# radiance-general

**URL:** https://discourse.radiance-online.org/c/radiance-general/9.md?page=3

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

**Page:** 4

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## [Evalglare and small linear glare shapes?](https://discourse.radiance-online.org/t/evalglare-and-small-linear-glare-shapes/6595)

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**Author:** [@m.martinez](https://discourse.radiance-online.org/u/m.martinez)\
**Replies:** 2\
**Last updated:** [June 20, 2024, 4:50pm UTC](https://discourse.radiance-online.org/t/evalglare-and-small-linear-glare-shapes/6595 "2024-06-20T16:50:35Z")

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Hi all, I’m struggling to get evalglare to tell me what I want it to (that’s the right mindset, isn’t it :D) I have a long linear specular reflection that’s very bright, ~70,000 cd/m2, and no matter what I do with -b an…

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## [Automatically determining the Multiplier factor in Falsecolour](https://discourse.radiance-online.org/t/automatically-determining-the-multiplier-factor-in-falsecolour/6591)

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**Author:** [@Vin](https://discourse.radiance-online.org/u/Vin)\
**Replies:** 1\
**Last updated:** [June 19, 2024, 5:43pm UTC](https://discourse.radiance-online.org/t/automatically-determining-the-multiplier-factor-in-falsecolour/6591 "2024-06-19T17:43:14Z")

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This is my old workflow: Take raw illuminance pic from IESVE software Postprocess this pic into a Daylight factor Falsecolour place compliance area over the top of each room on a plan. Currently I’m trying to recrea…

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## [View naming not working when rad command is used to render .rif file(Windows)](https://discourse.radiance-online.org/t/view-naming-not-working-when-rad-command-is-used-to-render-rif-file-windows/6587)

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**Author:** [@chiragsingh1711](https://discourse.radiance-online.org/u/chiragsingh1711)\
**Replies:** 3\
**Last updated:** [June 19, 2024, 3:35pm UTC](https://discourse.radiance-online.org/t/view-naming-not-working-when-rad-command-is-used-to-render-rif-file-windows/6587 "2024-06-19T15:35:52Z")

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How to produce the error? The problem I am facing is the when I give an identifier name to view variable in .rif file and when I use rad to render it. there’s no output. Files that I have: This is my scene.rif file: …

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## [Confusion about the functions of using rtrace's -af and -n together to accelerate?](https://discourse.radiance-online.org/t/confusion-about-the-functions-of-using-rtraces-af-and-n-together-to-accelerate/6584)

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**Author:** [@Hao](https://discourse.radiance-online.org/u/Hao)\
**Replies:** 16\
**Last updated:** [June 11, 2024, 1:35am UTC](https://discourse.radiance-online.org/t/confusion-about-the-functions-of-using-rtraces-af-and-n-together-to-accelerate/6584 "2024-06-11T01:35:41Z")

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Hi everyone, One of the ways I learned in the discourse to speed up the Radiance is to use the -af and -n options of the rtrace command. In the manpage, the -af option will set the ambient file. The main function of the…

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## [Installation Error](https://discourse.radiance-online.org/t/installation-error/6579)

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**Author:** [@soushiyant](https://discourse.radiance-online.org/u/soushiyant)\
**Replies:** 1\
**Last updated:** [May 23, 2024, 4:11pm UTC](https://discourse.radiance-online.org/t/installation-error/6579 "2024-05-23T16:11:16Z")

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Hello everyone, I am very sorry to ask a question of such a basic level in the forum. Despite my efforts, I couldn’t solve it on my own. Before installing the software, I installed these libraries: “tcsh csh ghostscrip…

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## [Why does the mirror material not consider the fresnel reflection?](https://discourse.radiance-online.org/t/why-does-the-mirror-material-not-consider-the-fresnel-reflection/6575)

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**Author:** [@1112](https://discourse.radiance-online.org/u/1112)\
**Replies:** 2\
**Last updated:** [May 23, 2024, 8:54am UTC](https://discourse.radiance-online.org/t/why-does-the-mirror-material-not-consider-the-fresnel-reflection/6575 "2024-05-23T08:54:26Z")

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According to the document “Behavior of Materials in Radiance,” it appears that the consideration of Fresnel reflection was omitted. This is evident from the constant reflectance, which does not vary with incident angle. …

