1. Limit Excessive Geometry

Look for opportunities to use the least number of segments on curved work. Models and model details made with arcs and circles can make the model size get out of control. In particular, try to use fewer segments in the following situations:

    • On arcs of shorter length or larger radius (flatter curves). You may get away with only using 3-segmented arcs instead of the default 12-segmented ones.

  • On circles of smaller diameter, use less than the default 24-segments for circles.

As long as the Arc/Circle/Polygon tools are active, you can repeatedly change the segmentation by typing the desired segment number followed by s, like 5s.

After switching to another tool, change the segmentation through the Entity Info dialog.

  • When you plan to use the arc as part of a Follow Me extrusion, either as the profile or the path, this compounds and multiplies the impact on file size of unnecessarily fine-grained curves.

  • Where the effects of fewer segments will not be as apparent because of smoothing or because the curved surface will not present a prominent profile,

Banish 12-segmented softened edges

There are low-poly options when just softening an edge lacks visual dimensionality, and the default 12-segmented arc adds too much geometry. Note: this animation toggles on and off the Hidden Geometry, which is available through the View menu. The edges were softened with Erase+Ctrl (PC) Erase+Option (Mac).

Yet another reason to reduce segmentation

One of the special things SketchUp can to is depict coplanar surfaces as a single face, a polygon (many-sided face), while other formats triangulate everything (3-sided faces). As shown below, an 8-sided circle is composed of at least 6 triangle while a default-segmented, 24-sided circle has 22 triangles 'under-the-hood'.

So a model's triangular face count can be a lot higher than SketchUp's reported poly count. For example: Using SketchUp (and Unity) to craft stunning game environments.

How low can you go

- and be happy....

Each edge is a vector, a mathematically defined line in 3D space. And each face is a plane, bound by at least three vectors. Every time something changes in SketchUp, whether a camera move or creating new geometry, all those vectors and plane locations have to be recalculated relative to the change(s) to be rendered properly on the computer screen. So fewer edges/faces reduce the computer workload.

Modeling some things can be a balancing game, depending on what is needed. In an architectural rendering, components positioned in the distance will not be examined closely do not require the same amount of detail as something positioned closer to the camera (read how surface shading is affected by curvature segmentation.) At the opposite end of the spectrum are the highly detailed models required for 3D printing.

Original Spindle profile

235 segmented profile

lathed around 24s circle

13246 edges

6475 faces

Simplified Spindle Profile

72 segment profile

lathed around 12s circle

1764 edges

871 faces

Simplified Spindle Profile

72 segment profile

lathed around 8s circle

1189 edges

587 faces

Simplified Spindle profile

64 segment profile

lathed around 8s circle

1068 edges

530 faces

Simplified Spindle profile

64 segment profile

lathed around 6s circle

812 edges

400 faces

Simplified Spindle profile

64 segment profile

lathed around 4s circle

552 edges

274 faces

Simplified Spindle profile

54 segment profile

lathed around 8s circle

861 edges

462 faces

Simplified Spindle profile

54 segment profile

lathed around 6s circle

657 edges

322 faces

Simplified Spindle profile

54 segment profile

lathed around 4s circle

449 edges

222 faces

Components assembled with both low-poly geometry and Face Me component

Face Me Component Spindle

30 edges

13 faces

Here just the turned region with heavy geometry was substituted with a PNG image that was made into a Face Me component - when creating a component check the box "Always face camera."

Something like this could be used as a proxy component, which will look like a detailed model at a distance.

To create a credible, low-poly shadow, draw a rough outline resembling the spindle in the transparent margin and remove the excess. This example added 22 edges to the component.

Use Erase +Shift to hide the edges. Or select the edges and check the HIde box in the Entity Info window.

Landscape with Alpha Channel Images

Screw It

Here SketchUpper John McClenahan made a glueing component with a nested Face Me component, using minimal geometry and a transparent PNG image for the Face Me component central screw shaft to model a woodscrew.

Model as shown (two pieces of wood and two screws) - 70 Kb on disk. Adding 100 instances of the screw component only increase the file a few bytes, growing to 74 Kb..

The woodscrew component - with the Face Me inner component selected.

◄◄◄ The woodscrew component - with the Face Me inner component selected. Rethinking how common fasteners, like a Hafele minifix, can be efficiently depicted is another common issue faced by many people. Review Import 3D files, -what to do? to learn more about how modelers like John McClenahan discard the overly detailed, manufacturers CAD library files for models which will function better in SketchUp when added in large quantities. Model your own screws, following tips on this page or John's instructions posted in Import 3D files, -what to do?, or download more screw models from John's 3D Warehouse woodscrew collection - whatever. Adding screws like this will not bog down a SketchUp file.

More Examples to Study

  • Too Many Segments Sage George Knowles demonstrates how too many segments can slow down SketchUp performance AND be visually unnecessary.

  • Slow Performance Explore how highly detailed cabinet knobs can bog down a model AND be visually unnecessary.

  • errors importing DEM Don't import unnecessarily large files into SketchUp when there may be an alternative.

Materials/Textures

Substitute a texture to depict an otherwise high-poly modeled elements - i.e., a transparent PNG image of fencing instead of modeling fencing with lots of geometry - continuing .

    • landscape with alpha channel images, using low-poly 2.5D landscape components. The animation to the right is such a component. The tree canopy are 2 PNG images with casting shadows disabled. The shadow planes are a low-geometry planar outline painted with a 100% transparent PNG material.

    • Faking massive amounts of trees discusses using images instead of models with trees. xxx [dead link]

    • Avoiding Excessive Geometry Ross Macintosh tutorial on using images instead of models. xxx [dead link]

    • Polyreducer Whaat - The beginning of a SketchUp plugin to reduce the poly-count of some imported models. Whaat later incorporated this feature in his commercial plugin, Artisan.

    • Some people use the program Blender for poly-reduction.