Échelle de la carte et barre d'échelle

StephenKing3

Bonjour,

Je cherche des conseils. Si j'utilise WGS 1984 comme système de coordonnées de la carte, est-il approprié d'afficher une barre d'échelle et une échelle (par exemple 1:450 000) sur la carte ? D'après ce que je comprends, une barre d'échelle fixe ne serait pas appropriée car il n'est pas possible de prendre des mesures linéaires précises à partir d'une carte non projetée. Est-il donc également incorrect d'afficher une échelle ?

Merci.

HeatherSmith

@StephenKing3 I wasn't sure of the answer to this one, so I asked John Nelson, who recently wrote about a similar topic (which was possibly the inspiration for your question). Here's what he had to say:

"In Pro, the scale of a layout (so its reference scale and any scalebar you put in a layout) corresponds to the center of the map. I think the answer I would give in this case is, ‘it depends but leads towards sure.’

Some of the dependencies that come to mind:

The latitude where this person is mapping will have an impact on how inconsistent the scale would be from the top vs the bottom of the map. More extreme latitudes will amplify it. Just a quick visual spot-check in the northern USA the scale distance difference was imperceptible to my crusty eyes.

At the scale they are mapping, (1:450,000) the scale difference across the map is negligible. If it’s an engineering schematic where a map reader is actually using the scalebar to do precision planning and measurements I’d say no. But I doubt that’s the case.

They can always add a small text note next to the reference scale and scalebar on the layout indicating that the scale corresponds to the center of the map and there can be minor, probably imperceptible, differences in scale at the top and bottom of the view."