*Continued* SuperFractalThing: Arbitrary precision mandelbrot set rendering in Java.

[hapf]

I like your dots!

 
The glitch looks like overskipping...

[Kalles Fraktaler]

 
The glitch looks like overskipping...

Yep, that is the famous series-approximation-glitch...

[stardust4ever]

Here's a stardust4ever inspired location for your enjoyment.  

I like your dots!

 
The glitch looks like overskipping...

I was referring to the coordinates you posted earlier with the little dot-like patterns .... .... . .... .... The glitch pic was on an unrelated topic in the same post.

[stardust4ever]

Yep, that is the famous series-approximation-glitch...

Yeah. There were two really knarly glitch frames in the "Simply Awesome II" video frames I rendered a while back (I never posted video online). It is a reworking of my first deep Mandelbrot zoom.
http://sta.sh/01aqqf7kg83r
http://sta.sh/017skb4ouloa

That second link is the classic example of a worst case scenario, when you zoom outside of a minibrot and the resulting periodic double results in dense dumbbell like formations. I probably just leave them in there at this point than risk corrupting my frame data trying to fix them. Kalles Fraktaler is not alone as Mandel Machine screws up too on occasion.

PS - You get my PM regarding audio tracks?

[hapf]

Yeah. There were two really knarly glitch frames in the "Simply Awesome II" video frames I rendered a while back (I never posted video online). It is a reworking of my first deep Mandelbrot zoom.
http://sta.sh/01aqqf7kg83r
http://sta.sh/017skb4ouloa

That second link is the classic example of a worst case scenario, when you zoom outside of a minibrot and the resulting periodic double results in dense dumbbell like formations. I probably just leave them in there at this point than risk corrupting my frame data trying to fix them. Kalles Fraktaler is not alone as Mandel Machine screws up too on occasion.

PS - You get my PM regarding audio tracks?

When you render these frames without skipping are they correct? I guess so. Is the real reason for the problem known? I think I know what this is about.

[hapf]

I was referring to the coordinates you posted earlier with the little dot-like patterns .... .... . .... .... The glitch pic was on an unrelated topic in the same post.

I got that. I saw no "dots" since I did not colour it that way. What structures you see depends a lot on how you colour a fractal.

[stardust4ever]

When you render these frames without skipping are they correct? I guess so. Is the real reason for the problem known? I think I know what this is about.

I have found what typically causes glitch frames when doing zoom out videos in Kalles Fraktaler typically occur at fork points, ie the explorer has diverted the path off from the centroid, especially true with dense or complex features. Also as each zoom out frame contans the previous frame within it, only the outer 3/4 of pixels are rendered, so the glitch may be present in only one of the frames resulting in the frame border masking a portion of the glitch. I am currently rendering a zoom movie through the area. I do not know why, but color cycling causes massive slowdown when generating the AVI files.

I have also experienced at times glitches occuring at very deep zoom levels in Mandel Machine, but such glitches can usually be resolved by recentering the image. Sometimes it is fun to save or screengrab these mistakes. Typically they appear as oblong circles. Think deflated beach ball.

I got that. I saw no "dots" since I did not colour it that way. What structures you see depends a lot on how you colour a fractal.

Your "dots" are actually pairs of smaller dots. I did not zoom in for close detail.

[quaz0r]

you guys must have your series approximation set to bail too late?  which works out often enough...until it doesnt.  i noticed on the mandel machine thread that he mentioned using a single order of magnitude in his check, whereas ive found that 3 prevents these glitches from occurring.  i havent encountered these glitches since i started doing it this way, though i havent gone super super deep very often like some of you guys do, so maybe even more vigilance is required than that, im not entirely sure?  do any of you guys have this totally figured out for sure?  claude maybe?  KF and MM must still be too aggressive if they go off the rails still.

[claude]

I use something based on Botond's technique, but while it seems to work almost all the time I just came across what looks like a bizarre glitch near the end of a very deep zoom sequence (not to mention the aliased distance estimate moiré patterns being ugly-as).

[stardust4ever]

I use something based on Botond's technique, but while it seems to work almost all the time I just came across what looks like a bizarre glitch near the end of a very deep zoom sequence (not to mention the aliased distance estimate moiré patterns being ugly-as).

Could you maybe tweak the color pallet or cycling? Nearly the entire image is black save for a few dots. Hard to tell what is going on in there...

Here's a classic example of a "deflated beach ball" glitch I found not long ago in Mandel Machine. It is from just before the periodic double of the previously mentioned 1024X coordinates that Kalles Fraktaler posted. I first found this location by manually zooming and this glitch popped up at 3470 zoom levels. I have attached the mmf file (.ZIP). Sometimes a simple readjustment of the window will correct these glitches. They aren't super frequent but do crop up from time to time at very deep zoom levels. However I've yet to find a location that doesn't render properly after zooming into the centroid a few levels and backing up. It's more bothersome when it occurs within a zoom movie. There's supposedly a way to rerender individual KF frames but I don't know how and am too scared of corrupting the zoom out frames.

Edit: I tweaked the location a bit. There is a roughly ring shaped area surrounding the central X formation. Centering the image within this somewhat narrow iteration band will result in glitch formations every time. Subsequent renders of pixels inside the blacked out area generally show up properly. You can clearly see one of the arms of the "X" formation unobscured by the glitch pixel area. Try downloading the ZIP file (contains the MMF parameters) and use the rectangle tool to adjust the center of the image. Hint: you may want to disable super-sampling if it takes too long to render.

[quaz0r]

I've yet to find a location that doesn't render properly after zooming into the centroid a few levels and backing up.

yeah, that gives you a better initial reference point which would be more resilient to these glitches.  a crap reference point like when you go off-center maximizes the potential for these glitches to come through.

[stardust4ever]

yeah, that gives you a better initial reference point which would be more resilient to these glitches.  a crap reference point like when you go off-center maximizes the potential for these glitches to come through.

Not sure if you got my full post as I was making edits but there appears to be a donut shaped region with a certain range of iteration values that produces the glitch, every time. Try moving around the reference point. Farther out, the glitch disappears leaving a circular hole, which gets filled in by a centered reference point. Closer in to the target formation and the glitch disappears leaving a hole roughly shaped like the target formation.

[Kalles Fraktaler]

My feeling is that the first reference is too deep, it has connections to a deep minibrot
To put it more artistic and intuitive
If the first reference is put anywhere else it looses the deep connection, and all glitches are detected

Stardust, you can use the "examine zoom sequence" to browse the key frames and correct them if needed

[hapf]

Two remarks:

- How much skipping is safe is not easy to find out without actually computing errors all over the image. One can use methods like Botond's
 (all contributions right of coefficient x must be much smaller than left of... but how much much smaller is small enough??)
- The corruption trigger  1/10000  is often safe, but not always! And it's also often too conservative meaning there is no need to switch to
 another reference just because this threshold was hit. The pixel might be all fine iterating to the end.

Combine the two and safe error free images in all cases with optimal skipping and minimal references are not trivial at all to get.
 

[quaz0r]

it seems this is the last big hurdle that needs to be properly solved for the series approximation / perturbation technique to be considered good to go / non-experimental.  so far it seems we've all been more or less silently agreeing to lie to ourselves a bit and pretend that this is basically already good to go, though of course in reality if something only works "maybe" or "some of the time" or "to a certain degree" or "its anybody's guess," it is not in fact good to go.  you geniuses need to figure out how to nail this stuff down once and for all