First find the convex hull of all tiles. Then, ... I calculate the minimum circle by doing it with brute force...The algorithm is fast enough for all practical examples, I checked.

Indeed. As all your points live on a regular grid and large numbers of them will be 'inside'; and of the outermost, many will be eliminated by being co-linear, the convex hull should always reduce to a manageable number for brute force.

For quite a while I thought that -- for the specific case of your regular grid -- the convex hull algorithm could be avoided by finding the 3 points 'by inspection'. Indeed, if your tiles were square, it is, but for the generality of rectangular tiles, I couldn't find a reliable way.

I have to say, it offends me intellectually to know that there are several O(n) algorithms (for the {smallest/minimum/bounding} {enclosing/encircling/} {circle/disk/ball/sphere} problem) out there, and yet I found it impossible to find either a clear description; or a correct and usable implementation :(

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.

In reply to Re^9: Placeing Tiles in a Circle by BrowserUk
in thread Placeing Tiles in a Circle by janDD

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