constant hot spot on blinds BSDF

[Eric Shadd]

A venetian blind BSDF I created has a spot that lets light through no matter what the incident angle is. I've attached relevant pictures and files for inputs and outputs. TIA!

[Jacob C. Jonsson (LBNL)]

I am assuming you are talking about the outgoing 20 degree "down" patch.

It seems to be a hotspot from the scattering from the blinds. If you have light incident parallel with the blinds you will notice there is no light in that patch, so there has to be interaction with the surfaces. 

Figures 11-25 and 11-26 in the WINDOW technical documentation indicate that there is a maximum in outgoing transmittance in the downward direction, Psi_max,1, but that should have depend more on the angle of incidence. So it is a bit of a mystery to me why this patch is getting slightly more light. 

1, Is this only tied to command line version?

2. Do you see it when you combine it with real glass?

3. Is it always located in zero-slat tilt angle?

4. The number seems really small (<0.5%, but up to 7x greater than neighboring patches), how significant do you consider this problem?

[Eric Shadd]

Thanks for the reply!

Yeah, I’m talking about the 20 degree down patch and actually the patch is there no matter whether incident light is parallel or not. I have images for all vertical incident patches and they all have an outgoing patch in that same 20 degree down patch. Also, I’ve made 120 Venetian BSDFs with different tilts and spacing and they all have this patch in the same spot. 

1. No, it’s also happening running Calc in the Window7 app but I do get the error “Glazing System 219. Calculation Error: IGU cavity height must be greater than zero”

2. Yup, just tried with glass 103 and had same patch and same error as above.

3. Nope, it’s showing up on all tilt angles 0 -20. The example Venetian I gave has a tilt of 20.

4. I only consider it significant because it’s consistent for all the BSDFs and to me that makes my spidey sense tingle around the results as a whole. Also, I did something similar a year ago and didn’t get this behavior.

--
You can view the WINDOW forum online at: http://windows.lbl.gov/software/WINDOW/forum
---
You received this message because you are subscribed to the Google Groups "Berkeley Lab WINDOW" group.
To unsubscribe from this group and stop receiving emails from it, send an email to berkeley-lab-wi...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/berkeley-lab-window/11be24c5-375a-4f31-8861-25c27f6a7e0f%40googlegroups.com.

[Eric Shadd]

FYI I fixed the cavity height error by entering an IG Height and Width in the Window7 app but the patch is still there. I also used the W6Matrix reader spreadsheet and verified that it’s not an error with BSDFViewer.

On a side note, the command line manual says the default IG Height and Width are 1000 mm but they turned out to be 0 mm as you can see from the files I posted.

On Aug 27, 2019, at 1:35 PM, Jacob C. Jonsson (LBNL) <jcjo...@lbl.gov> wrote:

--

[Robin Mitchell]

Eric

What version of WINDOW are you running? 

Robin

To view this discussion on the web visit https://groups.google.com/d/msgid/berkeley-lab-window/00B8E5E0-B06F-4A5C-A3B4-6669DE9AB168%40gmail.com.

--

Robin Mitchell

Building Technology and Urban Systems Division
Energy Technologies Area
Lawrence Berkeley National Laboratory

[Jacob C. Jonsson (LBNL)]

On Tuesday, August 27, 2019 at 2:28:11 PM UTC-7, Eric Shadd wrote:

Yeah, I’m talking about the 20 degree down patch and actually the patch is there no matter whether incident light is parallel or not. I have images for all vertical incident patches and they all have an 

Odd, when I look at your file and set incident parallel to the blind I do get 0.0% in suspicious spot.

[Eric Shadd]

Ah yes, shining light up to make parallel to blinds. My mistake. Yes I get the same result.

<paralle.png>

--
You can view the WINDOW forum online at: http://windows.lbl.gov/software/WINDOW/forum
---
You received this message because you are subscribed to the Google Groups "Berkeley Lab WINDOW" group.
To unsubscribe from this group and stop receiving emails from it, send an email to berkeley-lab-wi...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/berkeley-lab-window/cdb1e983-929c-405e-aa5d-56a900bca714%40googlegroups.com.

<paralle.png>

[Eric Shadd]

Hi Robin, sorry for the late reply. Didn't see this. I'm running 7.7.07.

-Eric

On Tuesday, August 27, 2019 at 2:54:31 PM UTC-7, Robin Mitchell wrote:

Eric

What version of WINDOW are you running? 

Robin

On Tue, Aug 27, 2019 at 2:40 PM Eric Shadd <eric...@gmail.com> wrote:

FYI I fixed the cavity height error by entering an IG Height and Width in the Window7 app but the patch is still there. I also used the W6Matrix reader spreadsheet and verified that it’s not an error with BSDFViewer.

On a side note, the command line manual says the default IG Height and Width are 1000 mm but they turned out to be 0 mm as you can see from the files I posted.

On Aug 27, 2019, at 1:35 PM, Jacob C. Jonsson (LBNL) <jcjo...@lbl.gov> wrote:

I am assuming you are talking about the outgoing 20 degree "down" patch.

It seems to be a hotspot from the scattering from the blinds. If you have light incident parallel with the blinds you will notice there is no light in that patch, so there has to be interaction with the surfaces. 

Figures 11-25 and 11-26 in the WINDOW technical documentation indicate that there is a maximum in outgoing transmittance in the downward direction, Psi_max,1, but that should have depend more on the angle of incidence. So it is a bit of a mystery to me why this patch is getting slightly more light. 

1, Is this only tied to command line version?

2. Do you see it when you combine it with real glass?

3. Is it always located in zero-slat tilt angle?

4. The number seems really small (<0.5%, but up to 7x greater than neighboring patches), how significant do you consider this problem?

On Tuesday, August 27, 2019 at 12:13:25 PM UTC-7, Eric Shadd wrote:

A venetian blind BSDF I created has a spot that lets light through no matter what the incident angle is. I've attached relevant pictures and files for inputs and outputs. TIA!

--
You can view the WINDOW forum online at: http://windows.lbl.gov/software/WINDOW/forum
---
You received this message because you are subscribed to the Google Groups "Berkeley Lab WINDOW" group.

To unsubscribe from this group and stop receiving emails from it, send an email to berkeley-lab-window+unsub...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/berkeley-lab-window/11be24c5-375a-4f31-8861-25c27f6a7e0f%40googlegroups.com.

--
You can view the WINDOW forum online at: http://windows.lbl.gov/software/WINDOW/forum
---
You received this message because you are subscribed to the Google Groups "Berkeley Lab WINDOW" group.

To unsubscribe from this group and stop receiving emails from it, send an email to berkeley-lab-window+unsub...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/berkeley-lab-window/00B8E5E0-B06F-4A5C-A3B4-6669DE9AB168%40gmail.com.