# Developers **URL:** https://forums.buildingsmart.org/c/developers/28.md?page=3 [Latest](https://forums.buildingsmart.org/latest.md) · [Categories](https://forums.buildingsmart.org/categories.md) · [Tags](https://forums.buildingsmart.org/tags.md) **Page:** 4 --- ## [Add Unit (IfcUnit) to IfcPropertySingleValue](https://forums.buildingsmart.org/t/add-unit-ifcunit-to-ifcpropertysinglevalue/4747)
**Author:** [@steinerb](https://forums.buildingsmart.org/u/steinerb)\ **Replies:** 2\ **Last updated:** [May 31, 2023, 11:53pm UTC](https://forums.buildingsmart.org/t/add-unit-ifcunit-to-ifcpropertysinglevalue/4747 "2023-05-31T23:53:09Z")
A python script produces an IFC-file wherein the following line appears several times: PropertySingleValueWriter = ifcfile.createIfcPropertySingleValue("{}".format(V), "{}".format(k), ifcfile.create\_entity("IfcText", st… --- ## [IfcPolynomialCurve clarification](https://forums.buildingsmart.org/t/ifcpolynomialcurve-clarification/4716)
**Author:** [@andriib](https://forums.buildingsmart.org/u/andriib)\ **Replies:** 1\ **Last updated:** [May 19, 2023, 3:38am UTC](https://forums.buildingsmart.org/t/ifcpolynomialcurve-clarification/4716 "2023-05-19T03:38:10Z")
Hello Experts, I am investigating new entities that were introduced in IFC4x3. And I have noticed that the IfcPolynomialCurve specification is not fully completed yet. So, the description of this entity in terms of IF… --- ## [Element Area Hierarchy](https://forums.buildingsmart.org/t/element-area-hierarchy/3034)
**Author:** [@glennnz](https://forums.buildingsmart.org/u/glennnz)\ **Replies:** 3\ **Last updated:** [May 4, 2023, 2:33am UTC](https://forums.buildingsmart.org/t/element-area-hierarchy/3034 "2023-05-04T02:33:15Z")
Hi, Can anyone point me to the hierarchical structure of how to drill down to an element’s surface area? I am trying to use either a .ifc or .ifcxml file from ArchiCAD to extract element areas. Thanks, Glenn --- ## [Pset\_Uncertainty usage](https://forums.buildingsmart.org/t/pset-uncertainty-usage/4707)
**Author:** [@jwouellette](https://forums.buildingsmart.org/u/jwouellette)\ **Replies:** 2\ **Last updated:** [April 13, 2023, 7:54pm UTC](https://forums.buildingsmart.org/t/pset-uncertainty-usage/4707 "2023-04-13T19:54:40Z")
Can someone give me an example of how Pset\_Uncertainty would be used? https://ifc43-docs.standards.buildingsmart.org/IFC/RELEASE/IFC4x3/HTML/lexical/Pset\_Uncertainty.htm --- ## [STEP Exponential Number format](https://forums.buildingsmart.org/t/step-exponential-number-format/4688)
**Author:** [@jonm](https://forums.buildingsmart.org/u/jonm)\ **Replies:** 9\ **Last updated:** [April 5, 2023, 4:50pm UTC](https://forums.buildingsmart.org/t/step-exponential-number-format/4688 "2023-04-05T16:50:47Z")
Does STEP serialization support numbers formated to an exponential format (eg -1E-04 )? I see several toolkits writing this, but when validating on the buildingSMART website an error is suggested when this is used. ie … --- ## [IfcRelDefinesByObject - anyone using?](https://forums.buildingsmart.org/t/ifcreldefinesbyobject-anyone-using/4527)
**Author:** [@Theoryshaw](https://forums.buildingsmart.org/u/Theoryshaw)\ **Replies:** 3\ **Last updated:** [April 5, 2023, 12:13am UTC](https://forums.buildingsmart.org/t/ifcreldefinesbyobject-anyone-using/4527 "2023-04-05T00:13:49Z")
Does anyone know if there’s any applications, currently, that use IfcRelDefinesByObject? Here’s only one example, out in the wild, that includes it. --- ## [Orientation of cross sections in IfcSectionedSolidHorizontal defined by IfcAxis2PlacementLinear](https://forums.buildingsmart.org/t/orientation-of-cross-sections-in-ifcsectionedsolidhorizontal-defined-by-ifcaxis2placementlinear/4696)
