Indesign relinking alters size of images

If you are importing PDFs of AutoCAD drawings into Indesign to say create a presentation and you update one of the drawings that has been scaled to fit in a frame and is exactly the size you want it to be and then you relink and run into the following problem.

AutoCAD drawing is the same scale 1:1. The plot is the same size and the plot scale is the same size but when re-linking the drawing you find Indesign has unhelpfully resized the image to a random size. This is probably really useful if you do a lot of swapping the same images around at different resolutions but not helpful in this case.

Here you need to change the preferences.Go to file handling and deselect preserve image dimensions when reloading. Thank you David Blatner.