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## [Lo-o-o-ng evalglare times](https://discourse.radiance-online.org/t/lo-o-o-ng-evalglare-times/1380)

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**Author:** [@Randolph\_Fritz4](https://discourse.radiance-online.org/u/Randolph_Fritz4)\
**Replies:** 7\
**Last updated:** [May 21, 2024, 1:03pm UTC](https://discourse.radiance-online.org/t/lo-o-o-ng-evalglare-times/1380 "2024-05-21T13:03:20Z")

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I'm running evalglare on some 1000x1000 5-phase method output files, and getting runtimes in the 15+ minute neighborhood. Is this plausible? Or is there something serious wrong here? ···-- Randolph M. Fritz || rmfrit…

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## [Transmission through water](https://discourse.radiance-online.org/t/transmission-through-water/6549)

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**Author:** [@jroberts](https://discourse.radiance-online.org/u/jroberts)\
**Replies:** 10\
**Last updated:** [May 16, 2024, 4:19pm UTC](https://discourse.radiance-online.org/t/transmission-through-water/6549 "2024-05-16T16:19:22Z")

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Hello Radiance community! I know this topic is a bit of a hot potato, but it seems like most discussions around water are about reflection off the water’s surface, whereas I am interested in transmission through water. …

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## [What kind of file formate is better for Radiance from the Revit?](https://discourse.radiance-online.org/t/what-kind-of-file-formate-is-better-for-radiance-from-the-revit/6564)

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**Author:** [@Hao](https://discourse.radiance-online.org/u/Hao)\
**Replies:** 4\
**Last updated:** [May 13, 2024, 11:45pm UTC](https://discourse.radiance-online.org/t/what-kind-of-file-formate-is-better-for-radiance-from-the-revit/6564 "2024-05-13T23:45:01Z")

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Hi everyone, I have been learning the Radiance recently. I encountered a question that I build a 3D model of a building in Revit and I want to export the model and import it in Radiance for lighting analysis. I learned …

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## [Periodic Boundary Condition for Radiance geometry](https://discourse.radiance-online.org/t/periodic-boundary-condition-for-radiance-geometry/6568)

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**Author:** [@Ravi\_Bharti](https://discourse.radiance-online.org/u/Ravi_Bharti)\
**Replies:** 1\
**Last updated:** [May 13, 2024, 5:29pm UTC](https://discourse.radiance-online.org/t/periodic-boundary-condition-for-radiance-geometry/6568 "2024-05-13T17:29:22Z")

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I have a complex 3d model of a tree, I need to find the incident radiation on the ground below the tree. What makes it computationally expensive for me is the incident radiation below it will also depend on the surroundi…

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## [How to add a light source with reflectance?](https://discourse.radiance-online.org/t/how-to-add-a-light-source-with-reflectance/6557)

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**Author:** [@bzxgcs](https://discourse.radiance-online.org/u/bzxgcs)\
**Replies:** 10\
**Last updated:** [May 12, 2024, 3:14am UTC](https://discourse.radiance-online.org/t/how-to-add-a-light-source-with-reflectance/6557 "2024-05-12T03:14:32Z")

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Hi everyone, I’m a novice of radiance. I tried to calculate indirect illuminance in a room illuminated by a large surface light source (bright polygon). However, the “light” material has no reflectance property. This res…

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## [How can I visualize the ray in the rendering picture](https://discourse.radiance-online.org/t/how-can-i-visualize-the-ray-in-the-rendering-picture/6559)

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**Author:** [@1112](https://discourse.radiance-online.org/u/1112)\
**Replies:** 2\
**Last updated:** [May 11, 2024, 5:49pm UTC](https://discourse.radiance-online.org/t/how-can-i-visualize-the-ray-in-the-rendering-picture/6559 "2024-05-11T17:49:20Z")

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How can I visualize the ray in the rending picture with radiance, just like below picture?

