Do Hidden Polygons Count?


A quick question regarding Polygon counts as this came up again in a thread earlier.

I often read about bloated models where the polygon count gets too high for SketchUp to handle and I wonder if hidden polygons count?

My standard workflow invariable involves importing a Point Cloud and creating a mesh from the relevant surfaces before taking a section. My total mesh polygon count often exceeds half a million and it doesn’t seem to slow anything down.

Generally my mesh groups are hidden once I’ve taken the section so my question is, can hidden Groups slow a model down?

Polygons are polygons. If the edges are hidden or visible does not matter when calculating the size of a model.

As far as displaying a model to the screen, edges are a big part of the “load” put on SketchUp. If you have edges turned on, it takes more work for SU to display a model. Hiding edges helps, but at the end of the day, the geometry in a model is what SketchUp is showing and the more of it there is, the harder your computer has to work to show it.

1 Like

Yes. Hidden polygons count. A polygon must have at least three edges and a face so they definitely have an impact.

That’s good but as that number increases your CPU and GPU have to work harder so …

1 Like

Thanks @DaveR & @TheOnlyAaron

So for good practice I will start to delete mesh groups after taking my sections. I can always recreate them in the unlikely event I need them again :+1:

Good. I would suggest deleting anything that has served its purpose and is no longer needed in the model. Purge unused components and materials periodically as well. Cleaning as you go will keep things working more smoothly.

Before you get to deleting your mesh, you might run Cleanup3 on it to merge coplanar faces. Not only will that reduce the number of polygons but it will also reduce the number of edge segments in your sections.

1 Like

honestly that’s big, but not massive. I expected point clouds models to have way way more.

problems arise when people have one couch that weight half a mil polygons. Recently someone had a bloated model, a single camera on a single night stand was more complex than your point cloud model.
that’s what makes a model bloated :slight_smile:

yeah, stuff that you can easily remake if needed can be deleted. and even if you have complex geometry that you don’t need anymore but that would be complex to remake, you can always copy it in its own separate file fore safekeeping.


You could also copy in place in a backup/reference file so you don’t have to regenerate in Undet again in case it’s needed.

EDIT - derp, as @ateliernab wrote.

1 Like

What a GREAT idea :+1:

Thanks for your reply.

Just to avoid confusion - the point cloud itself is usually 2GB - 10GB depending on how much of a building I bring in to SketchUp, but the plugin I use deals with that size of point cloud effortlessly.

The half a million or so polygons I referred to was for the mesh I create from the point cloud within SketchUp which I then use to create a section.

I like the idea of copying the mesh to another file just in case then deleting it :+1:

I don’t recall whether you’re using Trimble Connect but you can see here that a copy in place mesh (.skp) could be added to this mix:

I haven’t had luck getting things aligned in TC but you can have more than one PC if needed:

Thanks. I haven’t found a need for TC yet but I will certainly check it out. I currently save everything locally then auto backup overnight to an external drive that syncs to OneDrive. :+1:

1 Like

Amazingly, I’ve just deleted the mesh from a recent 90 scene model which generated over 60 Layout drawings and represented a good weeks work, and its only 1MB.

It seems as though I’ve produced almost nothing :rofl:

Example.skp (1.0 MB)