Converting 3D to 2D plan | measurement issue important!

Hello everyone, I work in the solar energy industry, creating plans. To streamline this process, I first develop a 3D model of the house roof with solar panels using SketchUp. Subsequently, I aim to create a 2D plan in AutoCAD by directly converting the SketchUp model into a DWG file, employing top view and parallel projection techniques.
However, I have encountered an issue regarding the consistency of measurements between SketchUp and AutoCAD. Despite my efforts, I have found disparities that need to be addressed to ensure accurate design implementation.
I am writing to seek advice or solutions from anyone who might have experience or insights into resolving this discrepancy. Your assistance would be greatly appreciated.

The most common reasons for dimension disparities are having Lengtth Snapping enabled and coarse Display Precision set in SketchUp and/or not having the Camera set to Parallel Projection and the appropriate Standard View before exporting the .dwg file.


And ofcourse you could use Layout to produce 2D plans. It comes with SketchUp Pro.

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Post a model that shows the inconsistency you are talking about, and examples of the disparities so forum members can take a guess at what causes your troubles.

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Thanks for your help, but I’m encountering an issue with the tiled roof. Even when I utilize Parallel Projection and the top standard view, there’s still a difference between the 3D and 2D measurements. Although it’s not a significant gap, it mainly affects widths or lengths.

Have you read Dave’s advice on length snapping and display precision??

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yes, but problem not solved

This is my roof 3D model in SketchUp with measurements.

This is when I use parallel projection to view the roof from the top in SketchUp.

This is the final result I aim for when exporting the SketchUp file to AutoCAD DWG format to create a 2D plan. However, you’ll notice a difference in the length of the roof and solar panels.

In SletchUp your dimensions are along the angle of the roof. In your 2D CAD drawing they are horizontal dimensions. This is basic geometry. You aren’t measuring the same thing in both views.


In the first two images you show the sloping dimensions of the roof and in the last image they changed into the horizontal dimensions of the roof.
sup dimensions horizontal or sloped

When converting from 3d to 2d, the cad software does not know the lines are sloped since the 3d dimensions got lost during the conversion.

It’s the same way when converting 2d drawings into a 3d drawing, the dimensions will change.
sup dimensions from 2d to 3d change

That’s why most technical 2d drawings show dimensions from the top AND from a side.
sup 2d dimensionsioning


Thank you very much for your clarifications, so there is no solution for this problems by modifying scales…

You can get a “flattened” 2D view of one roof plane at a time by selecting it, right-clicking and selecting “align view” from the context menu.


It’s not a problem, it’s geometry, and you’ll get the same results with any scale, if you want to show the real measurements of the roof you must make views from the front and top.

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If you need total precision you need to export from Sketchup, not Layout.
Layout will give you roughly the correct dimensions (99,999%) in the export, but if you crank up the dimension precision in the Autocad file you’ll find small problems all over the place.

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