# Latest

**URL:** https://discourse.radiance-online.org/latest.md?page=1

[Latest](https://discourse.radiance-online.org/latest.md) · [Categories](https://discourse.radiance-online.org/categories.md)

**Page:** 2

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## [Rendering with Radiance errata and updates](https://discourse.radiance-online.org/t/rendering-with-radiance-errata-and-updates/6953)

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**Author:** [@Dion\_Moult](https://discourse.radiance-online.org/u/Dion_Moult)\
**Replies:** 1\
**Last updated:** [January 13, 2026, 9:17pm UTC](https://discourse.radiance-online.org/t/rendering-with-radiance-errata-and-updates/6953 "2026-01-13T21:17:19Z")

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I’ve been re-reading Rendering with Radiance and it is incredible how it is still perhaps the most beginner friendly, comprehensive introduction to Radiance. The edition I have is from 2011. Is there an update? I have no…

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## [2026 Radiance Workshop in Seattle, WA](https://discourse.radiance-online.org/t/2026-radiance-workshop-in-seattle-wa/6952)

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**Author:** [@Greg\_Ward](https://discourse.radiance-online.org/u/Greg_Ward)\
**Replies:** 0\
**Last updated:** [January 11, 2026, 6:14pm UTC](https://discourse.radiance-online.org/t/2026-radiance-workshop-in-seattle-wa/6952 "2026-01-11T18:14:54Z")

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Professor Mehlika Inanici of the University of Washington has volunteered to host this year’s Radiance workshop, which will be held in Seattle. The likely dates will be from August 31st through September 2nd, 2026. Ple…

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## [Simulation time for artificial lighting](https://discourse.radiance-online.org/t/simulation-time-for-artificial-lighting/6948)

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**Author:** [@Ery\_Djunaedy1](https://discourse.radiance-online.org/u/Ery_Djunaedy1)\
**Replies:** 2\
**Last updated:** [January 8, 2026, 4:22am UTC](https://discourse.radiance-online.org/t/simulation-time-for-artificial-lighting/6948 "2026-01-08T04:22:30Z")

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All, I have a problem. In a nutshell: I have a simulation that has been running for five days, and that is not even half-way through. The previous version runs for about 24 hours to complete. The only difference between …

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## [Postdoctoral fellowships at the Department of Architecture at ETH Zurich](https://discourse.radiance-online.org/t/postdoctoral-fellowships-at-the-department-of-architecture-at-eth-zurich/6950)

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**Author:** [@Lars\_Grobe](https://discourse.radiance-online.org/u/Lars_Grobe)\
**Replies:** 0\
**Last updated:** [January 7, 2026, 3:45pm UTC](https://discourse.radiance-online.org/t/postdoctoral-fellowships-at-the-department-of-architecture-at-eth-zurich/6950 "2026-01-07T15:45:44Z")

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Dear all, the Daylight Integration Nexus DINx at ETHZ calls for applications / research proposals: Integrative research in occupant-centric daylighting (open now until end of February) Integrative research in the art …

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## [Irradiance from illuminance for scene with IES - Compared to real-world measurements](https://discourse.radiance-online.org/t/irradiance-from-illuminance-for-scene-with-ies-compared-to-real-world-measurements/6933)

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**Author:** [@RafaelBartsch](https://discourse.radiance-online.org/u/RafaelBartsch)\
**Replies:** 3\
**Last updated:** [January 3, 2026, 10:13pm UTC](https://discourse.radiance-online.org/t/irradiance-from-illuminance-for-scene-with-ies-compared-to-real-world-measurements/6933 "2026-01-03T22:13:55Z")

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Hello everyone I’m new to the forum, but have been a reading member for a long time, I’m currently trying to derive irradiance from illuminance values for a scene, lit by an IES light source. I do have the SPD and the …

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## [Using -av to approximate higher-order reflections](https://discourse.radiance-online.org/t/using-av-to-approximate-higher-order-reflections/6941)

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**Author:** [@Funerus](https://discourse.radiance-online.org/u/Funerus)\
**Replies:** 2\
**Last updated:** [December 27, 2025, 11:16am UTC](https://discourse.radiance-online.org/t/using-av-to-approximate-higher-order-reflections/6941 "2025-12-27T11:16:44Z")

