3d_modeling:blender:clean_up_occipital_3d_scan

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3d_modeling:blender:clean_up_occipital_3d_scan [2020/04/06 09:09] – formlab3d_modeling:blender:clean_up_occipital_3d_scan [2021/10/13 00:23] – [Open the file] formlab
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 ====== Clean up a 3D scan made with the Occipital Structure scanner ====== ====== Clean up a 3D scan made with the Occipital Structure scanner ======
-The 3D files from the Structure scanner often have holes and unwanted geometry. After following this guide you'll get a watertight model that is ready for color-3D printing. A basic understanding of mesh manipulation in Blender is necessary. 
-We will use Blender, but here is a [[3d_modeling:meshmixer:clean_up_3d_scan|guide]] that describes this process for Meshmixer. 
  
 +The 3D files from the Structure scanner often have holes and unwanted geometry. After following this guide you'll get a watertight model that is ready for (colour) 3D printing. A basic understanding of mesh manipulation in Blender is necessary.
 +This guide uses Blender, but here is a [[3d_modeling:meshmixer:clean_up_3d_scan|guide]] that describes this process for Meshmixer.
 +
 +
 +===== Open the file =====
 +The structure scanner delivers the 3D object in 3 parts:
 +  * ''Model.obj'' is the 3D object
 +  * ''Model.jpg'' is the texture file
 +  * ''Model.mtl'' is a file that links the object to the texture.
 +{{:structure_3d_scanner:cleanup_files.jpg?nolink|}}
 +
 +You only have to open the ''.obj'' file. The program will find the other files on its own:
 +  * ''File > Import > Wavefront (obj)''. Choose the ''.obj'' file
  
 ===== Setup the mesh ===== ===== Setup the mesh =====
-  - Import the mesh. 
   - Make the mesh active (yellow contour lines instead of orange) ''left mouse click''   - Make the mesh active (yellow contour lines instead of orange) ''left mouse click''
   - Right click on the mesh and select ''Set Origin > Geometry to origin''.   - Right click on the mesh and select ''Set Origin > Geometry to origin''.
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   - Hover the cursor over the mesh you want to keep and press ''l'' (lower caps L).   - Hover the cursor over the mesh you want to keep and press ''l'' (lower caps L).
   - Invert the selection: ''Select > Invert'' (shortcut: ''cmd + i'')   - Invert the selection: ''Select > Invert'' (shortcut: ''cmd + i'')
-  - delete the selected vertices ''Mesh > Delete > Vertices'' (shortcut: ''x > Delete Vertices'')+  - Delete the selected vertices ''Mesh > Delete > Vertices'' (shortcut: ''x > Delete Vertices'')
  
 {{:3d_modeling:blender:03_delete_geometry_-_loose_-_collage_-_arrows.jpg|}} {{:3d_modeling:blender:03_delete_geometry_-_loose_-_collage_-_arrows.jpg|}}
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 The 3D scanner generates a mesh with messy topology. There are areas with very large faces, and others where there are lots of vertices crammed together. This creates visible stress points in the mesh. The relax function moves the vertices away from densely populated areas in order to be more equally distributed. Having the mesh relaxed will prevent a series of problems later on. This will change the shape of the mesh a little bit though. The 3D scanner generates a mesh with messy topology. There are areas with very large faces, and others where there are lots of vertices crammed together. This creates visible stress points in the mesh. The relax function moves the vertices away from densely populated areas in order to be more equally distributed. Having the mesh relaxed will prevent a series of problems later on. This will change the shape of the mesh a little bit though.
  
-  - select all vertices ''a''+  - Select all vertices ''a''
   - Relax Vertices: ''Vertex > Relax''. A single iteration will do.   - Relax Vertices: ''Vertex > Relax''. A single iteration will do.
 {{:3d_modeling:blender:03_delete_geometry_-_relax.gif|}} {{:3d_modeling:blender:03_delete_geometry_-_relax.gif|}}
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   - Scale down the selection in the UV editor and position it over a not yet textured area.   - Scale down the selection in the UV editor and position it over a not yet textured area.
   - Switch to the Texture Paint workspace, Select the clone brush and set the source for the brush ''Ctrl + left mouse click'' (the 3D cursor will indicate the position). Now you're ready to draw.   - Switch to the Texture Paint workspace, Select the clone brush and set the source for the brush ''Ctrl + left mouse click'' (the 3D cursor will indicate the position). Now you're ready to draw.
 +  - After drawing **save the texture image(!)**. Otherwise you'll have to redo the work.
  
 {{:3d_modeling:blender:05_hole_retexture_-_collage_arrows.jpg|}} {{:3d_modeling:blender:05_hole_retexture_-_collage_arrows.jpg|}}
 ==== Big Holes ==== ==== Big Holes ====
-When the holes are big, closing them with ''Vertex > New Edge/Face from Vertices'' (shortcut: ''f'') results in a flat surface. Here are two ways to reconstruct the natural curve of the object. Clean up the edge of the hole as described above.+When the holes are big, closing them with ''Vertex > New Edge/Face from Vertices'' (shortcut: ''f'') results in a flat surface that interrupts the flow of the shape. Here are two ways to reconstruct the natural curve of the object. Clean up the edge of the hole as described above.
  
