What I'm doing wrong? (Rope lighting, GPU raytrace)

[KirillP]

Hi, Happy New Year!

New year, old problems. I'm trying to simulate a LED strip general lighting (not under cabinet, but more like Davide Groppi from Italy creates). The following rendering is made at 11pm, so no ambient light, all rooms are off except this one (kitchen), it's 266 sq. ft. and has 18 recessed lights of 600 lm each and a rope light. Rope light has 450lm per foot and 21 feet long, so about 9000 lm. Rope light is of point spot type (because strips emit in one direction) with a cut off angle of 170 deg and drop off rate of 0 (for simplicity). 

1. Why the heck it's still so dark?

2. Why the heck there's a very visible shadow line on the wall to the right?

I watched, I believe, all the videos and tried all combinations of parameters. I can only make it look worse from this point. The 266 sq ft room should look much brighter with 20k lumens in it, am I right? This is about 2x of normal kitchen lighting or 1x of kitchen workspace lighting. It should be flooded with light.

(rendering made on a windows machine with RTX 4090 and 100 samples)

Any ideas?
 

Thanks,

Kirill

Edited January 7 by KirillP
s/point/spot

[mtldesigns]

1 hour ago, KirillP said:

Happy New Year!

I am no expert on this, not even close..  I too have struggled with rooms that should be bright as day but look dark, like yours.  My observations are this:

• Why does the rope light look like its hanging at door height?  Causing that shadow line, I assume, because the light is facing down.
• All the can lights appear to be in the soffit and none in the actual ceiling?  Lights aim down, meaning the main ceiling will look dark.
  • move some of the 18 to the ceiling.  I think 18 is way to many.
• Is this a  PBRT?
• I set my lights at 2850 lums max in this situation..  just to get a descent camera view.
• I have my samples set at 500.  With your machine, it shouldn't take long either.  My denoise is checked and I max out the brightness to 100.00.  All done in the render technique Options DBR.

 

Hope this helps some, and I hope the PBRT pros chime in too..  I'd like to know myse;f.

[Kbird1]

11 hours ago, KirillP said:

450lm per foot and 21 feet long

 

And what is your MAX Lights Set to for the Default Lighting Set ?    Multiply the number of lights per foot ( see Light Data specs)  x 21'  + your Downlights etc  

 

Ropelights quickly eat up the Default Max Settings....

 

* In a Plan I had PBR Performance Issues with recently Chief Tech. Support found the Lighting Engine was still doing the Lighting in Rooms other that where the camera was (Kitchen) even though they unchecked, and one of the Killers was the Rope lighting and a lit Mirror in the Powder Rm. , the solution was to put those Lights on a custom Layer and turn the Layer off.

 

M. 

[KirillP]

15 hours ago, mtldesigns said:

 

Quote

• Why does the rope light look like its hanging at door height?  Causing that shadow line, I assume, because the light is facing down.

It's actually higher than the doorway, half way between the top of the doorway and the bottom of the window. This section of the house has a higher ceiling and the ropes are supposed to hang a bit above the ceiling height of the surrounding areas. That doorway is 8' high, like the rest of the "old house". This is a heavy remodel of a reinforced concrete house built in 1971 with 8' ceilings and this one section is 10' high. Suffice to say that Chief Architect is not making it (remodeling concrete houses) easy :-) "Tell me you developed the software in the USA, without telling me you developed it in the USA" © lol. 

It's a rope light, so the shadow to the right of the picture shouldn't be there. There's nothing in the way of the light ray between the rope light and the wall next to the electric panel.

Quote

• All the can lights appear to be in the soffit and none in the actual ceiling?  Lights aim down, meaning the main ceiling will look dark.
  • move some of the 18 to the ceiling.  I think 18 is way to many.