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## [How to use cnt(), rtrace() command under Pyradiance](https://discourse.radiance-online.org/t/how-to-use-cnt-rtrace-command-under-pyradiance/6551)

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**Author:** [@Hao](https://discourse.radiance-online.org/u/Hao)\
**Replies:** 2\
**Last updated:** [May 10, 2024, 4:33am UTC](https://discourse.radiance-online.org/t/how-to-use-cnt-rtrace-command-under-pyradiance/6551 "2024-05-10T04:33:42Z")

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Hi everyone, I am not sure if I can ask some questions related to Pyradiance here. I followed the tutorial from the Pyradiance website (Quickstart - Pyradiance Docs) and it works. But for the Reference, there are some c…

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## [Is there a faster way to calculate the illuminance value?](https://discourse.radiance-online.org/t/is-there-a-faster-way-to-calculate-the-illuminance-value/6547)

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**Author:** [@Hao](https://discourse.radiance-online.org/u/Hao)\
**Replies:** 7\
**Last updated:** [April 29, 2024, 3:20am UTC](https://discourse.radiance-online.org/t/is-there-a-faster-way-to-calculate-the-illuminance-value/6547 "2024-04-29T03:20:47Z")

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Hi everyone, Based on the tutorial material, I learned the way to calculate the illuminance value of the points of the working plane is as follows. The working plane is 0.8 above the floor. cat points3.pts | rtrace -h …

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## [What's the default value of -ab option of rtrace](https://discourse.radiance-online.org/t/whats-the-default-value-of-ab-option-of-rtrace/6546)

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**Author:** [@Hao](https://discourse.radiance-online.org/u/Hao)\
**Replies:** 4\
**Last updated:** [April 27, 2024, 6:22am UTC](https://discourse.radiance-online.org/t/whats-the-default-value-of-ab-option-of-rtrace/6546 "2024-04-27T06:22:52Z")

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Hi everyone, I read manual pages for rtrace, for the "-ab ", it show as follows: " This value defaults to 1 in photon mapping mode (see -ap below), implying that global photon irradiance is always computed via one am…

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## [The problem of the gendaymtx](https://discourse.radiance-online.org/t/the-problem-of-the-gendaymtx/6542)

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**Author:** [@1112](https://discourse.radiance-online.org/u/1112)\
**Replies:** 8\
**Last updated:** [April 26, 2024, 11:13pm UTC](https://discourse.radiance-online.org/t/the-problem-of-the-gendaymtx/6542 "2024-04-26T23:13:07Z")

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When using gendaymtx to generate the sky matrix, it was observed that non-zero luminance values for each sky patch can still be outputted even when the solar altitude is less than 0. The input file is as follows: input …

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## [How to read the rad file of luminaries generated by ies2rad and how change the lumen output of a luminaire by modifying the rad file？](https://discourse.radiance-online.org/t/how-to-read-the-rad-file-of-luminaries-generated-by-ies2rad-and-how-change-the-lumen-output-of-a-luminaire-by-modifying-the-rad-file/6543)

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**Author:** [@Hao](https://discourse.radiance-online.org/u/Hao)\
**Replies:** 2\
**Last updated:** [April 26, 2024, 1:17am UTC](https://discourse.radiance-online.org/t/how-to-read-the-rad-file-of-luminaries-generated-by-ies2rad-and-how-change-the-lumen-output-of-a-luminaire-by-modifying-the-rad-file/6543 "2024-04-26T01:17:54Z")

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Hi all, Recently, I used ies2rad to read the ies file and got two files- rad and data file. Part of the rad file is shown as follows and I am confused about the fourth line. The 0.158 1.268 0.05 is the dimension of the…

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## [The means and functions of inputs for rtrace](https://discourse.radiance-online.org/t/the-means-and-functions-of-inputs-for-rtrace/6526)

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**Author:** [@Hao](https://discourse.radiance-online.org/u/Hao)\
**Replies:** 7\
**Last updated:** [April 25, 2024, 3:41am UTC](https://discourse.radiance-online.org/t/the-means-and-functions-of-inputs-for-rtrace/6526 "2024-04-25T03:41:06Z")

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Hi everyone, I am new to Radiance and I have been learning the rtrace command recently. Based on the introduction of radiance\_tutorial.pdf and manual pages, for the input of rtrace, the first 3 inputs are the coordinate…

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## [rcontrib with arbitrary light source positions](https://discourse.radiance-online.org/t/rcontrib-with-arbitrary-light-source-positions/6538)

