Edge Extrusion Flips Normals

DELFTship forum Hull modeling Edge Extrusion Flips Normals

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    • #44459
      Terrance Egolf

      Not sure if this is a common problem, but when modeling 19th-century wooden sailing ships, there are a lot of opportunities to create features using the various extrusion tools in the program.

      One issue I have run across frequently is the flipping of surface normals when using the Edge Extrusion tool in the Edge submenu.

      Here is an example showing the edge extrusion of simple cylinder object to the right. After the extrusion, the surface shows the characteristic surface color transition where the normals flip to the inside. You can verify this by showing the surface mesh in the Wireframe view and turning on the Normals view in the Hull Display submenu.


      This problem is not too difficult to correct in simple objects. However, when creating a fancy roof cornice for an older ship, it can get really ugly, selecting all those small faces and having to flip their normals manually:


      I, for one, would like to see this issue corrected.



    • #44464

      Hi Terrance,

      It is true that, after extruding, DELFTship does not always ‘knows’ the proper direction of the normals.

      At the risk of inverting a lot of manually set normals (make sure you save before you do this!) what happens if you do a ‘Check model’? This should re-calculate all normals in the model.

    • #44467
      Terrance Egolf

      Thanks, Maarten.

      I tried that feature and it corrected the normals on the cylinder example in my previous post.

      Do you know if this action always applies to objects in hidden layers? Or can you select an object and have the Check Model action apply only to the selection? The latter would be a nice feature to have if you want to just check a specific object.



    • #44479

      Hi Terry,

      The ‘Check model’ normals function needs to check the entire model- as the orientation of normals are interdependent.

      In theory we could check the normal orientation of parts that are not at all connected to any other parts , but I am unsure if this would help your case.

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