I'm fine with the ceiling being darker, in a way it's the effect I'm after. What I do not understand is the insufficient lighting on the work surface below them. The kitchen is supposed to be around 40 ft. cd. with another 40 ft. cd. for the work surfaces. 18 is definitely many-ish, but where's the effing light?!? With this amount of lighting I should be able to do neurosurgery on this work surface.

Quote

• Is this a  PBRT?

Yessir. 

Quote

• I set my lights at 2850 lums max in this situation..  just to get a descent camera view.

I can do that too, but I'm trying to simulate a realistic scenario with the lights I'll have. I can make it look good with absolutely unrealistic numbers, but then it's not a photorealistic rendering, right? The "realistic" piece is missing. Brightness and exposure don't really cut it because then the area around the rope light becomes completely washed out. It looks like that the light falloff is completely wrong, despite being turned off completely.

Quote

I have my samples set at 500.  With your machine, it shouldn't take long either.  My denoise is checked and I max out the brightness to 100.00.  All done in the render technique Options DBR.

It doesn't affect the rendering fidelity, just takes longer. I tried 300, I tried 1000, etc.

 

[KirillP]

5 hours ago, Kbird1 said:

 

And what is your MAX Lights Set to for the Default Lighting Set ?    Multiply the number of lights per foot ( see Light Data specs)  x 21'  + your Downlights etc  

Default is set to 5000, way above I have in the house total. This rendering was made with a custom light set though. I only have two more rope lights in the room next to this one, 30' total and they were manually turned off at the time of this rendering. When they are on I see it because they shine like nuclear blast through the right doorway (they are waaaay too bright, and need to be adjusted).

But it's an interesting data point about the engine, thanks!

[Kbird1]

3 hours ago, KirillP said:

Default is set to 5000, way above I have in the house total. This rendering was made with a custom light set though. I only have two more rope lights in the room next to this one, 30' total and they were manually turned off at the time of this rendering. When they are on I see it because they shine like nuclear blast through the right doorway (they are waaaay too bright, and need to be adjusted).

But it's an interesting data point about the engine, thanks!

 

The next suggestion I had was actually a Custom Light Set but you have already done that and increased the Max lights from the default 20 and so the Next thing to do is post the Plan if possible so People can have a "play"  ( Forum is limited to 14mb ) or send it to Tech. Support for a Look while yo work on other Things/Projects , they are pretty responsive I have found.

 

M.

[ProPlan_2011]

I regularly struggle with lighting when flipping between interior and exterior PBR.  I personally find it easier to play with the exposure.  Try enabling manual exposure and crank up until satisfied.

[KirillP]

On 1/2/2024 at 3:47 PM, ProPlan_2011 said:

I regularly struggle with lighting when flipping between interior and exterior PBR.  I personally find it easier to play with the exposure.  Try enabling manual exposure and crank up until satisfied.

I don't want the picture to just look nice, I want it to look realistic. Cranking up exposure will just wash out the lit areas above. My problem in this picture is the light intensity which falls off too quickly to be realistic (unless we're shooting these pictures underwater).

[DeLayDesign]

14 hours ago, KirillP said:

I don't want the picture to just look nice, I want it to look realistic. Cranking up exposure will just wash out the lit areas above. My problem in this picture is the light intensity which falls off too quickly to be realistic (unless we're shooting these pictures underwater).

Can you share your plan file with us?  It might be easier to sort out what the issue is.

I think your issue is your drop off rate - which is causing the harsh shadow against the wall.  Below is what the light looks like as a spot light with a 'zero' drop off rate (12" between lights") - which is what I think you meant to say when you said lights are 'point' lights.

 

Drop off rate of 3:
 

 

This is what spot light with a drop off of 7.5 (Default) looks like:

 

 

This is what it looks like as a point light (no direction)

 

 

[KirillP]

On 1/5/2024 at 2:45 AM, DeLayDesign said:

Can you share your plan file with us?  It might be easier to sort out what the issue is.

I think your issue is your drop off rate - which is causing the harsh shadow against the wall.  Below is what the light looks like as a spot light with a 'zero' drop off rate (12" between lights") - which is what I think you meant to say when you said lights are 'point' lights.

