topic Re: Custom coordinate systems - Longitudinal ranges in Mapping Questions

Custom coordinate systems - Longitudinal ranges

ChristineHomuth — Fri, 17 Mar 2017 17:29:46 GMT

I'm using the SimpleCylindrical_Titan coordinate system, which has a range of 180W to 180E.

Data for Titan (Saturn's moon) typically ranges from 0 to 360W, centering on 180.

Is there any way to alter the range of values in order to display properly from 0 to 360, rather than 180 to 180?

Thank you,

Christine

Re: Custom coordinate systems - Longitudinal ranges

JimCousins — Fri, 17 Mar 2017 19:15:55 GMT

Interesting question. I am assuming you wish to create this coordinate system for use in ArcGIS, so I am adding Melita Kennedy as a keyword here, as she will see it since it references her. She is Senior Product Engineer for Map Projections and Transformations at ESRI, and your best bet for a solution.

Best Regards,

Jim

Re: Custom coordinate systems - Longitudinal ranges

ChristineHomuth — Fri, 17 Mar 2017 19:33:58 GMT

Hi Jim and Melita,

Yes, I was trying to create a custom coordinate system. I'm able to change the central meridian (180), but not the range (0 to 360, positive west).

The coordinate system is based on SimpleCylindrical_Titan, with the following ranges and radii:

CenterLongitude = 180.0

EquatorialRadius = 2575000.0 <meters>

PolarRadius = 2575000.0 <meters>

LongitudeDirection = PositiveWest

LongitudeDomain = 360

MinimumLatitude = -90.0

MaximumLatitude = 90.0

MinimumLongitude = 0.0

MaximumLongitude = 360.0

Christine

Re: Custom coordinate systems - Longitudinal ranges

JimCousins — Fri, 17 Mar 2017 19:39:26 GMT

out of curiosity, what happens if you set the CenterLongitude = 0.0 ?

Re: Custom coordinate systems - Longitudinal ranges

MelitaKennedy — Fri, 17 Mar 2017 22:27:59 GMT

I don't know that we can do anything directly. I think it will be easier to re-georeference the data. Note the "postiveWest" for the LongitudeDirection value. You could just force the raster into 0-360 latitude/longitude that way. Or possibly georeference into a simple cylindrical system, center at 180.

Melita

Re: Custom coordinate systems - Longitudinal ranges

ChristineHomuth — Fri, 31 Mar 2017 15:12:18 GMT

Ok, thank you Melita!