Map scales and scaling images

[mabramov]

Hi,

Slowly getting to grips with Autocad 2013 which I am using mainly for drawings showing site layouts which include base map backgrounds.

Having some issues with scaling objects and understanding the significance of map scale when creating a dwg.............bit long winded, but here it is:

1. Have an existing pdf figure showing a series of square outlines superimposed on a basemap. I want to recreate this, as the quality isnt very good.

2. I inserted the pdf into autocad and traced around the square using PLINE. Then inserted a better basemap sourced from a mapping website and laid the polyline overlay over it. Used SCALE to adjust the overlay size so that it was correctly oriented on the basemap.

3. The basemap was 1:50,000 and then learnt that I must use 1:20,000. Used a gvt mapping werbsite to generate a suitable 1:20,000 basemap. Can export this as pdf, JPEG, TIFF, GeoTIFF, BMP. Selected pdf and printed the map using the export function.

4. Used SCALE in autocad to shrink the image to fit on my 11x17 dwg.

5. Laid the square outline overlay over the new base map and no amount of fiddling with SCALE could get it to correctly orient on the map..........................................what am I missing??

Final and related quation relates to specifying the scale of an image (e.g. map) when inserting it into a dwg. Is this a must do on every occasion, or only of importance if you will be measuring distances on the map using autocad?

I can probably get the coordinates of the square outline overlay as this represents surveyed areas. If I know the coordinates of each corner of the square, is there a painless way in autocad of then inserting these into a dwg as dots?

Many thanks in advance for any help!!