In Cisco DNA when you upload a Floor under Area menu you can choose default scaling options per image (width, length, height).
But what if you do not know the default image scale? In this case, there is an option to manually measure a certain distance between known points within the floor and based on that re-scale the image.
Once the image is imported, go to Floor level, select the 3 dots in the upper right corner and select Set Scale
This will ask you to measure the distance between 2 known points on the floor.
Click, release and drag the ruler between the 2 points and it will show the proposed distance.
A window will pop up on the side presenting an option to modify the distance. Change it to the actual measure and click Ok.
That’s it. Now you have properly scaled image and you can apply heat map and more accurate location service from CMX.