Looking for fractal software with coloured 'voxel stack' export capabilities

[David Williams]

Hi all,

I'm the lead developer of a real-time voxel rendering engine (details here) and am looking for some data sets to test it on. Eventually I would like these datasets to be quite large (perhaps thousands of voxels wide?) so it seems to me that fractals might be a good way to go about obtaining these. I would like some help identifying software which can meet my needs.

I would like the software to create 3D fractals and provide the option of saving these to disk as a set of images representing slices through the fractal (a 'voxel stack'). These generated images should be in colour, or at least greyscale so that I can apply my own gradient mapping to colourise them. They should also be the 'raw' colours without any kind of lighting baked into the data.

I've done a little research myself and found that Mandlebulb3D offers a voxel stack export but it only seems to produce binary (black and white) images with no colour information. I've also seen people talk about using Mandlebulber and possibly setting up an animation to render out the slices? I've also come across Incendia though I'm not yet sure if the voxel export is in colour.

So, does anyone have any thoughts about which software (free or cheap) offers good voxel stack export capabilities? Is there anything interesting I have missed?

Thanks,

David

[Sockratease]

Hello and Welcome to the forums   

Mandelbulb3D can do color voxel slices by using the animation feature and manually adjusting the slices to match what the voxel feature does.  Just set the z start and z end accordingly  (probably -1 to 1 or -2 to 2 or something).

There is no actual coloring though.  All the 3D Fractal colors come from lights.  To get the result you want it may work to simply turn off shadows.

Hope that helps, I'm no expert but those seem like good preliminary ideas for your quest.  Maybe somebody better at this than I will come along with a better idea   

Enjoy the site   

[David Williams]

Great, thanks for the info. After I posted I spent some time trying to set up such a slice animation in Mandelbulber (rather than Mandelbulb3D which you suggest) and it looked like it should work in principle. Turning off lights, AO, etc did indeed give the required data and I could change the limits to select slices. My two remaining concerns where wherther the animation would interpolate the limits in a linear fashion (rather than cubic, which would distort the fractal) and whether I could set up an orthographic camera rather than a perspective one.

At any rate it sounds like I can try the same procedure in Mandelbulb3D so I give that a test and see how it compares. I also gave Incendia a go but found the user interface a little unintuitive.

There is no actual coloring though.  All the 3D Fractal colors come from lights. 

Right, knowing almost nothing about fractals I wasn't sure about this. Is your comment specific to Mandelbulb3D or to fractals in general? In Mandelbulber it appeared that colours were present with the lights turned off but I may have misunderstood something. It looks like there's a colour gradient defined which maps to, er, some fractal property :-)

Well I shall play some more tonight and post an image if I have any success.

[bib]

There is no actual coloring though.  All the 3D Fractal colors come from lights. 

I don't think so. At least in Mandelbulb3D, some color schemas are applied according to the fractal itself and how it's been calculated, no only external lights.

[David Williams]

I played with this a bit more last night, but now I have a new concern in that I think rendering slices is going to be too slow. A true 'voxel export' feature would only need to evaluate the fractal once for each voxel, but when slice rendering is being performed by raytracing I think a lot more work is being done even with lighting turned off. I can limit the ray traversal distance with near and far values but I still think a lot of work will be done.

My fairly old machine rendered a 1024x1024 slice in about 3 minutes, but that's about 3000 minutes (50 hours) for all 1024 slices to complete the volume. If I want a 4096^3 volume it's going to take 4x4x4 = 64 times as long so several months!

This may well be the reason why Mandelbulb3D limits the size of the export to 256^3, maybe it's just too expensive to go bigger. However, I'm going to have a go at writing my own C++ code to fill my own voxel structure to see how it performs. I've just started looking into the maths behind these fractals and it's beautifully simple :-)

I'll let you know how it goes.

[Jesse]

You can render 2D also, see the attached m3a animation example.
This should render a 4x4x4 sized room centered at the origin.

The voxel output is not limited in the size btw, only preview is limited to 256^3.

[David Williams]

Ah, thank you. It looks like the 2D animation is indeed a feasible way of getting the data I need, and I think Mandelbulb3D is makes this a bit more straightforward than Mandelbulber.

The voxel output is not limited in the size btw, only preview is limited to 256^3.

Right, I missed that. But is there a reason why the voxel export doesn't do the colours? I guess it's because most people want to convert it into a mesh for rendering, printing, etc and it's hard to run Marching Cubes on such colour data? Perhaps it would be interesting to export both sets of images (colour and binary).

Thanks again for your help!

[Mrz00m]

Oh cool, it must be great to have 3d maps made from 2d slices animations, like a 20 meg video would be smashing.

I'd suggest researching video formats, and use a format that can easily be converted to and from 8 bit color compression bitmaps. even 16 bit if there is enough room.

1024 cube is 1024 frames of video.. that makes 40 seconds of video 1000 000 000 pt array... how do you manage that?

[David Williams]

Thanks for the input, but this is quite an old thread so we're not actively looking at it any more. For those interested we ended up writing our implementation of Mandelbulb as a program which could output directly to our format. You can see and image here (near the bottom): http://www.volumesoffun.com/a-quick-update-and-some-new-screenshots/

Oh cool, it must be great to have 3d maps made from 2d slices animations...

Building map from voxel is a lot of fun :-) It lets us do cool in-game destruction like this: <a href="http://www.youtube.com/v/rhV2dcM4IkE&rel=1&fs=1&hd=1" target="_blank">http://www.youtube.com/v/rhV2dcM4IkE&rel=1&fs=1&hd=1</a>