Draw a line in one of the sketches for the length, width or height (it should be common to both views).
In the second sketch adjust the picture to match the length of that line.
can u please give em a example image im new on this
Make sure that the photos that you take (or have received) have no perspective in them. If you're taking them, take them from 20 feet or so away with telephoto lense to eliminate any perspective.
i think you can google imaging sdk and you will find many useful tools, or google how to scale images to get instructive articles. i have years of experience in processing images so i can give you some advices. i am using an imaging sdk which can scale images in c# and other formats ,you can have a try. good luck!
Go check out SW2014 Beta - new h enhancement in Sketch Picture you might be interested in.