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Author Topic: Noob question - Fractals seem to be cut by a flat plane  (Read 589 times)
Description: Fractals seem to be cut by a flat plane when you get close to them
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TheCapedMadman
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« on: July 29, 2017, 11:15:03 PM »

I've been using MB3D for a while but I don't play with it as much as I'd like to. I've noticed right from the start that I often get results that look like the fractal is being cut by a piece of glass that's in front of the camera (so to speak). See example. I've read in some tutorials that this is because the camera is inside the fractal but I'm not sure that's correct because I've seen some animations where the camera seems to pass very close to the fractal surface and the fractal does not disappear. I've tried zooming in and out, changing the far plane, FOV, and every other setting related to the camera and nothing changes.

Is there a way to get closer to the fractal surface without having the surface disappear?

https://1drv.ms/i/s!AipZfHXaoLuv7BgSEzYwVU3a5Np5
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DedXP
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« Reply #1 on: July 30, 2017, 02:56:07 AM »

Try reducing the Z start value in the Position rollout in main window. It's just the camera near plane clipping. I think the default is -2, but if you are inside the fractal, that may not be enough. Also, checking the 'fixed zoom and steps' box and zooming in and out can solve it. If you are inside the fractal, I find that turning on inside and outside rendering (bottom right rollout on Formula window) can allow you to navigate outside the fractal.
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Sabine
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« Reply #2 on: July 30, 2017, 11:25:28 AM »

There are two things that affect this in mb3d: the way you navigate (walking versus zooming) and which of the modes you use (inside, outside, in- and outside)
Have written two little tutorials some time ago:

http://sabine62.deviantart.com/art/MB3D-Navigating-3D-for-beginners-575764485
http://sabine62.deviantart.com/art/Mandelbulb3D-In-and-outside-render-542686928

Hope these help smiley
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sabine62.deviantart.com
TheCapedMadman
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« Reply #3 on: July 31, 2017, 09:37:08 PM »

Thanks to both of you. I knew about the walking vs zooming thing but didn't know about outside-inside feature. I tried it and at first I thought it had solved the problem but it really just took away the capping plane so it's not really what I was after.

Zooming in does take care of the clipping because it essentially moves you past the clipping point but zooming introduces a couple of other problems. The first is that it reduces the "wrap around" feeling that you get with a wider view. I know you can increase the zoom and then increase the field of view but when you do that you get a "tiny planet" look which is the opposite of what I want. Extreme zooming also seems to screw up the lighting (mainly the fog settings) during an animation. This is quite likely something I'm doing wrong but if I have a high zoom setting and I create two keyframes as I walk toward an object, the lighting will slowly become very high contrast until the image is almost black and white by the time I've almost reached the second keyframe. If I pause and stop the animation and then re-render the last rendered frame manually, the lighting will return to normal. The lighting usually jumps back to normal when the animation reaches the second keyframe.

I've done a bit more playing around and at the moment it seems like the problem may be that some formulas allow you to get close to the surface and some don't. That seems odd but in this image (with a very low zoom (35) and a very wide FOV (170)) I can get very close to the circles (rings) without them clipping but I can't get close to the amazingbox part of the formula at all. The tendrils on the left and right are actually rings but the wide FOV is distorting them greatly. This is the wrap around feeling that I mentioned before.

https://1drv.ms/i/s!AipZfHXaoLuv8B1Cugnvw4JQwP1Y
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Sabine
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« Reply #4 on: August 01, 2017, 12:18:52 AM »

Hello again!

I virtually never have any trouble getting closer to a certain area provided the far plane is adjusted, except for very rare cases. In the example you gave in your first post, walking out and then zooming back in does the trick. In your second example I cannot really tell you what the problem is without the parameters. If you are ok to share them (or similar ones), please do! If not, you should be able to walk closer and zoom out. Since your field of view-setting gives a rather warped  image you will probably end up with a slightly different image though...
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sabine62.deviantart.com
TheCapedMadman
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« Reply #5 on: August 03, 2017, 02:14:09 AM »

You are right that walking out and then zooming back in does solve the problem but like I said before, it does change the look of the image, mainly fog depth (for me anyway). There is no clipping in these three images but the first one will clip if I walk forward. The second one is walking out and zooming in (with no change to the lighting settings) so that I no longer get the clipping when I walk forward. And in the third one (using the zooming and walking settings from the second image) I tried to get the settings as close to the first as I could. The DOF and Ambient Shadow calculations obviously change as well so I guess I'll just have to learn to make sure nothing is clipping in the animation before I start setting up the lights, DOF, etc.