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Hello, I want to determine an appropriate ambient value (-av) to approximate higher-order reflections in a geometrically complex scene. The scene consists of a tree with multiple overlapping leaves, and I sample irradi…

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## [Rpict: warning - no output produced"](https://discourse.radiance-online.org/t/rpict-warning-no-output-produced/6938)

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**Author:** [@Kera\_Lagios1](https://discourse.radiance-online.org/u/Kera_Lagios1)\
**Replies:** 8\
**Last updated:** [December 23, 2025, 10:41pm UTC](https://discourse.radiance-online.org/t/rpict-warning-no-output-produced/6938 "2025-12-23T22:41:20Z")

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Hi Everyone, I’m having trouble with BSDFs. I assume it’s something obvious. Ultimately the goal is to get a perforated, opaque material, screen (1/4” thick) to show up in renderings. I have been referencing Andy’s genB…

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## [“Trouble finding HDR patches”](https://discourse.radiance-online.org/t/trouble-finding-hdr-patches/6942)

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**Author:** [@bing](https://discourse.radiance-online.org/u/bing)\
**Replies:** 9\
**Last updated:** [December 19, 2025, 5:38pm UTC](https://discourse.radiance-online.org/t/trouble-finding-hdr-patches/6942 "2025-12-19T17:38:15Z")

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Hi everyone, I’m a student currently working on merging LDR images and I’ve run into an issue that I hope someone can help me with. When I use hdrgen on a Linux system to execute the command for combining and generatin…

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## [WSL2: rvu, ximage now run beatifully on Win11](https://discourse.radiance-online.org/t/wsl2-rvu-ximage-now-run-beatifully-on-win11/6943)

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**Author:** [@Axel\_Jacobs2](https://discourse.radiance-online.org/u/Axel_Jacobs2)\
**Replies:** 0\
**Last updated:** [December 18, 2025, 8:01pm UTC](https://discourse.radiance-online.org/t/wsl2-rvu-ximage-now-run-beatifully-on-win11/6943 "2025-12-18T20:01:03Z")

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Hey guys, We got our shiny new Win11 laptops a few months ago, and I had another go at getting rvu and ximage running on WSL2. I did attempt to do this on our old Win10 laptops, but never managed to get Radiance’s X11 …

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## [unit of irradiance using epw as input](https://discourse.radiance-online.org/t/unit-of-irradiance-using-epw-as-input/4416)

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**Author:** [@David\_Davidson](https://discourse.radiance-online.org/u/David_Davidson)\
**Replies:** 9\
**Last updated:** [December 8, 2025, 7:43pm UTC](https://discourse.radiance-online.org/t/unit-of-irradiance-using-epw-as-input/4416 "2025-12-08T19:43:25Z")

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Hi, may I ask if the unit of irradiance is \*Wh/m2\* if I use the "epw weather file + gendaylit/gencumulativesky + rtrace" method to get the irradiance of a given point for a particular hour in a year or annual total ir…

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## [How to visualize a sky vector?](https://discourse.radiance-online.org/t/how-to-visualize-a-sky-vector/1198)

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**Author:** [@Wouter\_Beck\_Ascendil](https://discourse.radiance-online.org/u/Wouter_Beck_Ascendil)\
**Replies:** 9\
**Last updated:** [December 9, 2025, 2:51pm UTC](https://discourse.radiance-online.org/t/how-to-visualize-a-sky-vector/1198 "2025-12-09T14:51:31Z")

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In several places I see nice false color luminance representations of Perez skies. Trying to render or preferably plot such a representation from a sky vector appears not to be so easy. I looked at Andy's McNeil\_BS…

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## [Electric light calculation by using IES files with Accelerad](https://discourse.radiance-online.org/t/electric-light-calculation-by-using-ies-files-with-accelerad/6931)

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**Author:** [@Majid\_Miri](https://discourse.radiance-online.org/u/Majid_Miri)\
**Replies:** 3\
**Last updated:** [December 2, 2025, 12:30am UTC](https://discourse.radiance-online.org/t/electric-light-calculation-by-using-ies-files-with-accelerad/6931 "2025-12-02T00:30:17Z")

