Scaling Factor


I often work on and convert small page sized drawings, and once per
year then go to very large sized plans in the 36 inch by 48 inch size
range and larger. Most all of my drawings are noted as being based in
inches. Upon begining the processing of a TIF or a BMP image, the
resulting linework then becomes very-very large in measurement. Once
processing is done on the very large sized images, I then need to
reduce the DXF file by a factor usually of around .006 to get back to
original (measured) size.

I have tried using one size factor on a whole project, but find that
factor varies depending upon day of commencement, and overall size of
the scanning. Most often the factor is different each time then.
Sometimes .0056 is good on a big drawing, then on yet another it may
be .004 for that project.

How do I determine a scale factor to apply to the import of the next
set of lines into CAD without guessing and measuring the results?

Using the new WinTopo version 1.66 at this minute but as of end of May
should have installed the Professional version.



Wm.