**Author:** [@kalep](https://forums.buildingsmart.org/u/kalep)\ **Replies:** 0\ **Last updated:** [April 3, 2023, 9:19am UTC](https://forums.buildingsmart.org/t/orientation-of-cross-sections-in-ifcsectionedsolidhorizontal-defined-by-ifcaxis2placementlinear/4696 "2023-04-03T09:19:12Z")
I’m trying to understand the orientation of cross sections in IfcSectionedSolidHorizontal defined by IfcAxis2PlacementLinear, as specified in IFC4x3 (final). There are two statements: 1. The profile normal is derived… --- ## [Analysis of propertySets in bSDD](https://forums.buildingsmart.org/t/analysis-of-propertysets-in-bsdd/4671)
**Author:** [@VladimirAlexiev](https://forums.buildingsmart.org/u/VladimirAlexiev)\ **Replies:** 1\ **Last updated:** [March 23, 2023, 1:15pm UTC](https://forums.buildingsmart.org/t/analysis-of-propertysets-in-bsdd/4671 "2023-03-23T13:15:32Z")
Related to Bsdd access for products and classification standard / bsdd guid vs ifc guid - #23 by VladimirAlexiev, I made some SPARQL queries to analyze propSets in the bSDD test instance. You should be able to run them … --- ## [Pset/QTo: Missing information in xml in version 4x3 (no guid and aliases anymore)](https://forums.buildingsmart.org/t/pset-qto-missing-information-in-xml-in-version-4x3-no-guid-and-aliases-anymore/4659)
**Author:** [@schilu](https://forums.buildingsmart.org/u/schilu)\ **Replies:** 1\ **Last updated:** [March 17, 2023, 3:58pm UTC](https://forums.buildingsmart.org/t/pset-qto-missing-information-in-xml-in-version-4x3-no-guid-and-aliases-anymore/4659 "2023-03-17T15:58:13Z")
I recognised that the pset and qto definitions have changed in version 4x3 (IFC4X3\_TC1 and IFC4X3\_ADD1). In the corresponding xml files with the pset/qto-definitions there are no IfdGuids and no Aliases (name and definit… --- ## [Why is there no IfcProjectionElementType?](https://forums.buildingsmart.org/t/why-is-there-no-ifcprojectionelementtype/4637)
**Author:** [@angel.velez](https://forums.buildingsmart.org/u/angel.velez)\ **Replies:** 6\ **Last updated:** [March 2, 2023, 11:35pm UTC](https://forums.buildingsmart.org/t/why-is-there-no-ifcprojectionelementtype/4637 "2023-03-02T23:35:13Z")
It seems like without a type, it is a sub-optimal entity type to use for mapping objects that have both instance and type properties. --- ## [IfcDistributionPort related to IfcTypeObject](https://forums.buildingsmart.org/t/ifcdistributionport-related-to-ifctypeobject/4617)
**Author:** [@toni.qin](https://forums.buildingsmart.org/u/toni.qin)\ **Replies:** 4\ **Last updated:** [February 16, 2023, 9:18pm UTC](https://forums.buildingsmart.org/t/ifcdistributionport-related-to-ifctypeobject/4617 "2023-02-16T21:18:15Z")
Hello there. I have a question about the placement of an IfcDistributionPort. In this case, the IfcDistributionPort (#292) is associated to a TypeObject, IfcAirTerminialType(#286). The IfcAirTerminialType(#286) is used… --- ## [Can opening element geometry have \_any\_ material associated with it?](https://forums.buildingsmart.org/t/can-opening-element-geometry-have-any-material-associated-with-it/4621)
**Author:** [@angel.velez](https://forums.buildingsmart.org/u/angel.velez)\ **Replies:** 3\ **Last updated:** [February 15, 2023, 1:34pm UTC](https://forums.buildingsmart.org/t/can-opening-element-geometry-have-any-material-associated-with-it/4621 "2023-02-15T13:34:09Z")
IfcOpeningElement is not allowed to have a material association. It can have representation items with materials/colors, though. Should we be respecting these materials/colors on import? --- ## [A number of interesting Revit IFC parsing errors.](https://forums.buildingsmart.org/t/a-number-of-interesting-revit-ifc-parsing-errors/4605)