 === Using Grid Fill === === Using Grid Fill ===
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 Clean up dark spots by resetting the normal vectors: Clean up dark spots by resetting the normal vectors:
-  - go to Edit Mode +  - Go to Edit Mode 
-  - select all vertices+  - Select all vertices
   - ''Mesh > Normals > Reset vectors''   - ''Mesh > Normals > Reset vectors''
-  - go back to object mode+  - Go back to object mode
  
 {{:3d_modeling:blender:06_big_hole_-_gridfill_-_09_edge_cleanup_collage_arrows.jpg|}} {{:3d_modeling:blender:06_big_hole_-_gridfill_-_09_edge_cleanup_collage_arrows.jpg|}}
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 This is more tedious, but it allows for better control over the shape . This is more tedious, but it allows for better control over the shape .
 +
 +{{:3d_modeling:blender:06_big_hole_-_manual_comparison_collage_arrows.jpg|}}
  
   - With the edge vertices selected, go to ''Vertex > New Edge/Face from vertices''. (shortcut: ''f'') to fill the gap with a single n-gon.    - With the edge vertices selected, go to ''Vertex > New Edge/Face from vertices''. (shortcut: ''f'') to fill the gap with a single n-gon. 
   - Shape the n-gon step by step by selecting opposing vertices and joining them: ''Vertex > Connect Vertex Path'' (Shortcut: ''j''). This will not create overlapping faces, but instead divides the current n-gon in half. The new vertex path will include any edge it runs through. This method allows you to define the new surface in steps, going from a rough definition to fine surface details.   - Shape the n-gon step by step by selecting opposing vertices and joining them: ''Vertex > Connect Vertex Path'' (Shortcut: ''j''). This will not create overlapping faces, but instead divides the current n-gon in half. The new vertex path will include any edge it runs through. This method allows you to define the new surface in steps, going from a rough definition to fine surface details.
 +
 +{{:3d_modeling:blender:06_big_hole_-_manual_collage.jpg|}}\\
 +Gradually defining the shape
 +
 +Tips:\\
 +  - Move vertices along the edges they're connected to: ''Vertex > Slide Vertices'' (Shortcut: ''shift + v'' or ''double tap g'')
 +  - Get a smoother result with proportional editing enabled
   - If you need to delete elements (vertices, edges or faces), dissolve rather than delete them. ''Mesh > Delete > Dissolve ...'' (shortcut: ''ctlr + x'') This way you keep the existing faces intact instead of making a hole.    - If you need to delete elements (vertices, edges or faces), dissolve rather than delete them. ''Mesh > Delete > Dissolve ...'' (shortcut: ''ctlr + x'') This way you keep the existing faces intact instead of making a hole. 
  
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 ===== Normals ===== ===== Normals =====
- 
-<wrap hi>Maybe better after having a watertight object</wrap> 
  
   - Go to edit mode and select all vertices   - Go to edit mode and select all vertices
-  - Recalculate normals: ''shift + n'' +  - Recalculate normals: ''Mesh > Normals > Recalculate Outside'' (Shortcut: ''shift + n''). 
-  - **IMG** Show the face normals for a visual check. In Edit mode: ''Overlays > Enable face normals''. +  - If the visualisation lines are pointing inwards, select all vertices, ''Mesh > Normals > Flip''.
-  - If the blue face normals are pointing inwards, select all vertices, ''Mesh > Normals > Flip''. +
-  - **IMG** These spots are caused by split-normals that are stuck in the wrong direction. +
-    - To fix this, select all vertices, ''Mesh > Normals > Split'', and then ''Edge > Clear Sharp''+
  
-  - **IMG** These problems are visually similar to the wrong facing split-normals, but it's caused by clunky geometry.  +{{:3d_modeling:blender:07_normals_outside_collage_orig_arrows.jpg|}}\\ 
-    - If it's caused by vertices that are close to each other, run a [[https://docs.blender.org/manual/en/latest/modeling/meshes/editing/cleanup.html#degenerate-dissolve|Degenerative Dissolve]]. ''Mesh > Clean Up > Degenerate Dissolve''. Try increasing the merge distance in small steps. +Show the face normals for a visual check. In Edit mode: ''Overlays > Enable face normals''.
-    - If it's caused by a small overlap, Fix the geometry by merging some of the problematic vertices. Avoid having to make new faces, because then you'll have to redo the texture on that face.+
  
  
  • 3d_modeling/blender/clean_up_occipital_3d_scan.txt
  • Last modified: 2021/10/13 03:07
  • by formlab