Created attachment 158276 [details] material for testing Open attached document. It has a green and a red square to be rotated. The layer 'layer 4' has a gray line to indicate the proposed position of the rotation axis. Mark the red square. Click on "In 3D Rotation Object" in toolbar "Transformations". You get an axis with two handles. Drag the handles to the end of the gray line. Click outside to finish creating a 3D rotation object. Notice, that you get a ring, but it is vertically compressed. Mark the green square together with the green line. Click on "In 3D Rotation Object" in toolbar "Transformations". You get an axis with two handles. Drag the handles to the end of the gray line. Click outside to finish creating a 3D rotation object. Now the height is correct. The path of the created object is a square in file format. But the automatically calculated height of the scene is wrong.
Regina Henschel committed a patch related to this issue. It has been pushed to "master": https://git.libreoffice.org/core/commit/a33484276ed16af7599a59653677f21f051c97e8 tdf#131033 consider 20° tilt of 3D in 2D projection It will be available in 7.0.0. The patch should be included in the daily builds available at https://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More information about daily builds can be found at: https://wiki.documentfoundation.org/Testing_Daily_Builds Affected users are encouraged to test the fix and report feedback.