**Author:** [@ian](https://forums.buildingsmart.org/u/ian)\ **Replies:** 12\ **Last updated:** [February 8, 2023, 9:03pm UTC](https://forums.buildingsmart.org/t/a-number-of-interesting-revit-ifc-parsing-errors/4605 "2023-02-08T21:03:20Z")
We have an IFC that is created by Revit. It is exhibiting some interesting parsing errors. It’s possible that our parser is being too strict, but this particular file also exhibits errors in ArchiCAD, but not in BlenderB… --- ## [List of changes between IFC versions?](https://forums.buildingsmart.org/t/list-of-changes-between-ifc-versions/4604)
**Author:** [@CarlosVasquez](https://forums.buildingsmart.org/u/CarlosVasquez)\ **Replies:** 3\ **Last updated:** [February 3, 2023, 7:31am UTC](https://forums.buildingsmart.org/t/list-of-changes-between-ifc-versions/4604 "2023-02-03T07:31:03Z")
Hello, Is there a list of all the changes that occurred between, for example, IFC2x3 and IFC4? Mostly interested in changes to entities/predefined types. For example, which entities have been renamed or deprecated, what… --- ## [Suggestion for IfcBuildingStorey](https://forums.buildingsmart.org/t/suggestion-for-ifcbuildingstorey/1488)
**Author:** [@agron](https://forums.buildingsmart.org/u/agron)\ **Replies:** 12\ **Last updated:** [January 26, 2023, 7:12pm UTC](https://forums.buildingsmart.org/t/suggestion-for-ifcbuildingstorey/1488 "2023-01-26T19:12:07Z")
Hi, There is a topic going on about the case on the definition of IfcBuildingStorey which you can read here. As a result of those discussions and the few (but growing) POLL results, I would like to suggest this enhance… --- ## [Qto\_\*BaseQuantities suggestion](https://forums.buildingsmart.org/t/qto-basequantities-suggestion/4536)
**Author:** [@agron](https://forums.buildingsmart.org/u/agron)\ **Replies:** 15\ **Last updated:** [January 26, 2023, 11:52am UTC](https://forums.buildingsmart.org/t/qto-basequantities-suggestion/4536 "2023-01-26T11:52:39Z")
Hi, I have been struggling with some QTO topics in my daily routines and would like to make an improvement suggestion. When defining deliverables in a BEP, I often stumble upon Quantities that are not standard definiti… --- ## [Revit to IFC, Wall is dislocated](https://forums.buildingsmart.org/t/revit-to-ifc-wall-is-dislocated/4575)
**Author:** [@andreasd](https://forums.buildingsmart.org/u/andreasd)\ **Replies:** 3\ **Last updated:** [January 16, 2023, 2:41pm UTC](https://forums.buildingsmart.org/t/revit-to-ifc-wall-is-dislocated/4575 "2023-01-16T14:41:49Z")
Hello, I export from Revit IFC4… i have a wall that is always dislocated, how to solve it? KR Andreas --- ## [General Assembly of Implementers - March 2022](https://forums.buildingsmart.org/t/general-assembly-of-implementers-march-2022/4530)
**Author:** [@danlittle](https://forums.buildingsmart.org/u/danlittle)\ **Replies:** 2\ **Last updated:** [January 3, 2023, 11:03am UTC](https://forums.buildingsmart.org/t/general-assembly-of-implementers-march-2022/4530 "2023-01-03T11:03:43Z")
The next meeting of the General Assembly of Implementers has been scheduled for Wednesday 8th and Thursday 9th March 2023. The meetings are being sponsored by Procore and will take place at their head offices in Carpint… --- ## [How does IFC work with existing classification systems such as Omniclass, Uniformat, etc?](https://forums.buildingsmart.org/t/how-does-ifc-work-with-existing-classification-systems-such-as-omniclass-uniformat-etc/804)