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Hi all, I’m wondering whether it’s possible to perform electric lighting calculations on the GPU (similar to using Accelerad) by importing IES files. In other words, does anyone know how to use Accelerad to run lighting…

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## [Radiance Workshop 2025, EPFL Lausanne](https://discourse.radiance-online.org/t/radiance-workshop-2025-epfl-lausanne/6806)

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**Author:** [@Jan\_Wienold](https://discourse.radiance-online.org/u/Jan_Wienold)\
**Replies:** 13\
**Last updated:** [November 12, 2025, 4:50pm UTC](https://discourse.radiance-online.org/t/radiance-workshop-2025-epfl-lausanne/6806 "2025-11-12T16:50:25Z")

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Hi Everyone! Great news—we didn’t receive any objections to the proposed workshop 2025 dates, so we’ve now finalized them: August 27-29! We’re excited to announce that the LIPID lab at EPFL will be hosting this year’s w…

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## [New/updated annual simulation tools](https://discourse.radiance-online.org/t/new-updated-annual-simulation-tools/6918)

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**Author:** [@Greg\_Ward](https://discourse.radiance-online.org/u/Greg_Ward)\
**Replies:** 0\
**Last updated:** [October 29, 2025, 9:39pm UTC](https://discourse.radiance-online.org/t/new-updated-annual-simulation-tools/6918 "2025-10-29T21:39:21Z")

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Dear Users, We just introduced a new tool with nearly identical semantics to rfluxmtx, but based on the Radiance C++ library interface. It is called rxfluxmtx, following suit from rxpiece, which was introduced to the U…

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## [Simulating a LED Strip Light using an IES File](https://discourse.radiance-online.org/t/simulating-a-led-strip-light-using-an-ies-file/6912)

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**Author:** [@jmmonteoliva](https://discourse.radiance-online.org/u/jmmonteoliva)\
**Replies:** 4\
**Last updated:** [October 28, 2025, 6:38pm UTC](https://discourse.radiance-online.org/t/simulating-a-led-strip-light-using-an-ies-file/6912 "2025-10-28T18:38:34Z")

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Hello Radiance community, I’m trying to reproduce a luminaire similar to a LED strip light. I’ve attached a reference (link) because I’m not sure if “LED strike light” is the correct term. The idea is to simulate, on on…

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## [Evalglare calculation on edge of image](https://discourse.radiance-online.org/t/evalglare-calculation-on-edge-of-image/6895)

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**Author:** [@bzxgcs](https://discourse.radiance-online.org/u/bzxgcs)\
**Replies:** 5\
**Last updated:** [October 2, 2025, 11:14am UTC](https://discourse.radiance-online.org/t/evalglare-calculation-on-edge-of-image/6895 "2025-10-02T11:14:34Z")

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Hi Radiance Community, I am trying to use evalglare to calculate glare values. I used the -G option to crop the field of view to the correct range. However, I noticed that the overhead light (located at the edge of the …

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## [Unsupported image format with raw2hdr](https://discourse.radiance-online.org/t/unsupported-image-format-with-raw2hdr/6857)

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**Author:** [@altamar](https://discourse.radiance-online.org/u/altamar)\
**Replies:** 11\
**Last updated:** [September 17, 2025, 2:40am UTC](https://discourse.radiance-online.org/t/unsupported-image-format-with-raw2hdr/6857 "2025-09-17T02:40:06Z")

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Hello Radiance community, I’m trying to reproduce an HDR workflow I originally set up in 2020 on Ubuntu, using raw2hdr to process Canon 6D Mark II .CR2 files. Back then the same script ran without issues, but today I ge…

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## [Glazing Material (for glare)](https://discourse.radiance-online.org/t/glazing-material-for-glare/6885)

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**Author:** [@homan95](https://discourse.radiance-online.org/u/homan95)\
**Replies:** 5\
**Last updated:** [September 13, 2025, 3:47am UTC](https://discourse.radiance-online.org/t/glazing-material-for-glare/6885 "2025-09-13T03:47:31Z")