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**Author:** [@SamGianni](https://discourse.radiance-online.org/u/SamGianni)\
**Replies:** 2\
**Last updated:** [April 22, 2024, 8:44am UTC](https://discourse.radiance-online.org/t/rcontrib-with-arbitrary-light-source-positions/6538 "2024-04-22T08:44:30Z")

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Hello, I am new here and I hope to find someone that can guide me with the following problem. I am trying to use rcontrib to calculate daylight coefficients for light sources at arbitrary positions. From several tutor…

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## [How to set fish-eye view with rvu](https://discourse.radiance-online.org/t/how-to-set-fish-eye-view-with-rvu/6529)

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**Author:** [@Hao](https://discourse.radiance-online.org/u/Hao)\
**Replies:** 2\
**Last updated:** [April 19, 2024, 1:12am UTC](https://discourse.radiance-online.org/t/how-to-set-fish-eye-view-with-rvu/6529 "2024-04-19T01:12:09Z")

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Hi everyone, I am new to Radiance. Recently I have been trying how to set a fish-eye view. I read the man page of rvu. But I am still confused about how to set a fish-eye view when we view the scene interactively with r…

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## [Does the type of Patterns for primitives can only be used to build distribution of material?](https://discourse.radiance-online.org/t/does-the-type-of-patterns-for-primitives-can-only-be-used-to-build-distribution-of-material/6522)

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**Author:** [@Hao](https://discourse.radiance-online.org/u/Hao)\
**Replies:** 6\
**Last updated:** [April 19, 2024, 12:38am UTC](https://discourse.radiance-online.org/t/does-the-type-of-patterns-for-primitives-can-only-be-used-to-build-distribution-of-material/6522 "2024-04-19T00:38:39Z")

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Hi everyone, I am learning Radiance now. With the radiance\_tutorial.pdf, I learned that there are 4 basic types of primitives. I have a question about the Textures and Patterns. Do they only be used to define the distri…

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## [Question about the use of xform in a exercise in the radiance\_cookbook](https://discourse.radiance-online.org/t/question-about-the-use-of-xform-in-a-exercise-in-the-radiance-cookbook/6527)

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**Author:** [@Hao](https://discourse.radiance-online.org/u/Hao)\
**Replies:** 2\
**Last updated:** [April 19, 2024, 12:34am UTC](https://discourse.radiance-online.org/t/question-about-the-use-of-xform-in-a-exercise-in-the-radiance-cookbook/6527 "2024-04-19T00:34:19Z")

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Hi everyone, I am following the radiance\_cookbook.pdf to learn about radiance. But for the exercise at p12: there is a exercise to use xform command to a array of fittings: $ cat lights.rad !xform -t 1 1 2.95 -a 3 -t…

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## [Question about the falsecolor in the exercise of Radiance\_tutoral.pdf Chapter 5 p35](https://discourse.radiance-online.org/t/question-about-the-falsecolor-in-the-exercise-of-radiance-tutoral-pdf-chapter-5-p35/6520)

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**Author:** [@Hao](https://discourse.radiance-online.org/u/Hao)\
**Replies:** 3\
**Last updated:** [April 17, 2024, 3:16pm UTC](https://discourse.radiance-online.org/t/question-about-the-falsecolor-in-the-exercise-of-radiance-tutoral-pdf-chapter-5-p35/6520 "2024-04-17T15:16:19Z")

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Hi everyone, I am new to Radiance and am following the tutorial material to learn it. But for the command in p35 as follows. I do not find anywhere in the book to introduce how to generate “scene\_i.hdr”. " falsecolor …

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## [How to use trad](https://discourse.radiance-online.org/t/how-to-use-trad/6521)

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**Author:** [@Hao](https://discourse.radiance-online.org/u/Hao)\
**Replies:** 2\
**Last updated:** [April 17, 2024, 2:01am UTC](https://discourse.radiance-online.org/t/how-to-use-trad/6521 "2024-04-17T02:01:21Z")

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Hi everyone, I am learning Radiance recently and when I follow the radiance\_tutorial to use the following command. trad it shows the following error, does anyone know how to install trad. Kind regards, Hao $ trad …