**Author:** [@Moult](https://forums.buildingsmart.org/u/Moult)\ **Replies:** 14\ **Last updated:** [November 17, 2022, 5:28pm UTC](https://forums.buildingsmart.org/t/how-does-ifc-work-with-existing-classification-systems-such-as-omniclass-uniformat-etc/804 "2022-11-17T17:28:16Z")
G’day all from down under. If I am modeling building assets to be used in an OpenBIM model, it would be logical for me to categorise them as the various IfcElements that they represent (e.g. my 3D door will be an IfcDoor… --- ## [Need help with Revit 2x3 ifc export, trying to figure out how the colors are assigned.](https://forums.buildingsmart.org/t/need-help-with-revit-2x3-ifc-export-trying-to-figure-out-how-the-colors-are-assigned/4461)
**Author:** [@BimBo](https://forums.buildingsmart.org/u/BimBo)\ **Replies:** 4\ **Last updated:** [November 7, 2022, 7:45am UTC](https://forums.buildingsmart.org/t/need-help-with-revit-2x3-ifc-export-trying-to-figure-out-how-the-colors-are-assigned/4461 "2022-11-07T07:45:57Z")
Hello, first post here. Im trying to make a script using ifcopenshell to try to remedy the fitting color problem (not the same color like the system they are connected to). I cannot figure out how the IfcStyledItem is … --- ## [U-shape semantic definition](https://forums.buildingsmart.org/t/u-shape-semantic-definition/4454)
**Author:** [@leif.granholm](https://forums.buildingsmart.org/u/leif.granholm)\ **Replies:** 3\ **Last updated:** [October 31, 2022, 11:40pm UTC](https://forums.buildingsmart.org/t/u-shape-semantic-definition/4454 "2022-10-31T23:40:55Z")
Hello We have found that the u-shape semantic definition is inadequate. You can only specify an inner edge radius for but in real life profiles the is also an outer edge radius or in practice that edge radius is bigger… --- ## [How to identify the orientation of façade elements in IFC?](https://forums.buildingsmart.org/t/how-to-identify-the-orientation-of-facade-elements-in-ifc/4452)
**Author:** [@pbourreau](https://forums.buildingsmart.org/u/pbourreau)\ **Replies:** 1\ **Last updated:** [October 31, 2022, 1:31pm UTC](https://forums.buildingsmart.org/t/how-to-identify-the-orientation-of-facade-elements-in-ifc/4452 "2022-10-31T13:31:43Z")
Hi everyone, I am trying to extract with a simple Python script the façade elements (I am focusing on Walls and Windows only) according to their orientation from an ifc2x3. I am struggling in finding information on how… --- ## [How can I represent "Survey Points" in a BIM viewer?](https://forums.buildingsmart.org/t/how-can-i-represent-survey-points-in-a-bim-viewer/4431)
**Author:** [@Giacomo](https://forums.buildingsmart.org/u/Giacomo)\ **Replies:** 7\ **Last updated:** [October 28, 2022, 8:11pm UTC](https://forums.buildingsmart.org/t/how-can-i-represent-survey-points-in-a-bim-viewer/4431 "2022-10-28T20:11:55Z")
Hello, I’ve just started working on ifc files, the first thing I need to do is represent points in 3D space, I’m using GeometryGym. What I would like to achieve is to display the points as shown in the documentation: … --- ## [Relation between doors to rooms](https://forums.buildingsmart.org/t/relation-between-doors-to-rooms/3961)
**Author:** [@MZibell](https://forums.buildingsmart.org/u/MZibell)\ **Replies:** 5\ **Last updated:** [October 28, 2022, 5:08pm UTC](https://forums.buildingsmart.org/t/relation-between-doors-to-rooms/3961 "2022-10-28T17:08:31Z")
Hi, in our CAFM projects, a frequently occurring requirement to the IFC models is that a door contained in a model provides information on which two rooms it establishes a connection between (e.g. for the locking system… --- ## [Pset\_SoundAttenuation - timeSeries makes no sense](https://forums.buildingsmart.org/t/pset-soundattenuation-timeseries-makes-no-sense/4450)
