Minitutorial about polishing cut fractals (en)

3 min read

Deviation Actions

Jakeukalane's avatar
By Jakeukalane

Sometimes we find that, in an already rendered fractal, there is an interference between the fractals and a plane, resulting in a fractal that seems to have been cut (fig. 1). There are at least three ways to avoid this:

Interference by Jakeukalane Fig. 1

  • A. Activating "In and Outside" rendering. This is what I did when I didn't know much about MB3D. It is very slow. Can easily duplicate the time of a fractal because have to render both sides. The description itself of the inside mode is "slow raymarching on the inside with maximum iterations".

Pantallazo del 2016-06-14 14:47:15b by JakeukalaneFig. 2



  • B. Avoiding the "cut surfaces" by walking in or out (remember to tick first, "Fixed zoom and steps"(!), or changing iterations, etc. In resume, using 3D Navi. This is most of the times the better solution.

  • C. We can re-calculate those parts of the image.

And this what I want to explain in this simple tutorial. Sometimes you can't avoid those "cut surfaces" by using 3D navi, or it is unconfortable to do (you already have everything done etc), or even you realize when you see the image rendered (that can happen often when the 3D navi has a very foggy preview).

It is preferible to do this before calculating lights and this kind of things. If not, is preferible to save your m3i before recalculating the image because it changes the lights (I usually mix the images in GIMP, one with good lights, one without cut surfaces). [For further info, see this comment of GraphicLia].

  • 0. We have already rendered the image we want, but there are several "cut surfaces".
  • 1. So, we go to the Formula window and we select  "In and outside" (Fig. 2).
  • 2. We go to the "Post processing window" and we select "Recalculate selection" and "Enable". If we already have calculated lights we press "Don't change AmbSh+dFog" although in my experience sometimes the lights/colours change anyway so that's why doing this before aplying shadows.
Pantallazo del 2016-06-14 15:06:42 by Jakeukalane Fig. 3.

  • 3. Then we go to our image and select the part we want to recalculate and press "Calculate".  Is better to not make enormous selecctions and if we have a point in other part of the image, do the calculation separatedly.

Pantallazo del 2016-06-14 15:09:21 by Jakeukalane Fig. 4

  • 4. After doing two calculations, this is the final image :D
Interference2 by Jakeukalane


This recalculate tool can be used in multiple situations like very grainy images too or artifacts.

Published:
© 2016 - 2021 Jakeukalane
Comments30
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BGai's avatar
Thanks Alberto! A problem I am very familiar with but had no idea what to do about it.
Jakeukalane's avatar
nice, glad to be helpful :) anyway the better thing to deal with it is with the camera :)
BGai's avatar
Haven't had a lot of success with MB3D lately so have stopped using it for a while. Need to get some motivation back!
GBLXVIII's avatar
Fantastic. I've seen it now (I'm asleep). Thank tou for sharing, I'll try it soon.
Jakeukalane's avatar
well, I am bit surprised for the amount of people that seen this useful :D hehe
GBLXVIII's avatar
Aha, don't underestimate yourself. It's a very well done tutorial about a an unusual feature, and I've learned that everything explained about Mandelbulb is very well accepted!! :D (Big Grin) 
Jakeukalane's avatar
:D I should do an integral one then.
ChasMandala's avatar
Thanks so much for sharing this information with us, Alberto - I hope to put this to use for my future abstracts!  :handshake:
Jakeukalane's avatar
Nice :) I want also to make spanish tutorial form the very beginning. Maybe with that I could encourage my friend Avengium and my Nefertaery2007 :heart: to use the program :D
ChasMandala's avatar
Excellent, my friend - I wish you luck, and take care!  :)
Eddie-65's avatar
Thanks very much for this, very helpful!
marijeberting's avatar
Thanks for sharing Alberto
Jakeukalane's avatar
My pleasure. I want to translate much of the mandelbulb tutorials to spanish so this is a kind of training
Sabine62's avatar
Thank you for all that, Alberto! :hug:

