topic A Projected Coordinate Systems that covers the entire Atlantic Ocean? in Map Projections Questions

A Projected Coordinate Systems that covers the entire Atlantic Ocean?

KyranGraves — Thu, 10 Jan 2019 16:23:40 GMT

Hello,

We are seeking a projection (equal area) which we will be able to use for deep sea species/habitat mapping throughout the entire Atlantic Ocean. We have tried Goodes Homolosline (Ocean) but this appears to cut off the very SE Atlantic! Lambert's Azimuthal Equal Area in ArcGIS is only available in the Polar aspect (or can this be changed using lat of origin, etc?).

Any suggestions/guidance would be greatly appreciated!

Many thanks,

Kyran

projection query‌ projection system‌ The Atlantic

Re: A Projected Coordinate Systems that covers the entire Atlantic Ocean?

BojanŠavrič — Thu, 10 Jan 2019 19:43:37 GMT

Yes, you can modify any existing projected coordinate system in ArcGIS or you can create a new one from scratch by selecting "Add Coordinate System." I hope this helps.

Re: A Projected Coordinate Systems that covers the entire Atlantic Ocean?

KyranGraves — Fri, 11 Jan 2019 09:27:58 GMT

Thank you for your reply, yes that is helpful! Will altering the settings in any way change the way the projection behaviours, or will it just change the aspect so to speak?

Please forgive me if these are relatively obvious questions/answers, still a GIS newbie!

Thanks again.

Re: A Projected Coordinate Systems that covers the entire Atlantic Ocean?

BojanŠavrič — Fri, 11 Jan 2019 18:28:26 GMT

In general, it depends on projection parameters projection has. Some can alter the overall shape of the map, some just shift coordinates, some change the aspect. In your particular example, the Lambert azimuthal equal-area projection will maintain its shape, low distortion near the center, deformations growing towards the periphery and the north will stay "up." What will change is the center of the map.

Re: A Projected Coordinate Systems that covers the entire Atlantic Ocean?

JoshuaBixby — Fri, 11 Jan 2019 22:31:49 GMT

We have tried Goodes Homolosline (Ocean) but this appears to cut off the very SE Atlantic!

I am far from a cartographer, more of a geospatial analyst, but any projection worth anything doesn't have holes or gaps in it. I haven't worked with Goodes Homolosline, but I am guessing it isn't cutting off the SE Atlantic as much as not displaying it contiguously with the rest of the Atlantic. Saying something is "cut off", to me, implies it is gone or not present at all versus not being displayed where you would like.

I think Lambert's Azimuthal Equal Area will be the way to go. I don't have a machine near me right now with ArcGIS Desktop installed, but Lambert Azimuthal Equal Area projection shows some examples where the center of the projection is changed from the poles.