**Author:** [@CamChatHel](https://forums.buildingsmart.org/u/CamChatHel)\ **Replies:** 0\ **Last updated:** [October 24, 2022, 7:28am UTC](https://forums.buildingsmart.org/t/pset-soundattenuation-timeseries-makes-no-sense/4450 "2022-10-24T07:28:00Z")
Hello, I was thinking about Pset\_SoundAttenuation again. For SoundPressure we definitely need frequency dependent values. The definition is written as: " A time series of sound pressure values measured in decibels at a… --- ## [Multiple "body" representations for a single IfcProductRepresentation](https://forums.buildingsmart.org/t/multiple-body-representations-for-a-single-ifcproductrepresentation/4405)
**Author:** [@angel.velez](https://forums.buildingsmart.org/u/angel.velez)\ **Replies:** 10\ **Last updated:** [October 20, 2022, 11:51am UTC](https://forums.buildingsmart.org/t/multiple-body-representations-for-a-single-ifcproductrepresentation/4405 "2022-10-20T11:51:45Z")
Hello all, I have seen some files that have multiple IfcShapeRepresentations of type “Body”. It seems to me that this is ambiguous - should import have those are alternate body representations, or should they be combine… --- ## [IfcSpatialZone Project Survey](https://forums.buildingsmart.org/t/ifcspatialzone-project-survey/4174)
**Author:** [@daviddelven](https://forums.buildingsmart.org/u/daviddelven)\ **Replies:** 2\ **Last updated:** [October 19, 2022, 9:03pm UTC](https://forums.buildingsmart.org/t/ifcspatialzone-project-survey/4174 "2022-10-19T21:03:16Z")
In buildingSMART International Building Room, we are working on a project about the implementation of the IfcSpatialZone entity. The project target is to create a technical report that includes a list of the potential … --- ## [Link to the latest IFC4.3 release for bridges and roads developpements](https://forums.buildingsmart.org/t/link-to-the-latest-ifc4-3-release-for-bridges-and-roads-developpements/4410)
**Author:** [@JeanGUAL](https://forums.buildingsmart.org/u/JeanGUAL)\ **Replies:** 3\ **Last updated:** [October 17, 2022, 7:01am UTC](https://forums.buildingsmart.org/t/link-to-the-latest-ifc4-3-release-for-bridges-and-roads-developpements/4410 "2022-10-17T07:01:37Z")
Hello everybody, I am sorry this is a basic question. We are developing bridges and roads softwares tools . We have found several links to ifc 4.3 : RC 1/2/4 voting . They have many differencies about bridges (like … --- ## [ifcSQL is on github](https://forums.buildingsmart.org/t/ifcsql-is-on-github/3743)
**Author:** [@bsbock](https://forums.buildingsmart.org/u/bsbock)\ **Replies:** 7\ **Last updated:** [October 12, 2022, 2:48pm UTC](https://forums.buildingsmart.org/t/ifcsql-is-on-github/3743 "2022-10-12T14:48:48Z")
ifcSQL is able to manage multiple schemas and multiple models or building component libraries in a single database. Now it is open source on github: See IfcSharp/IfcSQL (github.com) These are the capabilities of ifcSQ… --- ## [GUID valid/invalid](https://forums.buildingsmart.org/t/guid-valid-invalid/3776)
**Author:** [@Michael](https://forums.buildingsmart.org/u/Michael)\ **Replies:** 4\ **Last updated:** [October 7, 2022, 3:26am UTC](https://forums.buildingsmart.org/t/guid-valid-invalid/3776 "2022-10-07T03:26:33Z")
Hi I am currently dealing with a file where the IfcGuid is not ok from my point of view. GUID #13 = k0el31CUlyR1pRyDyerMEG GUID #54 = kWlNI3mgHyK1QDiBnEISNJ 1-6(EDITED).ifc (12.2 KB) Are IfcGuid’s allowed to start w… [Previous page](https://forums.buildingsmart.org/c/developers/28.md?page=2) [Next page](https://forums.buildingsmart.org/c/developers/28.md?page=4)