Absolutely. It is ridiculous that an image with a known DPI, in any multitude of formats, cannot be inserted accurately as a canvas in fusion 360. This whole business of "scale by measurement" is completely missing the point. The files contain information and fusion is failing to use it.
Having said that, one technique is to scale the WHOLE canvas to a known size. For instance, I made a 300 dpi scan at 8.5x11". As expected, that resulted in an image which was 2550x3300 pixels, which is EXACTLY 215.9 x 279.4 mm.
Trying to understand fusion, and come up with a "standard scaling factor" for this "canvas", I did the following to achieve "pretty good" results.
(1) Import the canvas. Don't scale it.
(2) Use "calibrate" the canvas using the red outline it presents. I zoomed in as much as fusion would let me on the upper left hand corner and placed my first calibration point such that the cross-hairs were as closely aligned with the red outline as possible. Then zoom in on the upper right hand corner as much as possible and place the second calibration point. When then asked for the calibration distance, I typed in "8.5 in" (and/or had the document units in inches to begin with).
For verification, the best I have been able to do is then create a sketch on the same plane, zoom in as much as possible, and draw a line between those same two points. Add a sketch dimension to it to see what fusion thinks is the length. It showed 215.90 ... then click on the dimension itself to see the "deeper" fusion real number for which I obtained 215.900405 mm. So that put me within 1 micron.
The other approach I took was to try to come with said "standard scaling factor". By doing a series of canvas imports with different constant scaling factors, I narrowed in on something like a factor of 12.33717 which gave me the same "best effort" measurement of 215.900405 mm.
I don't know if that "factor" is the same for different drawings, different formats, or anything more than that. Why the conversion from "300dpi" requires a scaling factor of 12.33717 doesn't really make sense to me. I am trying to think of why that particular number and how fusion is working under the hood, but I shouldn't have to.
The photo is EXACTLY 300dpi and represents EXACTLY 215.9 x 279.4 ... and fusion should just know that.
Fusion