https://1drv.ms/i/s!AipZfHXaoLuv8DQqJu_NK62iMPvU
https://1drv.ms/i/s!AipZfHXaoLuv8DPNRMYcxqxZxK4m
https://1drv.ms/i/s!AipZfHXaoLuv8DUlXMGYwX-Eu18G

I played around with the other file a bit and found that the zero 'Z' point is ahead of the camera. In this screen shot the brown bit in the middle of the screen is being clipped. If you look at the "Z1 Sharp" point in the Post Processing flyout you'll see it's at zero. I clicked the "Get Z1" button and then clicked on the clipped brown part of the image.

https://1drv.ms/i/s!AipZfHXaoLuv8DJOrXCBP9POR5ur

In this next screen shot I've zoomed in, changed the FOV slightly, and Slid down a bit to keep the object in view, but I haven't walked forward or backward. The object obviously got larger but it's still at Z position zero and still a ways in front of the camera. If the camera was at zero then the whole image should be brown (in my thinking).  

https://1drv.ms/i/s!AipZfHXaoLuv8DAiMlHIp6xE2NYQ

So if the camera is a giant sheet of glass perpendicular to the Z plane and everything on the viewer's side of the sheet of glass is clipped and zooming moves your viewpoint forward and backward on the Z plane so that you are either in front of or behind the sheet of glass... what zoom value places you at the sheet of glass? Or does the value vary with the distance you have moved into the fractal? Or in other words, am I going to have to increase the zoom value the further I move into the fractal to prevent further clipping?

This is the image data if you want to play with it -

Mandelbulb3Dv18{
g....EF/..kq0...u1...22...EF5qTuHvQ/.5n5wF872H.kgCPsjRIY/x9P7jEaY0LQzEQ0PTXG4L.k
................................yKlMJDBW902........Y.71................U//2...uD
...c.7...wkK..../.U0/...........B2....kf.....MAqYfra1xfD/.....sD...m/dkpXm1....U
z2UaNaVD12../..........wz.................................U0.....y1...sD...../..
.z1...kD5J2XsH33xuvVHdl4Hy1ayC6SHJMU.CeDzKjlaHMP.uv05gJoO0qhyKzvEanFcGfj/ndA8.yZ
auHurZAmnexgyWIKMqqSMJfDU...U2oe.........2....8E.2....sD36H.0...................
.............oAnAt1...6E....z.........................................0EU....k1.
.....4iSoz1.....yzzz.wzzz1.G.M5.X0...w0...kC.........kA...U3....7/...Aom....G2r1
Sc3U.W1KEyzlciszsU3YzTAe906MqEVyzzzz............6.........k..eRQv4Q/.Ha3Qdzzby2.
.Ecy8dL/Zx1.JAxyiC0Sz.kZQYBy9L.k/JF10wDU....RbdhssszzsVrOA.Km..E/MOz6bgm3.QF.AKy
zH78..E6gy.r1PrDF9J128INEx1.0BrLE.Q/.5Y/8....yD............8..........EMEGvyZJ.k
/FU0.wzzz1...................................E6V20.xoHD.R1/V2G6.oHDx.ci52G6V.EDx
o1UjgE6V20.xoHD.qb1V2G6.oHDx.wqF2G6V.EDxo1EdJF6V20.xoHD.PA4V2G6.oHDx.gJQ2G6V.EDx
o1kzzF6V20.xoHD...kbTy7.eembTy7.CJpbTy7.mzrbTy7.................................
E....6E.F2.1....2....A....EEh3aSdtqNU6oPs/UQ..........................k/9.......
..........EaNaNaNSvwzUNaNaNaNKwDnAnAnAnIoz1.....................................
................................................................................
.....................M.....3....9....oINiRKNmVISkJaQ............................
.............6................/E..........2........wz.........yD........cz9.....
................b210gmVKIzXyyd4joB7ezoAnAnAnAnyD........kz1.....................
................................}
{Titel: Keyframe #1}
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Sabine
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« Reply #6 on: August 05, 2017, 03:44:51 PM »

Thank you very much for your elaborate reply and the examples!

In this next screen shot I've zoomed in, changed the FOV slightly, and Slid down a bit to keep the object in view, but I haven't walked forward or backward. The object obviously got larger but it's still at Z position zero and still a ways in front of the camera. If the camera was at zero then the whole image should be brown (in my thinking).  

