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Author Topic:  Things disappear as you get closer sometimes?  (Read 259 times)

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Offline recursiveid

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Things disappear as you get closer sometimes?
« on: April 24, 2021, 02:32:42 AM »
I've noticed sometimes there will be smaller details in a fractal, sometimes maybe something very thin, and when you zoom in a little closer it fades away with a kind of dotted thing going on. Probably zoomed in a lot too.  Is there some way to prevent this? I thought maybe it was the DE stop, but I haven't had luck with changing it. I can paste in an example if I can dig one up where it happened.  Was just thinking about it. Thanks!

Linkback: https://fractalforums.org/index.php?topic=4172.0

Offline Adam Majewski

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Re: Things disappear as you get closer sometimes?
« Reply #1 on: April 24, 2021, 10:05:41 AM »
intresting question. "Help others reproduce the problem" -https://stackoverflow.com/help/minimal-reproducible-example

Offline youhn

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Re: Things disappear as you get closer sometimes?
« Reply #2 on: April 24, 2021, 08:55:08 PM »
It's just how reality works, if you look very closely at one spot at a single moment there appears to be nothing. Maths and computing is a subgroup of reality.

Just add some (small) perturbations and look at the same spot, then something will appear after a number of iterations.

Please keep in mind that any single spot is also defined by it's surroundings, and too much focus on one spot blurs everything else.

Other tips that might help:
- More iterations
- Decrease the near-cutoff setting (view distance)
- Decrease the distance estimation step distance
- Use smaller angle of view
- Higher resolution
- Use a fixed detail size, tune to specific needs
- Don't get so close
- Use monte carlo ray tracing
- A combination of the above
- Scan through the software documentation
- Try some semi random changes to any other parameters that might look applicable

Offline Sabine62

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Re: Things disappear as you get closer sometimes?
« Reply #3 on: April 25, 2021, 05:09:14 PM »
Do paste an example, if you please?  ^-^
To thine own self be true

Offline recursiveid

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Re: Things disappear as you get closer sometimes?
« Reply #4 on: April 25, 2021, 05:57:07 PM »
Thanks for the great responses! Yeah I've been trying to recreate this for a good example... I'll post one as soon as I can find it. I also just think that there's not much you can do when this happens - certain formulas and combinations just seem to do it more than others I think...

Offline recursiveid

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Re: Things disappear as you get closer sometimes?
« Reply #5 on: May 03, 2021, 05:28:05 PM »



Mandelbulb3Dv18{
g.....m...Uk/...w....26....VyyhjHnm1.nJA6pPEHc5EqQ4tRj2BlzXJK2JvACG5.vgDbNzkWu.k
................................NioIgGlD9/2........Y./..................y.2...wD
...Uz6...A.0..../MU0/......X4...51....E4.....I2XjcsffakD/.......29gc//.........U
y.UaNadD12../..........wz.................................U0.....y1...sD...../..
.z1...kDtGwvgkCLsvfECN8rXIFty2Oy/t.4tLkjEXDVJITfdv16PCgLvq90zQZkumI6/AhD0svVDQYe
3wXyBeZfqWLsy0OwELoxRcjjU.....2C..............sD.6....sD..G.....................
.............oAnAt1...sD....zw1...................................k6H01FK....k1.
.....83iyz1.......kz.wzzz1EH..6.P....61....C....m....c3....F....6/...I1.....SF52
...U.ydelyjeYFnz....zLjps16.nc..zzzz............6............0........k.WxTyYL5.
.sM93P58iz9.MmnWK2zwz0........../EU0.wzzz1...........s/...................E.2c..
zzzz.............0...................2./8.kzzzD............8....................
/EU0.wzzz1...................................w6TT0.bHGe7qUVPcC7.odcUoACAguvP.wMY
Ban07RKVu0kA.Vp69.KRcB8.uKfma.UNmqtJ.w7bFO0Lft4eH0.R886Bs0LRcB8.uKfmaEVRbJci.A1E
MBW7wx6TT0.bHGe7...OjhOJzz/RERIdyz1OPJsdxzJTGioU................................
E....AU.V2E.....I....k....EEh3aSdtqN0x4Sm.UQ..........................k/.MU/4...
.ok.1................/........yD........kz1.....................................
...sz..............................wz...........................................
.....................2.....3....0....wJEh3aSdtqN0x4S............................
.Q.............................E........Uz1.....................................
................................................................................
................................/....E/...U.....T3IPVdLOiRaEjV5.................
............5.............................2........sz...........................
................................................................................
............................................}
{Titel: View of keyframe #1}


Ok zoom into that structure right there and you'll see some of the objects on the front side disappear... It happens in a lot of places around this fractal, the narrow bands and the "surface" sometimes...  Thanks!

Offline Sabine62

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Re: Things disappear as you get closer sometimes?
« Reply #6 on: May 08, 2021, 02:12:46 AM »
Thanks for the parameters!

I am still not quite sure what you mean  with the disappearing shapes. It sounds a bit like oddities due to poor render quality. Do the structures disappear/change when zooming of moving?

The narrow bands: try and uncheck Normals on DE on the Calculation-tab, but Do check Raystep Sub DE Stop.

