Solving 2d cutting stock problems with guillotine cut via OptaPlanner

[nazem...@gmail.com]

I ve been  trying to solve a 2d cutting stock problems , the joint file shows a feasible solution delivered by column generation technique.
I  tried to resolve the problem using OptaPlanner , but after several attempts I didn't get good results. I m quite inexperienced with the planner, and I want to confirm its fitness
to solve such problems as none of the problems explored in the documentation are close to 2d cutting stock.

[Geoffrey De Smet]

Guillotine cuts - and 2D surface packing in general - require a non-simple model.
Like 2D surface packing or 3D volume packing, the trick is often to use Local Search to decide an order of items
and then use that order in a Construction Heuristic or greedy approach to decide the actual packing/cuts.
Similar to what I did here: https://github.com/ge0ffrey/packing-santas-sleigh

In any case - it's far from straightforward to do in OptaPlanner 7.x or lower, as you'll see in that Santa code.

With kind regards,
Geoffrey De Smet
OptaPlanner lead

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[Prakash Dutta]

Hello Geoffrey

If the pieces which need to cut from the stock piece are in differnet shape(star, circle, rectangle, square etc), then how the CSP problem should function so that we can minimize the final waste?

Regards,

Prakash

[Geoffrey De Smet]

need to cut from the stock piece are in differnet shape(star, circle, rectangle, square etc)

OptaPlanner does not handle this use case (2D surface cutting of polygons) easily out of the box.
Although as far as I know, nor does any other production solver...

The trick is to use Local Search on top of a Construction Heuristic (so not LS after CH as usual, but instead LS on top of CH).
The Local Search creats a list of shapes. The Construction Heuristic puts them in the left bottom corner, in the order of that list created by Local Search.
You could hack OptaPlanner - like I did in the packing santa sleigh's problem (see my github repo).

This will be a challenge.
Good luck.

With kind regards,
Geoffrey De Smet

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