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I've only started using blender 2 days ago. So i'm sorry if this is really stupid. Im not sure what keyterms to search for. but had no luck so far in getting a solution.

  1. So, I have a landscape mesh (Another Noise Tool - Landscape), and it is hollow.
  2. And I want to set it on a circular plane.
  3. but I want to cut out the overlapping part of the circular plane (i highlighted in blue) so I can still see inside the landscape mesh from the bottom.

Essentially, I want the landscape mesh on a circular ground instead of the square it came in. This is the way I thought of going about it. But if there's a more straightforward way, i'd be happy too.

Because the issue with the method I'm trying, it is hard not to have a difference in x-axis between the landscape plane and the circular plane which i circled in green.

I hope you could guide me through it. Thanks!

landscape mesh landscape mesh on circular plane part i wanna cut out x-axis difference

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3 Answers 3

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The most simple way would be if you have the Loop Tools addon enabled that comes with Blender.

  1. Select the outer edge of the landscape.

select border

  1. Right-click and choose Loop Tools > Circle.

loop tools

  1. The resulting circle will most likely be too small, so while it's still selected press S to scale it larger and left-click to confirm when you like the size.

small circle

Finished!

result

Here a quick summary viewed from the bottom since it seems hard to imagine that the bottom is open as desired:

bottom view summary

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  • $\begingroup$ OP wants the mesh to be open at the bottom, so your answer is missing that part $\endgroup$
    – Luciano
    Aug 3, 2022 at 14:48
  • $\begingroup$ @Luciano Follow my instructions exactly and look if the bottom is closed... $\endgroup$ Aug 3, 2022 at 14:51
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    $\begingroup$ oh I'm sorry, of course you're right! That's brilliant. I just read through it too quickly, I thought you were doing boolean with a plane... $\endgroup$
    – Luciano
    Aug 4, 2022 at 15:07
  • $\begingroup$ @Luciano No, the boolean workflow is in my other answer 😁 And there the bottom is open as well. $\endgroup$ Aug 4, 2022 at 21:23
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You'll need to extrude the outer edge a bit and fill that face to make the thing solid.

enter image description here

enter image description here

Then just add a cylinder and use a Boolean modifier with the mode set to Intersect.

If you have the Bool Tool addon enabled (comes with Blender) then you just select the cutter, shift-select object you want to cut and press Ctrl+Numpad /.

Result:

enter image description here

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  1. First of all you have your landscape.

landscape

  1. Next you add a cylinder with a not too low resolution. Make it large enough to completely cover the landscape and place it so that the bottom is slightly above the landscape's ground plane.

add cylinder

  1. Now add a Boolean modifier to the cylinder. Choose the landscape as the other Object and set the mode to Difference (you can hide the landscape from view to see the result better). Now you have cut the landscape out of the bottom of the cylinder.

landscape hole

  1. Next apply the modifier by hovering your mouse over it and pressing Ctrl+A. Tab into Edit Mode to select the top face of the cylinder. Then press X > Delete > Vertices (important - not Edges or Faces).

delete top face

  1. It remains the landscape with a circular ground plane. The only problem now is, that the faces are pointing in the wrong direction, because the outside of the landscape was the inside of the cylinder. If you enable Face Orientation in the Overlays you can see this by the red color instead of blue.

face orientation

  1. To change this, select all faces by pressing A then Alt+N > Normals > Flip. Now everything is correct and the top side of the landscape is blue.

result

The good thing is, the original landscape is still unaltered so you can use it again if you want to redo it slightly different.

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