[Qgis-user] Mars projection

[贾博钧]

Hi Lester,


I think you can setup another custom projection:


GEOGCS["GCS_Mars_2000",DATUM["Mars_2000",
SPHEROID["Mars_2000_IAU_IAG",3396190.0,169.8944472236118]],PRIMEM["Reference_Meridian",0.0],
UNIT["Degree",0.0174532925199433]]


and this geographic CRS may already exist in qgis predefined CRSs.


Then you can set your projected CRS as project crs, and set geographic CRS above in layout (choose "Map x" item, add a new grid to "Grids" in item properties, click "Modify Grid", set geographic CRS as grid CRS in "Appearance" properties group, then set proper intervals).


Regards,



Bojun Jia





------------------ Original ------------------
From:                                                                                                                        "Lester Anderson"                                                                                    <arctica1963 at gmail.com>;
Date: Fri, Nov 19, 2021 08:00 PM
To: "qgis-user"<qgis-user at lists.osgeo.org>;

Subject: [Qgis-user] Mars projection



Hello,

I am trying to setup a custom projection for Mars using the WKT:

PROJCS["Mars_Equidistant_Cylindrical", GEOGCS["Mars 2000", DATUM["D_Mars_2000", SPHEROID["Mars_2000_IAU_IAG",3396190.0,169.89444722361179]], PRIMEM["Greenwich",0], UNIT["Decimal_Degree",0.0174532925199433]], PROJECTION["Equidistant_Cylindrical"], PARAMETER["False_Easting",0], PARAMETER["False_Northing",0], PARAMETER["Central_Meridian",0], PARAMETER["Standard_Parallel_1",0], UNIT["Meter",1]]



This is all fine and it validates ok.


What I need is to be able to use the Mars projection and be able to overlay Longitude Latitude grid lines in layout, but I get no valid transform for the default WGS84 etc. Anyone sorted out how this works?

Thanks


Lester
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