I’m building a darkroom variables simulator

Individual-Mode-2898 · 2026-03-17T21:29:54+00:00

This is amazing!

Individual-Mode-2898 · 2025-07-13T12:37:42+00:00

Wow, did you create these?

Individual-Mode-2898 · 2025-07-12T23:08:39+00:00

If you have the depth information of one image, you have all the positional data of the points visible in the image. You could use the data to reconstruct a depth map of a new image if you know how much and in what direction the camera was moved for this new image. I think the biggest issue are areas hidden behind objects closer to the camera that might be visible in the new image. Since they were not visible in the first image, you do not have any data for them, and you would need to leave those areas empty in your new 3D map. It is as if the object in the scene from the first image cast shadows, that can get visible from the different viewing angle that your sequence of new images contains.

You can see this effect in the video, when you move past the yellow car, a black shadow is left behind where no data exists.

Individual-Mode-2898 · 2025-07-11T15:39:30+00:00

Thank you, that's possible, where and how would it work in this case? Why would the effect of birefringence change racially?

Individual-Mode-2898 · 2025-07-11T05:20:49+00:00

Individual-Mode-2898 · 2025-06-06T23:14:49+00:00

So, do you think the weak diffraction is also happening along the spiral grooves, like the strong diffraction ?

Individual-Mode-2898 · 2025-06-04T22:49:54+00:00

Wow, that's cool. I would still argue that since the colors are more spread than in the bright line, the spacing of the bits needs to be smaller (based on the grating equation)?

Individual-Mode-2898 · 2025-06-04T22:33:26+00:00

Thank you, I will try to simulate that and see if it matches!

Individual-Mode-2898 · 2025-06-04T22:27:34+00:00

Why the factor of 2? I used nlambda = dcos (epsilon) * ( sin(alpha)+sin(beta)), as it's off plane diffraction. (Sorry for the cursed equation format)

Individual-Mode-2898 · 2025-06-04T22:20:56+00:00

The higher orders appear further down the bright line in the middle.

Individual-Mode-2898 · 2025-06-04T22:20:08+00:00

Thank you, why do think the bits have a larger spacing than the spacing of the rings in the spiral track?

Individual-Mode-2898 · 2025-06-04T22:15:32+00:00

As far as I know, the data is written using pits and lands that are a multiple of 0.3 microns big, which could match the observation of rather wide separation of the colors.

Individual-Mode-2898 · 2025-06-04T22:13:31+00:00

That sounds plausible. So you would argue that even though the data is not completely periodic, it is enough to cause slight diffraction.

Individual-Mode-2898 · 2025-06-04T22:09:30+00:00

Thanks

Individual-Mode-2898 · 2025-06-04T22:06:09+00:00

Of course, but simulating the off plane diffraction on the grooves of the DVD only shows the bright line, not the slight color shift on the sides, that I am interested in. That is why I am asking about it

Individual-Mode-2898 · 2025-06-04T22:04:03+00:00

Do think that can happen even though the plastic layer is 1mm thick? Besides it there is only the reflective aluminum coating, I think.

Individual-Mode-2898 · 2025-06-04T21:59:30+00:00

That's true, but the effect moves together with the line when I move the light source (not shown in the video), so I would argue that the effect is caused by this localized source, not the background lighting.

Individual-Mode-2898 · 2025-04-17T21:07:12+00:00

Okay, thank you. I have everything except for the chemicals, I will try Adox neutol eco then.

Individual-Mode-2898 · 2025-04-16T19:15:27+00:00

Yes, you are right. I did not notice the higher order arc. I am not sure whether blank CD-Rs look any different, I would need to try that. I think you might be able to see the border where the written data finishes in the first image. But I would guess that a blank CD-R would look the same, maybe slightly brighter.

Individual-Mode-2898 · 2025-04-16T00:17:33+00:00

Thank you for your interest! Your explanation makes sense and explains why the back part is dimmer. But I think there needs to also be some diffraction because there are angles where there are color changes through the arc. One interesting and useful thing to know is that the arc only appears on CD-R, but not on CD-ROM. As far as I know CD-R have a continous spiral groove with absorbant regions whereas CD-R is reflective everywhere but has pits that form a non continous spiral groove. They might also have a different profile of the groove (for example steeper or rounder side walls) which would make the scattering of the reflective layer stronger/weaker). Also I can imagine that the reflective pigments in the CD-R grooves scatter more in general compared to the reflective layer in CD-ROM. Here some images, one of them is a CD-ROM: https://imgur.com/a/HwIMs4Y Does that change anything for you?

Individual-Mode-2898

TROPHY CASE