Luxcore vs real Photo

[Sharlybg]

The gimp tag is just a conversion from Raw Arw format to jpg nothing more raw and jpg are equal.

And yes i don't think it is related to bump.
Also at the begining i though about camera color sensitivity
But after looking many camera and diffrrent colored ball inside color bleeding look way stronger.

Cycles also show same behaviour.

What should i do to enable bidirvm in luxcore just for curiosity. Also when enable how do i notice it is not simple bidir.

[CodeHD]

For BidirVM, this should still apply:

viewtopic.php?f=4&t=1835

[Sharlybg]

For BidirVM, this should still apply:

viewtopic.php?f=4&t=1835

You're awesome !

[daros]

Hi, i'm David, the guy who is sampling this real materials. Sharlybg is helping me with the lux settings. All photos have been taken under exactly the same light conditions, camera settings, color correction white balance and so on. Every kind of automatic white blance and adjustment of the camera has been disabled. Raw files have been processed in Rawtherapee and even here all automatic adjustments have been disabled, even the highlight reconstruction. White balance has been calibrated on to the white box+white ball. All other photos use exactly the same white balance calibration, light color and so on.
The material on the ball is exactly the same lime as on the box. The different roughness depends only by the mechanical application of the lime.

[daros]

And i have forgotten to say that the 3dmodel used by sharlybg matches to the mm the real model. We went carefully through every detail. The box is approximately 82cm deep, 40cm high and 60 wide and it was built specifically for sampling materials.

[Dade]

And how exactly have you measured the properties of the white material ?

[daros]

i use a minolta colorimeter

[daros]

But since we have only two variables, material and light, it is not even so important. Color bleeding would behave proportionally in the same way even if the white material is 5% warmer or colder, or if light is 5% warmer or colder. As soon as the sphere has a color, color bleeding and light absorption start to play a key role in the scene. Today i send you a tests done with mitsuba. Let's see.

[Sharlybg]

Can this play a role in the final look of the image as we are dealing with rough material :

[CodeHD]

No you don't need to worry about roughness here. You can see a very clear reflection of the scene in the copper sphere, which means it is not rough. (Corresponding to the left shader ball in that picture, where you have no difference).

Rather the opposite, I have noticed that the LuxCore image showsa difference in this regard. Note the lower contrast of the black line/dot seen on the sphere.
Anyways, since it is a white box there is much diffuse rescatter so I expect little impact on the background color (and in any case there should be more red on the back wall, not less).

I don't have time today to test any more, but I would still be interested to know what type of light source you used (Incandescent, fluorescent, white LED, RGB LED set to white ?). The reflectance spectrum of copper has a relatively steep drop, so in combination with fluorescent or RGB LED there could the spectral effects not resolved by LuxCore.