From what I can distil from the limited documentation coming with mb3d and my own experiences I think it must be something like this:
The camera is always at z=0 (as when getting a position for dof you can never get a negative one), seems we are always in camera-mode (vs. object-mode which you might know from 3D-programs). As soon as you walk in/out the z=0 'walks' with you. If your image shows cuts (brown in your case) your z=0 always lies at that point. Whether your whole image is a cut does depend on your object (the more solid your object the bigger the chance that you end up with a full screen cut, try to walk into boxIFS, for instance, a fully solid object, and then do the same with f.i. aboxmodkali which is a rather more "open" structure), where you are relative to it (at the edge or inside the object) and your zoom level.

So if the camera is a giant sheet of glass perpendicular to the Z plane and everything on the viewer's side of the sheet of glass is clipped and zooming moves your viewpoint forward and backward on the Z plane so that you are either in front of or behind the sheet of glass... what zoom value places you at the sheet of glass? Or does the value vary with the distance you have moved into the fractal? Or in other words, am I going to have to increase the zoom value the further I move into the fractal to prevent further clipping?


As I said above: the camera is always placed directly at your sheet of glass smiley Moving the camera to the place to where you not yet have cuts is the only option and after that, zoom and changing the farplane are your friends here.

Thank you for the parameters. I did mean the 'difficult ones' with the wrap-around feel, really wink But I what I can say is: as soon as you have to change position, light, fog etc may and more often than not Will change, especially when you work with high FOVy's.

From what you wrote I gather you ask your questions because you are going to create an animation. You might want to have a look at these options that might make things easier in certain situations:

The lights of your scene: check them all as being "Rel. to object" on the Lighting tab (all except Maybe the one used for VL if that is a positional light) Sometimes this is a big help.
In the navi window: click the "Min. distance"-button and uncheck "Fixed zoom and steps". This way you set the animation maker to try keep a minimum distance when getting a path between keyframes. This should reduce the chance for cutting.

Sadly, as with almost all settings within mb3d, what works for one scene, will probably not be working for the next. Oh well, keeps us from the streets;)
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sabine62.deviantart.com
TheCapedMadman
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« Reply #7 on: August 07, 2017, 04:23:44 AM »

I am creating animations...   smiley

This was the first (but not my first) - <a href="http://www.youtube.com/v/6MhL06WIq5w&rel=1&fs=1&hd=1" target="_blank">http://www.youtube.com/v/6MhL06WIq5w&rel=1&fs=1&hd=1</a> - and I want to redo it because I didn't know about the DEAO setting in the Ambient Shadows at that point. I was unhappy with the way the shadows were disappearing so I was going to give up on that one but I'll come back to it after I'm finished the new one. There are only a couple of problems with cutting on this one and I will probably just fix them by choosing a different path for the camera rather than changing the zoom setting.

This is the latest - <a href="http://www.youtube.com/v/asvxsKdGNH8&rel=1&fs=1&hd=1" target="_blank">http://www.youtube.com/v/asvxsKdGNH8&rel=1&fs=1&hd=1</a> - and it's just part of a longer, larger render that I'm currently doing. I've done a couple of preview and low resolution renders with this one to make sure that I'm not cutting into the fractal at any point. I've changed the lens to rectilinear though to reduce distortion. This one probably won't be finished for a couple of months though so I might have forgotten all about this by then.  lol

It's funny how I thought I was doing something new for both of these animations but as time went by I've found that a few others have already done something similar.
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Sabine
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« Reply #8 on: August 23, 2017, 09:54:50 AM »

Sorry for the late reply, life doesn't allow me much playtime lately;)

Beautiful videos, be sure to post an update when they are finished!

And yes, forms and structures are rediscovered all the time! No harm there, I am always glad when someone can show me a fractal in a new light. See it as something like flowers or the human body... They have been painted millions of times over the ages, but still can fascinate by the unique way the artist depicts them:)
On the other hand, there are loads of unused formulas waiting to be explored and you can find many of them, at your disposal, in mb3d. So if you feel adventurous and ready to stray from the trodden path... wink
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sabine62.deviantart.com
Spain2points
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« Reply #9 on: August 23, 2017, 12:15:06 PM »

cool animations congrats
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Alef
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« Reply #10 on: August 29, 2017, 04:31:28 PM »

Nice fractals.

I think Navigator is slightly less good at navigation than Chaos Pro have.
http://www.fractalforums.com/chaospro/chaos-pro-inferiority-and-superb-navigation/
"Alsou in Chaos Pro Ctrl + left click adds a sphere with center and camera. Then you can increase radius or move camera where you want.  In another words you can manualy position camera enshuring that you'll see what you want." by me
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