How to stop faces from flashing in SketchUp (z-fighing) ?

Z-fighting in SketchUp, where overlapping faces “flash” as you navigate the model, happens because two surfaces occupy nearly the same space. This makes it hard for the software to decide which face to display, causing a visual flickering effect. Here’s how to resolve it:

1. Adjust the Geometry

The primary cause of z-fighting is overlapping geometry. Fixing the model often resolves the issue.

Steps:

1. Check for Overlapping Faces:
   • Orbit around the affected area to identify overlapping or duplicated faces.
2. Delete Extra Faces:
   • If you find duplicate faces, erase one of them using the Erase tool or by selecting and deleting.
3. Separate Coplanar Surfaces:
   • Ensure no two surfaces are exactly coplanar unless necessary. Slightly offset one of them (e.g., by 0.01 mm) if overlap is unavoidable.

2. Use a Slight Offset

If overlapping faces are unavoidable (e.g., stacked objects), adding a tiny offset can help.

Steps:

1. Push/Pull Slightly:
   • Use the Push/Pull tool (P) to slightly move one surface away from the other.
2. Adjust Position Precisely:
   • Use the Move tool (M) to nudge one surface by a minuscule amount (e.g., 0.001).

3. Adjust Styles and Rendering Settings

Sometimes z-fighting can appear worse due to SketchUp’s rendering settings.

Steps:

1. Turn Off Back Edges:
   • Go to View > Edge Style and uncheck Back Edges.
2. Change Transparency Settings:
   • Open the Styles panel, go to the Edit tab, and under Transparency, choose Nicer to improve how SketchUp handles overlapping transparent surfaces.
3. Use Monochrome Mode:
   • Set your model to Monochrome (View > Face Style > Monochrome) to better identify and fix overlapping faces.

4. Group and Organize Geometry

Properly grouping geometry can help SketchUp manage faces better.

Steps:

1. Group Components:
   • Select faces or objects that belong together and group them (Right-click > Make Group).
   • Use components (Right-click > Make Component) for repeated elements.
2. Avoid Overlapping Groups:
   • Check that grouped objects do not occupy the same space.

5. Optimize Model Scale

If the model is very large or small, z-fighting can be exacerbated.

Steps:

1. Scale the Model:
   • Use the Tape Measure Tool to scale the model to an appropriate size. For example, very thin objects may need a larger scale temporarily to adjust geometry more precisely.
2. Reset View Clipping:
   • If z-fighting occurs during zoom-in or zoom-out, it may be due to camera clipping. Go to Camera > Field of View and set it to 35°–50°.

6. Use Extensions (Optional)

Extensions like CleanUp³ or Solid Inspector² can help detect and fix overlapping geometry in complex models.

By addressing these issues systematically, you can eliminate z-fighting and create a cleaner, more visually stable model in SketchUp.