topic Re: How do I get ArcGIS to rotate so that "up" is north? in Geoprocessing Questions

How do I get ArcGIS to rotate so that "up" is north?

AlexUnderwood — Tue, 15 Feb 2011 02:49:32 GMT

I am making some maps for a book. I usually use South Polar Stereographic for my maps. I want page "up" to always be north. I can get ArcMap to rotate the map using Layers->Properties->General, but then I'm just doing north by eye. It seems that there has to be some way of getting ArcGIS to rotate it so that "up" is north. Anyone know how to do this? Thank you in advance.

I'm using ArcGIS 10.

Re: How do I get ArcGIS to rotate so that "up" is north?

MichaelStead — Tue, 15 Feb 2011 04:37:50 GMT

Does the rotate data frame tool do what you want (add the data frame toolbar)

Re: How do I get ArcGIS to rotate so that "up" is north?

DonovanCameron — Tue, 15 Feb 2011 16:14:26 GMT

Are you wanting to figure out a way to determine how to rotate the map so that North is always up?

I will demonstrate on 9.3.1

There is a small formula you can use to calculate the amount of rotation needed:

get the InvTan of (YDifference / XDifference)

For instance, if I draw a line at an angle:
[ATTACH]4808[/ATTACH]

Start an edit session to get the X,Y coordinates of the corners/ends:
Feature Selected in Edit session:[ATTACH]4809[/ATTACH]
Hover over a vertex, right click and select Properties to open sketch properties window: [ATTACH]4810[/ATTACH]

Note the x,y values and get their difference: X1 - X2 and Y1 - Y2
Xdiff = 2744882.428 - 1613945.359 = 1130937.069
Ydiff = 6677341.207 - 6448747.544 = 228593.663

Press Windows Key + R and type in "calc" without the quotes and hit enter to open the calculator:
Result shown is from InvTan (228593.663 / 1130937.069)
In calculator, do the division calculation first, which should, in this case give you: 0.20212765967794093059301781538828

With that result in the window, place a checkmark beside Inv, and press the Tan button:
[ATTACH]4811[/ATTACH]

Result: 11.42710159964098606467054232324

or

rotate dataframe 11.427 degrees, or -348.573 degrees
[ATTACH]4812[/ATTACH]

Re: How do I get ArcGIS to rotate so that "up" is north?

MelitaKennedy — Tue, 15 Feb 2011 17:45:57 GMT

I am making some maps for a book. I usually use South Polar Stereographic for my maps. I want page "up" to always be north. I can get ArcMap to rotate the map using Layers->Properties->General, but then I'm just doing north by eye. It seems that there has to be some way of getting ArcGIS to rotate it so that "up" is north. Anyone know how to do this? Thank you in advance.

I'm using ArcGIS 10.

Change the central meridian of the projected coordinate system?

Re: How do I get ArcGIS to rotate so that "up" is north?

AlexUnderwood — Thu, 17 Feb 2011 00:57:37 GMT

Thanks everyone. Great suggestions (especially the idea of changing the central meridian)! Much appreciated.