Posted by perepujal on Mar 11, 2024; 7:48pm
URL: https://forum.librecad.org/Scaling-with-reference-DIM-tp5724417p5724427.html

Hi,

jlackie wrote

-The energy modeling software that I'm using (IES VE) requires an obnoxious level of precision within its 3D modeling application; approx. scaling factors (like from a CAD software rounding a dimension in the thousandth decimal place) can cause headaches later on in the energy modeling process.

See in Options -> Current Drawing Preferences -> Units if the precision you need fits in one of the offered by Librecad.
Also check Options -> Application preferences -> Defaults for the units

I need to scale a .dxf of an unknown scale to a known one. ie. CAD allows you to scale to a reference dimension. So, if I have a floor plan I that calls out a 20' dimension I can do the following in AutoCAD:
 -> draw a line that is 20'
 -> use the scale reference command (with the drawing elements selected)
 -> select the unscaled 20' dimension from the drawing
 -> then select the end points of the 20' line I drew

What I'd do with the tools I know in LC:
Mesure the line that should be scaled to 20, supposing it currently measures 100
Select all  the entities to be scaled (drag left with a green rectangle selects anything the rectangle touches, dragging right with a blue rectangle selects anything that is fully inside the rectangle, same as Autocad)
Tools -> Modify -> Scale,
Specify reference point, is not important for the matter currently.
write in the popup box 20/100 which is the measure that should have the drawing / the measure it currently has
Hit Enter

Re-measure the line and check if all has been scaled right, specially check the precision.

HTH
Pere