Your Far Plane value (navigation window) is Very high and that will lead to problems and slow renders. Try to keep it at something between 1 and 100 if possible. This means you will have to move closer towards your structure (which means you will be able to zoom deeper without problems). I changed your Far Plane to something 10 and could zoom without loss to 5.756E10 (that's where I stopped ;) )

Attached image below

Code: [Select]
Mandelbulb3Dv18{
g.....Y/...V1...w....I6...UFUiLwZYy1.TW.h3T7dz.kv70p2jOYqz1C5L3YLwK5.zjPt3T7dz.k
.................................n4EOmXne62........Y./..................y.2...wD
...Uz6...AE4.....MU0/.....EH2...v4....E4.....cc5IY5kLcFD/.......29g60/..........
z.UaNadD12..0..........wz.................................U0.....y1...sD...../..
.z1...kDAdlnNjrk6ovmfQcGYrKxwo9idg/aJNFjYe5XIyU4unXvKiRZWLG4xopgTsV6FBCDo3W.FhL/
Ko1XtCLW17QwwCgJAgIu9eEjU.....2G/.............sD.6....sD..G.....................
.............oAnAt1...sD....zw1...................................k6H01Fj....k1.
.....Ksulz1.......kz.wzzz1EH..6.P....61....C....m....c3....F....6/...I1.....SF52
...U.ydelyjeYFnz....zLjps16.nc..zzzz............6............0........k.WxTyYL5.
.sM93P58iz9.MmnWK2zwz0........../EU0.wzzz1...........s/...................E.2c..
zzzz.............0...................2./8.kzzzD............8....................
/EU0.wzzz1...................................w6TT0.bHGe7qUVPcC7.odcUoACAguvP.wMY
Ban07RKVu0kA.Vp69.KRcB8.uKfma.UNmqtJ.w7bFO0Lft4eH0.R886Bs0LRcB8.uKfmaEVRbJci.A1E
MBW7wx6TT0.bHGe7...OjhOJzz/RERIdyz1OPJsdxzJTGioU................................
E....AU.V2E.....I....k....EEh3aSdtqN0x4Sm.UQ..........................k/.MU/4...
.ok.1................/........yD........kz1.....................................
...sz..............................wz...........................................
.....................2.....3....0....wJEh3aSdtqN0x4S............................
.Q.............................E........Uz1.....................................
................................................................................
................................/....E/...U.....T3IPVdLOiRaEjV5.................
............5.............................2........sz...........................
................................................................................
............................................}
{Titel: zoom}

One thing that does not work well here is the fog which generates white patches in the centre of the image. Set the fog to 0 and they are gone...
Maybe other settings will work better for fog and/or other colours

Another thing: AmazingBox2 is somewhat tricky to get right because of the inversion of C (which leads to fuzzy edges here and there if you are not careful with the values) That's why the upper part of the structure in the original seems to come apart, for instance.
I set InvCx to 0 (basically cancelling the inversion) for AmazingBox2 and you will notice how much 'cleaner' the structures look.

Attached image below

Code: [Select]
Mandelbulb3Dv18{
g.....Y/...V1...w....I6....vKIeoxTj2.5vgMAV0A7zjQAK./Db4vzXxgv.15BO5.TXqqPcDD1/k
................................MSqeXBACP.2........Y./..................y.2...wD
...Uz6...Ak2.....MU0/.....Ez1...51....E4.....M0tSj8dlamD/.......29g60/..........
z.UaNadD12..0..........wz.................................U0.....y1...sD...../..
.z1...kDbVtpRCdMcwvLy6BO6cF3zUOj04MAyLnjVgf8yeygNwX/U6oFtBACzMXsX3aW3AkDPSk9ssof
pwnr1PDg2nL2zW89Doi/YcmjU.....YS..............sD.6....sD..G.....................
.............oAnAt1...sD....zw1...................................k6H01FK....k1.
.....Ksulz1.......kz.wzzz1EH..6.P....61....C....m....c3....F....6/...I1.....SF52
...U.ydelyjeYFnz....zLjps16.nc..zzzz............6............0........k.WxTyYL5.
.sM93P58iz9.MmnWK2zwz0........../EU0.wzzz1...........s/...................E.2c..
zzzz.............0...................2./8.kzzzD............8....................
/EU0.wzzz1...................................w6TT0.bHGe7qUVPcC7.odcUoACAguvP.wMY
Ban07RKVu0kA.Vp69.KRcB8.uKfma.UNmqtJ.w7bFO0Lft4eH0.R886Bs0LRcB8.uKfmaEVRbJci.A1E
MBW7wx6TT0.bHGe7...OjhOJzz/RERIdyz1OPJsdxzJTGioU................................
E....AU.V2E.....I....k....EEh3aSdtqN0x4Sm.UQ..........................k/.MU/4...
.ok.1................/........yD........kz1.....................................
...................................wz...........................................
.....................2.....3....0....wJEh3aSdtqN0x4S............................
.Q.............................E........Uz1.....................................
................................................................................
................................/....E/...U.....T3IPVdLOiRaEjV5.................
............5.............................2........sz...........................
................................................................................
............................................}
{Titel: InvCx is 0}

Also some tips for good render quality:
- render at least twice as big and save with Viewing 1:2 for Anti-Aliassing
- lower Raystep Multiplier and Stepwidth Limiter
- increase Stepcount and Smooth normals

Many problems 'magically' disappear with good render quality ;)

Ok, I hope this helps!
If not, please tell me what I have missed?



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