Half-circle pieces (R=400) not optimally placed on 6500×2410 sheet

[ParthavK]

🔍 Problem Summary

When placing 36 half-circle pieces (radius = 400 mm) on a 6500 × 2410 mm sheet, the optimizer generates a non-optimal and inconsistent layout.

Instead of cleanly arranging pieces, the output includes:

• Staggered / uneven rows
• Irregular spacing
• Rotated pieces where rotation is not required
• A large unused region on the right side
• A layout far from mathematically optimal packing

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📐 Geometry Details

Each half-circle (radius 400 mm):

• Width = 800 mm
• Height = 400 mm

Since the sheet size is 6500 × 2410 mm, an ideal deterministic packing is possible:

• 6 pieces per row (6 × 700 = 4200 < 6500)
• 6 rows (6 × 400 = 2400 < 2410)
• Total = 36 pieces

Expected layout → a clean 6 × 6 grid with minimal waste.

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❌ Actual Output

The generated solution (solution_5.json) shows:

• Misaligned placement
• Unnecessary staggering
• Large unused space on right
• Non-deterministic layout even though an optimal structured pattern exists

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✅ Expected Behavior

The optimizer should return a layout similar to:

• 6 rows × 6 columns
• All pieces aligned
• No rotation needed
• Minimal unused space

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📁 Attached Files

▶ Input

input_5.json

▶ Output

solution_5.json

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🔄 Steps to Reproduce

1. Load input_5.json
2. Run the optimizer with default settings
3. Inspect resulting layout
4. Compare to deterministic optimal grid

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📌 Additional Notes

• The optimal layout is deterministic and straightforward.
• The optimizer should at least match this baseline.
• Potential causes: incorrect bounding box handling, rotation logic, or polygon resolution.

[fontanf]

Hi,

The solution of the solver has width 4493.65
The 6x6 grid solution has width 4800. Therefore, even if it looks nicer, it's not better than the solution of the solver

[ParthavK]

Hi sorry for that,

🔧 Correction to Earlier Description

In my original issue, I wrote:

“6 pieces per row → 6 × 800 = 4800 mm”

This was incorrect.

Because the pattern places one half-circle up and one half-circle down,
the two shapes interlock and require only ~700 mm of horizontal space per pair.

So:

• 6 up–down pairs use ≈ 4200 mm, not 4800 mm.

I have already attached an image with markings that visually shows this corrected measurement.
All other parts of the issue remain unchanged — only this calculation needed correction.

[fontanf]

This solution has width 4271, not 4200. It's possible to get it with allow_mirroring set to false, and without the 90 and 270 rotations.

With allow_mirroring set to false and the four rotations, the solver finds a better solution of width 4266.97

[ParthavK]

Still getting not optimised output.
Can you help me to change input and command to get optimise output.

I am using this command.
command = [
"./optimization/packingsolver_irregular",
"--verbosity-level", "1",
"--input", input_1.json,
"--time-limit", 500,
"--certificate", output_1.json,
"--optimization-mode", "Anytime"
]

input_1.json

[ParthavK]

Took too much time to get most optimised solution.

[fontanf]

In the last input you enclosed, the half-circle is describe using 1257 points. In the first one, it was 126. Even 126 is already high. Try using fewer points