 

Oops, I meant "Spot" lights, not "Point". Point lights do not have cut off angle and no direction. OP fixed.

 

I can't see the screenshot of your Light Data dialog, it's too compressed, but I believe you have lumens in the thousands too. My light has similar settings to your first picture. Does it look realistic to you? You have a few thousand lumens handing a few feet above the floor and you don't even see the effect on this floor.

I figured that I misunderstood the "Drop off rate" setting, it's the diffusion on the light's aperture, how soft or sharp the edge of the spot looks like, so zero drop off should generate a visible cone on the wall parallel to the light direction and it's indeed visible on your first picture and on mine. But still it doesn't explain why no matter how bright the rope is, it doesn't contribute significantly to the brightness of the room.

 

I became so obsessed with this problem that I've ordered some led strips and a power supply to run an experiment IRL.

 

Thanks!

[Kbird1]

1 hour ago, KirillP said:

I can't see the screenshot of your Light Data dialog, it's too compressed, but I believe you have lumens in the thousands too

 

Yep weirdly compressed but I think it says 450 lumen.

 

On 1/4/2024 at 7:39 AM, KirillP said:

I don't want the picture to just look nice, I want it to look realistic

 

Chief can look pretty good but it can't do Photo Realistic  (Yet?)

 

Providing the Plan as several have mentioned is the only way anyone can help really, as we need to "Play" in your Plan , with your Settings etc to figure it out ...if it can be...

 

M.

[DeLayDesign]

Hi @KirillP  My lumens are 450.0

[KirillP]

On 1/7/2024 at 4:12 PM, Kbird1 said:

 

Chief can look pretty good but it can't do Photo Realistic  (Yet?)

 

Providing the Plan as several have mentioned is the only way anyone can help really, as we need to "Play" in your Plan , with your Settings etc to figure it out ...if it can be...

 

 

Well, they say "Physically Based", and I was doing raytracing back in the 90x and it was pretty good even back then. It just took weeks what now takes a minute on a 4090....

 

Promise you're not going to steal my genius design! Srsly, thanks for volunteering to look at this. Not sure if the camera position is saved in the plan, so I'm attaching the screenshot of how it's positioned, sunlight has to be off. I've added a second rope just to see if it makes any difference. I've stripped the zip from materials that not needed and removed other rooms, to squeeze into 14Mb limit.

plan.zip

[Kbird1]

2 hours ago, KirillP said:

I've stripped the zip from materials that not needed and removed other rooms, to squeeze into 14Mb limit.

 

If you have stripped it as far as the pic above seems to indicate, the Lighting in PBR won't work as expected as the building is no longer complete without rooms etc so you may need to provide a link to OneDrive or Google Drive etc instead.

 

* I took a quick look and it is pretty badly 'broken'

 

M.

[KirillP]

16 hours ago, Kbird1 said:

If you have stripped it as far as the pic above seems to indicate, the Lighting in PBR won't work as expected as the building is no longer complete without rooms etc so you may need to provide a link to OneDrive or Google Drive etc instead.

36Mb

https://www.icloud.com/iclouddrive/0d5EoHKsUNCFLkuvJ5pP_ahAg#plan

[robdyck]

On 1/1/2024 at 3:08 PM, KirillP said:

1. Why the heck it's still so dark?

2. Why the heck there's a very visible shadow line on the wall to the right?

I watched, I believe, all the videos and tried all combinations of parameters.

There are so many factors that affect these renderings. A person really needs to spend a lot of time learning and evaluating the effects of various camera settings, light settings and material adjustments. Not to mention the model needs to be thoroughly and accurately detailed so that the model quality is in tune with the desired rendering quality. 

