Lightmaps not bright enough

Sarrus4x4 · February 9, 2023, 12:44pm

Hey, I am extremely new to Babylon and I found this thread when doing research on displaying residential units. Please forgive me if I am missing something obvious.
I am also not sure if I should ask this here or open a new thread

I have a question regarding the display of the used model. When comparing the output of: https://www.babylonjs-playground.com/#8EGGW2#2 and let’s say https://www.babylonjs-playground.com/#8EGGW2#9 the edges seem to be rounded (it all looks more natural). Does this all come from the use of Lightmaps or are there other tools/features being used to achieve that effect?
I tried to understand the Code from the Playgrounds but did not see where this ‘roundig’ effect is originating from.

Thank you in advance

sebavan · February 9, 2023, 4:36pm

Not really too sure what you mean by rounded, can you share a screenshot of both circling what you are looking into ?

By the way, Welcome to the community, we will find your answer ASAP !!!

joie · February 10, 2023, 11:29am

Hi there @sebavan

We have the very same problem with dark lightmaps.

Right now I’m using Nuke in order to tonemap the lightmap to force it fit inside the 0-1 range of 8bit PNG files.

You mentioned that RGBD fancy thing and we would want to understand that magic. Investigating a bit, it seems the “D” of that RGBD format is intended for depth, so personally I can’t understand how that would make PNG format to have broader luminance range.

Currently, the lightmap is generated in HDR file format, so we can do whatever is needed to it but to save it to PNG format and retain luminance values.

You wrote about that playground that converts HDR files into PNG RGBD format. But I can’t make it work.
Is there another way to create such wide range PNG formats?

Thanks in advance.

sebavan · February 10, 2023, 5:58pm

D stands for divisor and you can check the maths in our shaders:

github.com

sebavan/Babylon.js/blob/master/packages/dev/core/src/Shaders/ShadersInclude/helperFunctions.fx#L174-L197


      
          }

          

          // Check if configurable value is needed.

          const float rgbdMaxRange = 255.0;

          

          vec4 toRGBD(vec3 color) {

              float maxRGB = maxEps(max(color.r, max(color.g, color.b)));

              float D      = max(rgbdMaxRange / maxRGB, 1.);

              D            = clamp(floor(D) / 255.0, 0., 1.);

              // vec3 rgb = color.rgb * (D * (255.0 / rgbdMaxRange));

              vec3 rgb = color.rgb * D;

          

              // Helps with png quantization.

              rgb = toGammaSpace(rgb);

          

              return vec4(clamp(rgb, 0., 1.), D); 

          }

          

          vec3 fromRGBD(vec4 rgbd) {

              // Helps with png quantization.

This file has been truncated. show original

Nope but would be great if you could provide a repro of it not working ?

joie · February 13, 2023, 12:56pm

Nevermind, I managed to make it work.
I wonder, though, if the resulting PNG can be converted to JPG as I don’t know if JPG supports RGBD formats. Because our converted PNG is like 20mb in size, and that’s pretty much.

Evgeni_Popov · February 13, 2023, 1:37pm

No, jpg can’t support RGBD because it does not support an alpha channel (and also because it is a lossy format).

joie · February 14, 2023, 6:52am

Unfortunately, my code guy says 20mb for a RGBD lightmap is way too much for downloading, so will stick to regular RGB format and JPG lossless.

sebavan · February 14, 2023, 4:42pm

Not sure why it is 20Mb as this would even be big for a full HDR file.

What size is it ?

joie · February 15, 2023, 4:49am

The HDR file is like 30mb and the resulting PNG RGBD is ~20mb. Should it be more or less?

sebavan · February 15, 2023, 8:03pm

sorry I meant resolution of the png ?

joie · February 16, 2023, 1:31pm

It is 4k

sebavan · February 16, 2023, 10:26pm

yup pretty large and if there is a huge dynamicity the compression might not help much

joie · February 17, 2023, 5:04am

Well, I’m completely new to lightmap generation (I come from offline rendering, so no need for them at all), but I thought ONE lightmap for everything in the scene would be appropriate, that’s why I use one 4k file for it.

Sarrus4x4 · February 20, 2023, 7:50am

@sebavan Please excuse my late response. I looked at the scene again and came to the conclusion that the effect I was experiencing has to originate in the lightmaps that are used.

The original scene:

The scene with a Lightmap:

It seemed to me as if there was a bumpmap being used or something similar that changes the actual geometry of the mesh, but it is just the effects of the Lightmap tricking my brain

Moriy · February 20, 2023, 8:59am

You should create a new topic to ask your question and link this page. Forum seems don’t notice reply or @someone if topic you visit is solved.

sebavan · February 20, 2023, 11:25am

@joie ios only supports max 2k by 2k textures

@Sarrus4x4 it looks more like you did not set an environment texture ???

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