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Hi all, I am trying to assess glare from a neighbouring building’s glazing. What would be an appropriate material to be used for the glazing? I have read that dielectric or trans may be applicable (with trans being hard…

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## [Rtrace (-co+) output unit](https://discourse.radiance-online.org/t/rtrace-co-output-unit/6882)

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**Author:** [@NimaForouzandeh](https://discourse.radiance-online.org/u/NimaForouzandeh)\
**Replies:** 2\
**Last updated:** [August 27, 2025, 7:25am UTC](https://discourse.radiance-online.org/t/rtrace-co-output-unit/6882 "2025-08-27T07:25:05Z")

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Dear Radiance community, I am comparing a measured irradiance read with a simulated one from Radiance v6.0. The shape of the output is very close, but I am confused about the unit. Under an overcast sky, the irradiance…

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## [Raw2hdr with CR2 files from Canon](https://discourse.radiance-online.org/t/raw2hdr-with-cr2-files-from-canon/6881)

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**Author:** [@altamar](https://discourse.radiance-online.org/u/altamar)\
**Replies:** 1\
**Last updated:** [August 23, 2025, 3:31am UTC](https://discourse.radiance-online.org/t/raw2hdr-with-cr2-files-from-canon/6881 "2025-08-23T03:31:34Z")

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I have a canon 5D and i am shooting in raw, as you probably familiar, canon uses proprietary CR2. I have been trying with no success to generate an hdr image until now. With the help of chatgpt, we debugged the raw2hdr…

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## [Radiance workshop in Lausanne - update](https://discourse.radiance-online.org/t/radiance-workshop-in-lausanne-update/6880)

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**Author:** [@Jan\_Wienold](https://discourse.radiance-online.org/u/Jan_Wienold)\
**Replies:** 0\
**Last updated:** [August 21, 2025, 7:58am UTC](https://discourse.radiance-online.org/t/radiance-workshop-in-lausanne-update/6880 "2025-08-21T07:58:18Z")

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Hello everyone, I’m excited to share that we were able to put together a very interesting program for the upcoming Radiance and HDR workshops (see the overview below). If you haven’t registered yet, now is the perfect …

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## [Seeking Advice on Vignetting Correction](https://discourse.radiance-online.org/t/seeking-advice-on-vignetting-correction/6878)

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**Author:** [@Joe\_Chow](https://discourse.radiance-online.org/u/Joe_Chow)\
**Replies:** 0\
**Last updated:** [August 19, 2025, 2:40pm UTC](https://discourse.radiance-online.org/t/seeking-advice-on-vignetting-correction/6878 "2025-08-19T14:40:49Z")

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Hello everyone, I understand that vignetting correction is important. However, I am not familiar with the vignetting function and do not have the necessary instruments to determine it. Currently, I am using a Nikon Z5 t…

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## [The selection of camera & lens](https://discourse.radiance-online.org/t/the-selection-of-camera-lens/6870)

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**Author:** [@Joe\_Chow](https://discourse.radiance-online.org/u/Joe_Chow)\
**Replies:** 5\
**Last updated:** [August 14, 2025, 12:13pm UTC](https://discourse.radiance-online.org/t/the-selection-of-camera-lens/6870 "2025-08-14T12:13:39Z")

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Dear All, I am writing to enquiry whether the instruments that I selected are apporiate to record the LDR and HDR images. Camera: ESO R8 Lens: Sigma 8mm F3.5 I have attached the specifications of these instruments. L…

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## [Comparison of \`gendaylit\` multi-channel sky with \`genssky\`](https://discourse.radiance-online.org/t/comparison-of-gendaylit-multi-channel-sky-with-genssky/6867)

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**Author:** [@NimaForouzandeh](https://discourse.radiance-online.org/u/NimaForouzandeh)\
**Replies:** 3\
**Last updated:** [August 1, 2025, 3:44pm UTC](https://discourse.radiance-online.org/t/comparison-of-gendaylit-multi-channel-sky-with-genssky/6867 "2025-08-01T15:44:16Z")

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Dear all, I need to compare the 9-channel spectral sky that Lark uses and a spectral 18-channel sky from Radiance v6.0. I need help understanding how I can compare these two skies. How can the sky and sun in Radiance v…