Trouble shoot 1 or 2 items at a time by critically examining what is wrong and how to fix it. For example; review the stainless steel material on the fridge and compare it to your own fridge or a real photo of a stainless fridge; does it look close to the same? If you used a Chief library material, then probably not. It's probably not quite the right color, it's probably too light and overly rough so experiment with material settings until the material preview (using physically based rendering) looks pretty good. Then save and move on to the next material. 

 

Is the entire interior almost all one material? Is that working? Maybe experiment using various settings of white materials for walls, ceilings, doors, trim, etc.

Do the faucets look real to you? If not, replace them or adjust them, etc.

 

 

 

 

[KirillP]

6 minutes ago, robdyck said:

There are so many factors that affect these renderings. A person really needs to spend a lot of time learning and evaluating the effects of various camera settings, light settings and material adjustments.

 

Many factors which are not obvious to me. You got really stunning pictures out of my plan, they look awesome, but I'm not after awesomeness. I'm after visual fidelity. I'm trying to use CA as a light modelling tool, because I never worked with powerful LED light ropes and want to use them as one of primary light sources. 

You did an awesome job filling the house with ambient sunlight, but I'm intentionally render with all lights off, except the ones I'm interested in, and at total ambient darkness.

 

How did you get the stainless steel so good?

 

I use all materials stock from CA, except for the countertop and cabinetry, where I use hi res textures downloaded from the manufacturers websites. These look pretty decent to me (you made wood too shiny, in reality it's more matte like in my picture, but more color saturated like in yours).

[robdyck]

For night time scenes, the same views look pretty good with the sunlight toggled off. As for lighting reality, I suppose it's pretty tough to say if Chief can reproduce the light settings on a per lumen basis close enough to use as a predictive tool for specifying the amount of light. 

I'd probably start in a Chief model of my home office and see if it looks close to realistic using the exact same light sources. I'd then evaluate the accuracy and make some notes.

 

Stainless Steel: reduce both roughness values significantly (U:30 / V:10) and alter the material color to something much darker and on a black/white scale (122/122/122).

[KirillP]

6 hours ago, robdyck said:

 

Now you see what bothers me - the light from the rope shines onto the tops of the doors and then falls off very quickly. It behaves like light underwater but without scattering. Lumens-shlumens, but the basic physics is wrong from my perspective, light in the air falls off much slower.

 

Thanks for the SS tips, will try them ASAP, the dull looks of SS is very annoying.

[GeneDavis]

Where was the idea of the dead-straight no-sag rope light, no housing, sourced?  The images show it positioned for general lighting along the two passage and work lanes, but that seems like the wrong approach for such lighting.

 

I see it and use it in recessed ceiling coves, atop wall cabinets, for undercab countertop lighting, and inside cabinets that have glass doors.

 

Have you any photos of rope lighting used in the way you have modeled it?

[Renerabbitt]

On 1/4/2024 at 7:39 AM, KirillP said:

I don't want the picture to just look nice, I want it to look realistic. Cranking up exposure will just wash out the lit areas above. My problem in this picture is the light intensity which falls off too quickly to be realistic (unless we're shooting these pictures underwater).

You've touched on some crucial points about the intricacies of real-time ray tracing engines, but we are dealing with single path trace environments. Absolutely, better contrast in evenly lit scenes is achievable, but it does require tweaking the exposure settings. This is where Ambient Occlusion (AO) maps become vital. They help in maintaining the right black levels in unlit and occluded areas.

The complexity increases with single path tracing, particularly when integrating specific lighting types like under counter lights. These are designed for low light projection and we'rent designed to be used as soffit lighting. OOTB 4-inch intervals can create challenges due to overlapping light data. The engine, having to choose a single light source, can indeed result in unrealistic overhead lighting effects.The better approach would be to revert back to point lights and make a light shield for uniform lighting.
You could try to switch  emitters to 24 inches apart makes sense for a more accurate representation. Adjusting the drop-off rate to 1 or 1.5 for a 170-degree cut, coupled with an rope lights with a 60-degree cut-off and a drop-off rate of 4, seems like a sound approach. From there, fine-tuning lumens and exposure will be key. Still think point light with a shield is a better option

Understanding the behavior of single light traces is critical. They recognize lit surfaces but not the specific light source, leading to the engine picking an emitter based on its algorithm. For more precise lighting, transitioning to a CPU ray trace or another rendering engine might be necessary, as single light traces typically employ a Monte Carlo method which can be limited in these scenarios.

