Aerial View Maps

Scale bar,Hi all, I have an aerial photo which needs interpretation and a proper scale.?

Hi all, I have an aerial photo which needs interpretation and a proper scale. I have done the inteepretation and done the scale, as they were required. One thing that I could not get my head around is assigning the scale bar. The scale of the aerial map is 1:80,000. How do I derive a proper sclae bar for this map? Please help, as this will save me.

Public Comments

1. The scale is very easy: if something is 1 cm on your printout, it is 80,000 cm in reality. The problem is ... where did you get the aerial photo from? Because if it is digital, you still don't know what is 1 cm. You see, the error is often done in computer graphic: People say: I want this or that in so many cm. But that's only the size, not the resolution. Others will say: I want that 2,000 pixels wide. That's the resolution but not the size! In order to know it properly, you need to know both the resolution and the size. In Desktop Publishing, the usual way to do it is to say e.g. I want this to be 20 cm at 300 dpi (dots per inch). Only then, do you know the actual scale. Once you know that, it is simply a matter to show a scale in the margin of your artwork with say, one kilometer or one mile. If you want to give the scale in latitude and longitude, you do it this way: one minute of latitude is exactly one nautical mile, i.e. 1,852 meters.One minute of longitude is the same but multiplied by the cosine of the latitude. The reason being that the longitudes narrow as the get closer to the Poles. For example, I live near Oslo, Norway, at latitude 60 north. Because cosine 60 is exactly 0.5, a minute of longitude here is half a nautical mile or 926 meters. I hope it helps. Good luck.