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IDProjectCategoryView StatusLast Update
0033907CommunityOCCT:Modeling Datapublic2026-01-15 14:24
Reporterj.bourgoin Assigned Toj.bourgoin  
PrioritynormalSeverityminor 
Status feedbackResolutionopen 
PlatformWindowsOSVC++ 2022 
Product Version7.7.1 
Summary0033907: Computed volume is not the same as the one given by CADAssistant
DescriptionHello,

With the attached brep, I get a volume of 329.6, but with CADAssistant I get a volume of 334.6.

Why is there a difference please ?
Steps To Reproduce    TopoDS_Shape lShape ;
    BRep_Builder lBuilder ;
    GProp_GProps lProperties ;
    BRepTools::Read(lShape, "shape.brep", lBuilder) ;
    BRepGProp::VolumeProperties(lShape, lProperties) ;
    double lVolume = lProperties.Mass() ;
TagsNo tags attached.
Test case number

Attached Files

Activities

j.bourgoin

2025-09-11 17:55

reporter   ~0117085

Input BRep
shape.brep (710,775 bytes)   

ika

2025-10-01 16:30

reporter   ~0117090

Last edited: 2026-01-15 14:24

There are two approaches of volume computation, using algorithms on BRep and on Mesh. Obviously, the second one depends on mesh quality and results can differ. CADAsssitant uses only the Mesh algorithm, while OCCT can use both, and by default uses BRep.
If you want to receive the similar results you can repeat your experiment with the mesh-only model. If you will use BRep+Mesh, CADAssistant will remesh it for Volume properties calculation with its internal parameters, so the experiment will fail.
To use algorithm on triangulation in OCCT the model should have triangulation and UseTriangulation = true parameter should be used in a method call.

Issue History

Date Modified Username Field Change
2025-09-11 17:55 j.bourgoin New Issue
2025-09-11 17:55 j.bourgoin Assigned To => akaftasev
2025-09-11 17:55 j.bourgoin Note Added: 0117085
2025-09-11 17:55 j.bourgoin File Added: shape.brep
2025-10-01 16:30 ika Note Added: 0117090
2025-10-01 16:30 ika File Added: plane.jpg
2026-01-07 14:26 dpasukhi Note View State: 0117090: public
2026-01-07 15:05 dpasukhi Assigned To akaftasev => j.bourgoin
2026-01-07 15:05 dpasukhi Status new => feedback
2026-01-15 14:24 ika Note Edited: 0117090
2026-01-15 14:24 ika File Deleted: plane.jpg