 20 and 10 (in meters, good :) it matches the map unit which is great!)
Map conversion has a null value for Scale (bug)
IFC states:
The scale factor can be used when the length unit for the 3 axes of the map coordinate system are not identical with the length unit established for this project (see IfcProject.UnitsInContext), if omitted, the scale factor 1.0 is assumed.
and repeats itself
Scale to be used, when the units of the CRS are not identical to the units of the engineering coordinate system. If omited, the value of 1.0 is assumed.
Because it is omitted, the value of 1.0 is assumed. But the units of the CRS (m) are not identical to the project units (mm). So this is not correct - there needs to be a value for scale.
According to this equation as you can see first we scale the project units XYZ then we add the eastings/northings. So the scale should be equal to 0.001 (to go from mm -> m, then we can add the eastings/northings in m).
(ignore the FactorXYZ that is for IfcMapConversionScaled but the general equation still applies)
Revit Version
2023.1.x
IFC for Revit Addon Version
24.x.x
Windows Version
11 22H2
The text was updated successfully, but these errors were encountered:
Problem Description
Here is a blank project in metric millimeters as the project unit. The coordinates at the PBP is 10,000mm and 20,000mm.
The projected CRS is EPSG:7856.
Revit will export this data in IFC:
Project2 - Copy.txt
As you can see:
IFC states:
and repeats itself
on the docs for IfcMapConversion
Because it is omitted, the value of 1.0 is assumed. But the units of the CRS (m) are not identical to the project units (mm). So this is not correct - there needs to be a value for scale.
According to this equation as you can see first we scale the project units XYZ then we add the eastings/northings. So the scale should be equal to
0.001
(to go from mm -> m, then we can add the eastings/northings in m).(ignore the FactorXYZ that is for IfcMapConversionScaled but the general equation still applies)
Revit Version
2023.1.x
IFC for Revit Addon Version
24.x.x
Windows Version
11 22H2
The text was updated successfully, but these errors were encountered: