Hello dear dommunity,
I want to ask if is possible analyze the veiling glare on a screen through the Ladybug Tools, and if so, if you could give me some advice on how to proceed.
Unfortunately I have not found any topic about this question in the forum.
Thanks in advance
Hi @Jorn.Gunner.Lande ,
If you mean the āVeiling Luminanceā you can get this from the glare_indices output from the HB Glare Postprocess component.
See the point_in_time_view.gh file that downloads with Food4Rhino for a sample.
Thanks for the help chris
Hi Chris,
Iāve been using glare components version 1.6 for professional assessments for external glare (we use Veiling luminance) and have encountered some issues and questions.
1- Iām working with a 30-degree field of view for glare affecting train drivers, but setting the task angle to 30 degrees doesnāt behave as expected. Adjusting it to 60 degrees affects Veiling luminance results in a counterintuitive way and sometimes result in lower VL values. I considered changing the camera angle to 30, but the component requires a fisheye view. is there a way to either trim or only account for the luminance within the required angle?
2- In the assessment, we need to focus solely on the buildingās impact on glare (glare from reflected light only, and excluding the direct sun view). Disabling sun visibility doesnāt work as it will remove even its reflection.
3- There are peculiar behaviors with Radiance materials regarding the reflectance inputs. When I reduce material reflectance to 0 and maintain high specularity, I still encounter glare. values drop only when I reduce specularity. My research suggests that specularity is a FRACTION of the total reflection, but the results donāt align. (e.g., if Ref is 0.5 and Spec is 0.5 it should mean that the total specular reflection is 0.25).
4- Last but not least, is there a way to run imageless annual simulation for VL like what we have for DGP. I did find my way to make the definition run annually from a particular view. However this takes forever, as it is simply setting the component to keep running for 365 days.
I donāt know how to use Python, so any guidance or solutions you can provide would be greatly appreciated.
Hi @Hamzajh19 ,
I should first say that I really donāt know much about veiling luminance and my preferred glare metric is DGP. But I can say the following:
The Radiance evalglare function thatās being used to calculate VL requires a fisheye input to run successfully. I donāt know if thereās something inherent in the definition of VL that means it is only relevant for a 30-degree field of view, in which case Iād imagine that evalglare is automatically blocking out the rest of the image for this calculation. But I can tell you that evalglare wonāt give you any glare metrics unless you give it a fisheye image since the 180-degree FOV is important for DGP and the other glare metrics it computes. The task angle is not the field of view angle. Itās meant to represent where in the fisheye the task the person is working on is located.
I donāt know how you could do an accurate assessment of the scene contrast and its impact on glare using only the reflected light and not the rest of the light that comes from the sky. The contrast is just going to be very far from reality and ultimately not a great indicator of the actual likelihood that a person in the conditions will experience glare. I guess if you really needed something like this, you could run two Radiance simulations with different -ab and subtract the two images. But I would not expect evalglare to give me useful results with this image.
Those donāt seem peculiar to me. You may want to re-read the Radiance docs and read the Radiance forum to understand how Radiance interprets the specularity input since itās different than how you are describing it.
Thereās no support for computing VL with imageless annual glare. If you figure out how to implement it, we would be happy to have it.
Thanks for the quick response.
I do understand it only accepts fisheye. However I donāt understand how the results change when changing the task angle. it uses 30 degree as default and it is the desired angle for me. but apparently it is not blocking what is outside. to confirm this, I modelled a cone of vision geometry using LB component, and then retested a scene which had the sun on the peripheral of the image, and the Lveil dropped massively. And btw DGP is not applicable in our study for external spaces.
great idea about the -ab. I will try it out. however if I can at least exclude whatever is outside the 30 degrees representing the vision inside a vehicle for example, this will solve most of the issue.
from The RADIANCE 5.3 Synthetic Imaging System. I do understand from the screenshots that specularity is a fraction of the total either reflected or transmitted light.
What I donāt understand as well, is if I use a opaque, plastic or metal materials, I specularity is from 0-1. However if using Trans material (which I may use for glass to be able to control VLT and VLR), the component require all inputs aggregate to be 1ā¦ in addition the component doesnāt accept 1, but it only runs if the total (inputs = 0.99 or below).
These questions probably should have been broken down into several topics since weāre now pretty far from the original topic. For now, I will just respond to this one:
You are right that we are not being consistent in that the trans material is being created from_reflected_specularity but we donāt do the same for plastic or metal materials. I have added methods to make the plastic and metal materials this way:
ā¦ and I will make sure that these are used in the latest components.
Chris, that was very helpful, and it resolves any doubts. I have downloaded the 1.7 now from Food4rhino. The new Trans and Glass modifiers work, however, the Opaque and Metal has an error "1. Solution exception:ātypeā object has no attribute āfrom_reflected_specularityā
I have restarted to PC in case, but issue persists.