[KirillP]

On 1/12/2024 at 4:28 PM, GeneDavis said:

Where was the idea of the dead-straight no-sag rope light, no housing, sourced?  The images show it positioned for general lighting along the two passage and work lanes, but that seems like the wrong approach for such lighting.

 

Have you any photos of rope lighting used in the way you have modeled it?

 

One of the off the shelf implementations, cheap and relatively low power, but shows the general idea of technical implementation: https://www.casalolalights.com/products/skyline-linear-led-lighting?_pos=1&_psq=skyline&_ss=e&_v=1.0

 

Designer, who I lifted the idea from: https://www.davidegroppi.com/es/productos/infinito-p262 (warning, it's a designer website. the number of javascript gimmicks is on par with his original ideas).

[KirillP]

23 hours ago, Renerabbitt said:

You've touched on some crucial points about the intricacies of real-time ray tracing engines, but we are dealing with single path trace environments. Absolutely, better contrast in evenly lit scenes is achievable, but it does require tweaking the exposure settings. This is where Ambient Occlusion (AO) maps become vital. They help in maintaining the right black levels in unlit and occluded areas.

I kinda vaguely remember these details from my 3D years, but here I believe we have a much simpler task. Look at my original picture: why is so much difference between the red and green area? And even more between green and blue? They are lit directly, with the lights right above them (and from the sides too), there's no ambient occlusion happening whatsoever.  

[Renerabbitt]

2 hours ago, KirillP said:

I kinda vaguely remember these details from my 3D years, but here I believe we have a much simpler task. Look at my original picture: why is so much difference between the red and green area? And even more between green and blue? They are lit directly, with the lights right above them (and from the sides too), there's no ambient occlusion happening whatsoever.  

Simply put, this is how the spot light was designed. Keeping in mind that this software is a multi renderer unlike a dedicated rendering plugin, lighting has to look good in standard as well as CPU ray trace and again this is a single path trace.  I can’t tell you exactly why it was designed this way but I have a good idea. If you turn off all lights, ambient light with some good materials makes for a great rendering.. so I imagine the point light is simply to fake a beam spread similar to an IES profile. Try this for instance, set your lights color to red and see how it affects the room… then switch to a point light.

[KirillP]

17 hours ago, Renerabbitt said:

Simply put, this is how the spot light was designed. Keeping in mind that this software is a multi renderer unlike a dedicated rendering plugin, lighting has to look good in standard as well as CPU ray trace and again this is a single path trace.  I can’t tell you exactly why it was designed this way but I have a good idea. If you turn off all lights, ambient light with some good materials makes for a great rendering.. so I imagine the point light is simply to fake a beam spread similar to an IES profile. Try this for instance, set your lights color to red and see how it affects the room… then switch to a point light.

This makes sense indeed, but kind of sad. I'd expect a focus on fidelity from the professional architectural software. My wife helps me with a great iPad app called Live Home 3D, she just plays around there and shows me the ideas, then places object roughly where she wants them and I calculate and place them on the correct spots/grids/etc in CA. There, 3D render should look decent no matter what you do, because almost 100% of users don't know what they are doing. In CA though, I'd expect the picture to be a black rectangle if I switch all the lights off and turn the ambient off too. 

 

I received a few first samples of LED strips that I'm going to use and duct taped a test environment in the rental I'm living in now. Same 450 lm/ft, almost the same height as it will be in the future house, Less ambient light (coming not from the LED strip) than in the render. The lighting on the wall looks like nothing on the render. (sorry for the mess). Total length of the strip is 16.4'