Dimensions in Layout not accurate

I am laying out a house on a lot and need accurate measurements for the placement. It would seem Layout would be ideal for this since I can just use the dimension tool to show the distance from lot corners to house corners. However, when I do that, the dimensions in Layout are off by about 1 foot in 50 (compared to the dimensions in Sketchup).
I am inserting a scene from Sketchup (17), Parallel projection, standard top view. Why would it be so inaccurate?

Probably because you are dimensioning to points that aren’t in the same Z plane so you are dimensioning diagonals.

If you could share the LayOut file, it would be easy to make a proper diagnosis of the problem.

Ah, that would make sense. I didn’t think of that. The lot outline is slightly off plane from the base of the house (I never did figure out how that happened) but only slightly. I wouldn’t think it would make a difference of one foot in 50.

Yeah, it would take a height difference of about 10 feet to make a 50 foot horizontal read as a 51 foot diagonal. But how are your units set? If you are using whole feet, you could be seeing something that is close to 50 1/2 feet getting rounded down when it is level and up when it is a diagonal that is just a small amount longer.

OK, I just fixed the lot to put it in plane with the foundation, and when I updated the model reference in Layout, it did change the dimension - by about an inch. Still about a foot off. The dimensions are in feet and inches.

Hmmm…how about horizontal alignment? Just grasping at straws here, since we don’t have the model…

Horizontal alignment in what respect?

How do I share the file?

When you reply, in the text editor there is a button for uploading files.

Lot Dimensions.skp (559.5 KB)

Well, that’s weird. The file I just uploaded is one that I deleted all the extra stuff from but the walls and lot outline, but it’s the same otherwise. I saved it as a different file. I just inserted this into a Layout file, and the dimensions come out the same in SU and LO. So now it’s even more mysterious.

That suggests you need to look carefully at “all the extra stuff”!

Do you have the LayOut file with the goofy dimensions?

Yes, but none of that should have anything to do with a measurement between the corner of a wall and the corner of the lot outline. The extra stuff is things like the roof, trusses, windows, kitchen, pool, etc.

If the problem goes away when you delete something, doesn’t that strongly suggest that the something was involved, even if it doesn’t seem to make sense? Perhaps dimensions were snapping to the roof eaves, which are about 10 feet off the ground?

It suggests it, but since all those things that were deleted were also the things not visible (by layers) which should act essentially the same. Also the eaves are 24" out, which would indicate wrong dimensions in the other direction (besides the fact that I can clearly see it referencing the corner of the foundation).

After studying this some more, I think I have figured it out. I believe layout has been measuring from the the top of the wall (which is about 10 feet high), not the foundation, and it just appeared that it was measuring from the foundation since it was in Parallel projection. This is basically what slbaumgartner and DaveR were suggesting. I don’t know why, when I deleted the roof and such, it measured from the base of the wall instead of the top.

So the lesson learned here, if you want accurate measurements of this type, don’t use a parallel projection of the walls, use a section cut at the foundation, or just use a plane of the foundation for the measurements.

I have also had a lot of problems with getting the inferences I want in Layout. what I do as a work around is to put the dimensions in layers in the sketchup model export to Layout add the dimensions in layout to check their accuracy then go back to the model hide the dimension layers (save changes) and update the the references in Layout. A little clumsy, but better than a costly mistake in the field.

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It would be very handy if Layout would have a “project” feature, that would force all dimensions to be at the same plane, no matter what height the point is. Usually, when you are measuring from a plan or section, you are looking for points projected to that plane. That “project” feature could be a “toggle” in case there would be a situation where you need actual dimensions from one point to the other, at different planes.


Since LayOut is working with a 2D view of a 3D object, I think this would be a valuable capability in LayOut. Of course, unless the SketchUp scene being viewed in LayOut is parallel projection and one of the cardinal directions, there would need to be a way to tell LayOut what plane you want the measurements projected to.

I have had this issue many times, and the problem always turns out to be that the view is slightly off-axis. I know you said your view was standard top, but if you’re half a degree off from vertical the misalignment is probably not visible, and the SketchUp model window will still say “Top” at the upper left-hand corner, but that only means you’re close. To confirm your LayOut view is truly orthographic, check the Standard Views drop-down in the SketchUp Model pane. It should say “Top” or whatever view. If it says “(None)” your view is off-axis and your dimensions can snap out of plane. Fix that, and your dimensions should fix themselves.

Views that are perspective instead of parallel will have the same problem, but that’s usually pretty easy to spot.