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## [Radiance\_tutoral question](https://discourse.radiance-online.org/t/radiance-tutoral-question/6515)

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**Author:** [@Hao](https://discourse.radiance-online.org/u/Hao)\
**Replies:** 11\
**Last updated:** [April 15, 2024, 10:51am UTC](https://discourse.radiance-online.org/t/radiance-tutoral-question/6515 "2024-04-15T10:51:35Z")

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Hey everyone, I am new to Radiance. I am following the tutorial material: radiance\_tutorial, subsection 2.2.3 More Complex Scenes, page 15. For step 4, I add the command “! genbox glazing\_mat glass 4 0 3” in room.rad fi…

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## [Octree generation: oconv -n and -r options](https://discourse.radiance-online.org/t/octree-generation-oconv-n-and-r-options/6510)

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**Author:** [@Funerus](https://discourse.radiance-online.org/u/Funerus)\
**Replies:** 1\
**Last updated:** [April 7, 2024, 3:37pm UTC](https://discourse.radiance-online.org/t/octree-generation-oconv-n-and-r-options/6510 "2024-04-07T15:37:51Z")

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Hey everyone, I’ve been experimenting with the oconv settings to try and cut down the time it takes to generate an octree. It seems like two settings, -n and -r, are key factors here. 1) With default settings - 60s: Wh…

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## [Questions about rcontrib compared to rtrace, and few more things](https://discourse.radiance-online.org/t/questions-about-rcontrib-compared-to-rtrace-and-few-more-things/6499)

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**Author:** [@Inwoo](https://discourse.radiance-online.org/u/Inwoo)\
**Replies:** 3\
**Last updated:** [April 1, 2024, 5:09pm UTC](https://discourse.radiance-online.org/t/questions-about-rcontrib-compared-to-rtrace-and-few-more-things/6499 "2024-04-01T17:09:18Z")

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Hello, I’m seeking advice from experts on using rcontrib for my tasks, as I’m encountering lower illuminance values compared to rtrace. Here’s what I’m doing: I’m rendering scenes with different solar positions for diff…

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## [Different BSDFs generated using the same CFS](https://discourse.radiance-online.org/t/different-bsdfs-generated-using-the-same-cfs/6498)

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**Author:** [@Xuran](https://discourse.radiance-online.org/u/Xuran)\
**Replies:** 4\
**Last updated:** [March 30, 2024, 3:38am UTC](https://discourse.radiance-online.org/t/different-bsdfs-generated-using-the-same-cfs/6498 "2024-03-30T03:38:06Z")

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Dear Radiance Experts, I am a PHD student who is using genBSDF to generate the BSDF of a CFS to analyze DGP. For convenience, I represented the entire louver system with a single louver. However, I also compared this to…

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## [DGP measured significantly lower by evalglare](https://discourse.radiance-online.org/t/dgp-measured-significantly-lower-by-evalglare/6497)

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**Author:** [@JUNYOUNG](https://discourse.radiance-online.org/u/JUNYOUNG)\
**Replies:** 8\
**Last updated:** [March 26, 2024, 4:35am UTC](https://discourse.radiance-online.org/t/dgp-measured-significantly-lower-by-evalglare/6497 "2024-03-26T04:35:39Z")

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hello everyone! I am a college student who wants to use evalglare to measure DGP. I want to measure the DGP value by taking a picture through the Raspberry Pi camera and converting it to HDR image, but it is measuring …

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## [Why does the rendering time of vways-rcontrib vary with image resolution, but rpic doesn't?](https://discourse.radiance-online.org/t/why-does-the-rendering-time-of-vways-rcontrib-vary-with-image-resolution-but-rpic-doesnt/6403)

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**Author:** [@1112](https://discourse.radiance-online.org/u/1112)\
**Replies:** 3\
**Last updated:** [March 23, 2024, 3:06pm UTC](https://discourse.radiance-online.org/t/why-does-the-rendering-time-of-vways-rcontrib-vary-with-image-resolution-but-rpic-doesnt/6403 "2024-03-23T15:06:47Z")

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I compared the rendering time when rendering the images of different resolutions, and found that the rendering time reduced significantly with the decrease of the resolution of the rendering images using vways-rcontrib, …

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