topic Re: Calculate distance between two projected points for given projection and scale in Python Questions

Calculate distance between two projected points for given projection and scale

MihkelMänna — Fri, 27 Oct 2017 12:50:29 GMT

Hi all,

I need to calculate the distance between two projected points - NOT the "real-world" planar/geodesic/great-elliptic distance - BUT the distance as it would appear on a paper map (in millimeters) for a given projection and map scale.

How could I do that? Any help would be really appreciated

Re: Calculate distance between two projected points for given projection and scale

DanPatterson_Retired — Fri, 27 Oct 2017 13:02:49 GMT

Pythagorean theorem ? perhaps the two points you have would be useful, since there must be more to the question than meets the eye if you have ruled out planar and geodesic shapes from the start

Re: Calculate distance between two projected points for given projection and scale

MihkelMänna — Fri, 27 Oct 2017 13:14:19 GMT

Sorry for being unclear in my initial question. My intention is to adjust the position of some text and layout elements in my Data Driven Pages mxd according to the position and size of my map. I think I need to know the planar distance between some points on the map to do this and I have to base my calculation on the points' "real-world" coordinates. Am I going in the wrong direction?

Re: Calculate distance between two projected points for given projection and scale

DanPatterson_Retired — Fri, 27 Oct 2017 13:21:26 GMT

then my initial suggestion will work. If you have the initial location and need to adjust the object (text and layout elements) you just need to know the change in X and Y associated with the move.

'Real-world coordinates' is a bit of a misnomer, since that depends on the coordinate system being used. All coordinates are 'real' in the sense that there is no single way to express them. If you have to move projected coordinates, that is simple which I suspect you probably have since no one is going to produce a map in geographic coordinates because it won't look 'real'

Re: Calculate distance between two projected points for given projection and scale

MihkelMänna — Fri, 27 Oct 2017 13:47:19 GMT

Thanks for the answers and sorry for the confusion, Dan! You're absolutely right! I realized now where I was going wrong with my initial solution! Thanks again!