I never really have the patience to re-render parts FOREVER WAITING  , but maybe I should ;) I also often end up the few times I use it with a change in colour tones/light, annoying really. But maybe I should try more often;) BTW usually I set my Inside colour to something horrible like flaming red or bright purple so I cannot miss the cuts on the small renders I always do Before rendering big;)

I have one tip about the above though: Under B. Zooming in and out will not help avoid cuts, you just move away from them. What really heals cuts (as far as possible, if the area is terribly tight packed cuts are very hard to avoid, then you have the option of Looking while finding a viewpoint that is a bit different) is Walking in and out (mouse or W and S on keyboard) :)
Jakeukalane's avatar
yes, that's what I was refering with "changing perspective" but that phrase is the correct one. I will correct in the journal.

I didn't know that you can change colour of Inside rendering... :D

Yep, I also noted the change of colour, maybe the comment of GraphicLia can help you, or doing before adding lilghst...
Sabine62's avatar
Thank you, Alberto!
Read Ingrids comment, but I always rerun Ambients (and Hard Shadows if I used them) after... Still often strange colours/light.. Oh well;) More experimenting is needed!! :nod: :)

Ohh... and walking does not necessary change perspective a lot: You can Walk out and then Zoom back in and land at about the same spot ;)

The colour(s) for the Cuts are the Inside colours. Have a look at he lighting tab for the red Cuts colour. You can click on that and change it, just like the Outside colours

Mandelbulb3Dv18{
g....U5...UK....w....2...............1.......s1E................................
........................................kz1........A./..................y.2...wD
...Uz6....E/..../M.0/.....Eg....b.....E3.....omEQgisq6tD/..........m.dkpXm1....U
y.....kD12../..........wz.................................U0.....y1...sD...../..
.z1...sDYsAIxzzzjz1..........WAbUdisqcljRRxgCKosEwnYRydIKa5uzwPN9SaPRGyDFHQlSHA1
Iw1iNMIOip7tzqF/G0ZZtVyDU.....2...............sD.6....sD..G.....................
.............oAnAt1...sD....z...........................................5....k1.
.....Ksulz1.......kz.AGCz..U..6.P....E1...EB....Q/...Y3....F....6/...I1.....SF52
...U.yoPxBGEGdJCXYnDzcfqY16.2c..zTTr..UkKZMxkayD6EdGkxmWcz1...........k.8.kXWF1.
.sM93P58iz9.MmnWK2zwz0...........EU0..G92/...........s/...................E.2c..
zzzz.............0...................2./8.kzzzD............8....................
/EU0.wzzz1...................................c6Uc/EBpIHB3fUWhl2..1Ak.LQ3gK8X.IHB
pInwT6sQL/.k.1AkD0nW846.pIHBpsXCvV4E.wzzzzDVERsUu/EBpIHB/xJX7S6.pIHBpEjO5uLO..Ak
.1Qcs3dUU/.k.1Ak..kz..EHeemz..EHIJpz..EHwyrz..EH................................
E....2..F2E..........6....EGiFLNbJaQU.pPrJaQ.........................c..........
...................6./........zj................................................
................................................................................
........................}
Jakeukalane's avatar
Corrected :D

Well, that is why I recommend to save all the m3i before doing this :)

:o I didn't see that button before... it is like I am blind or something...

Thank you :)
Sabine62's avatar
Trust me, my friend, I discover new things in MB3D all the time as well! Maybe that is (partly) what makes it so great! :) We live and learn :nod:
Thank you! :hug:
MarysFractals's avatar
Great tutorial. I always trash good images because I have cuts in them and can't figure out a way to get rid of them.
Jakeukalane's avatar
Thank you :) Good luck with this. Be careful with lights :)
AguraNata's avatar
Thank you for this post :-)
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