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## [Converting multi channel value to a Radiance value with Radiance command](https://discourse.radiance-online.org/t/converting-multi-channel-value-to-a-radiance-value-with-radiance-command/6874)

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**Author:** [@Majid\_Miri](https://discourse.radiance-online.org/u/Majid_Miri)\
**Replies:** 4\
**Last updated:** [July 31, 2025, 6:16am UTC](https://discourse.radiance-online.org/t/converting-multi-channel-value-to-a-radiance-value-with-radiance-command/6874 "2025-07-31T06:16:48Z")

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In Radiance, we can use the following formula to convert 3-channel data (Red, Green, and Blue) into a single Radiance value: Radiance = 0.265 × Red + 0.670 × Green + 0.065 × Blue My question is: how can we extend this …

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## [Official Radiance 6.0 release](https://discourse.radiance-online.org/t/official-radiance-6-0-release/6873)

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**Author:** [@Greg\_Ward](https://discourse.radiance-online.org/u/Greg_Ward)\
**Replies:** 0\
**Last updated:** [July 24, 2025, 6:48pm UTC](https://discourse.radiance-online.org/t/official-radiance-6-0-release/6873 "2025-07-24T18:48:42Z")

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We have an official set of 6.0 installers now uploaded at: We haven’t made an official release in a while, let alone a major one. Here are some of the significant additions from src/notes/ReleaseNotes: =============…

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## [IFC file conversion to Obj](https://discourse.radiance-online.org/t/ifc-file-conversion-to-obj/6869)

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**Author:** [@Vin](https://discourse.radiance-online.org/u/Vin)\
**Replies:** 4\
**Last updated:** [July 17, 2025, 4:04pm UTC](https://discourse.radiance-online.org/t/ifc-file-conversion-to-obj/6869 "2025-07-17T16:04:56Z")

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Hi All, Has anyone successfully converted IFC file to OBJ file with a valid .mtl file for rendering a floor plan of a building. Its been difficult to find a converter that successfully does this. The IFC files I’m work…

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## [Extracting sunlit areas from an rpict .HDR file](https://discourse.radiance-online.org/t/extracting-sunlit-areas-from-an-rpict-hdr-file/6868)

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**Author:** [@Vin](https://discourse.radiance-online.org/u/Vin)\
**Replies:** 1\
**Last updated:** [July 17, 2025, 2:45am UTC](https://discourse.radiance-online.org/t/extracting-sunlit-areas-from-an-rpict-hdr-file/6868 "2025-07-17T02:45:54Z")

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Hi there, Apologies if this question may have been covered elsewhere. I am attempting to extract the sunlit areas from a .hdr file output from rpict. The goal is to extract the sunlit pixels in order to combine a sequ…

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## [rad and/or mgf to 3ds/dxf](https://discourse.radiance-online.org/t/rad-and-or-mgf-to-3ds-dxf/3974)

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**Author:** [@Dr\_Cristiano\_Guarnas](https://discourse.radiance-online.org/u/Dr_Cristiano_Guarnas)\
**Replies:** 11\
**Last updated:** [June 28, 2025, 9:26am UTC](https://discourse.radiance-online.org/t/rad-and-or-mgf-to-3ds-dxf/3974 "2025-06-28T09:26:50Z")

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Hello to everyone I never wrote in here before cause all my questiond found an answer in the archives but not this time. I lost a source 3d file of an old project, I have only in radiance format (and then mgf format…

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## [Measuring GHI with rtrace in scenes with diffuse irradiance](https://discourse.radiance-online.org/t/measuring-ghi-with-rtrace-in-scenes-with-diffuse-irradiance/6842)

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**Author:** [@felix.perez](https://discourse.radiance-online.org/u/felix.perez)\
**Replies:** 6\
**Last updated:** [June 9, 2025, 1:42pm UTC](https://discourse.radiance-online.org/t/measuring-ghi-with-rtrace-in-scenes-with-diffuse-irradiance/6842 "2025-06-09T13:42:51Z")

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Hi all, I have a question regarding the results of rtrace when measuring irradiance. When looking at the results of rtrace, we noticed that we were “missing” some irradiance, in the sense that we were not getting the ex…

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