Trouble creating an accurately scaled map

[michaeldthomas24 0]

hello... i'm really stuck on this problem and would appreciate any help that the community can offer. I'm trying to create a 10.2 mile by 10.2 mile accurate map of my hometown (cincinnati) but have run into a problem. I picked the 10x10 because I thought that would fit in a 1025x1025 pixel region the best... however when using global mapper i noticed that if I crop a perfect square it actually measures longer length wise than width wise on a true map. In other words... my east-west axis is ten miles long just like a i want... but my north-south axis is like 15 miles... even though on global mapper and irfan view its cropped as a perferct square!!

Why does it do this.... or what am I doing wrong to create this problem? Any feedback would be greatly appreciated!!

Thanks,
mike

[Constantina 5]

Hi,

Take a look at this article:

https://www.simtropolis.com/forum/messageview.cfm?catid=147&threadid=76310&enterthread=y

Enjoy your stay.

[MallowTheCloud 41]

Hello, Michael!

Yes, Global Mapper (to account for differences in latitude) does not have the same west-to-east scale as it does north-to-south.

Therefore, in IrfanView, after you have cropped a region, resize it to where the width is 64 times the number of km wide your cropped region is, and the length is 64 times the number of km high your cropped region is. It will no longer be square, but it will be accurately scaled.

Then, you can crop it further in IrfanView to make it square, if you like (10x10 km would be a 641x641 image, but 10x10 miles would be about a 1025x1025 image)