# Tip: Planetary Projections in QGIS

**URL:** <https://openplanetary.discourse.group/t/tip-planetary-projections-in-qgis/459>\
**Category:** Tools and Web Services\
**Tags:** qgis\
**Created:** [March 24, 2021, 10:21am UTC](https://openplanetary.discourse.group/t/tip-planetary-projections-in-qgis/459 "2021-03-24T10:21:17Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![swalter](https://avatars.discourse-cdn.com/v4/letter/s/cab0a1/32.png) [@swalter](https://openplanetary.discourse.group/u/swalter)\
**Post date:** [March 24, 2021, 10:21am UTC](https://openplanetary.discourse.group/t/tip-planetary-projections-in-qgis/459/1 "2021-03-24T10:21:17Z")

</div>

When using QGIS with planetary datasets in current versions (3.x), we get this or similar error messages:

> CRITICAL No transform available between SINUSOIDAL MARS and EPSG:4326  
> CRITICAL No transform available between SINUSOIDAL MARS and Custom CRS

(here we used [this](https://maps.planet.fu-berlin.de/mex4/h1104_0000.ihs.53.tif) image as an example data set)  
As a result, coordinate display in latitude and longitude is not possible, the scale bar and the measurement tools do not correctly work.  
This can be solved by providing a geographic reference system matching to our data for the QGIS project. In our example (watch out for the “truncated” Mars radius of 3396 km), we create a custom CRS in QGIS (settings-\>custom projections) with the following WKT (adapt the ellipsoid radius for your needs):

> ```
> GEOGCRS["MARS Geographic",
> DATUM["D_MARS",
> ELLIPSOID["MARS",3396000,0,
> LENGTHUNIT["metre",1,
> ID["EPSG",9001]]]],
> PRIMEM["Reference meridian",0,
> ANGLEUNIT["degree",0.0174532925199433,
> ID["EPSG",9122]]],
> CS[ellipsoidal,2],
> AXIS["longitude",east,
> ORDER[1],
> ANGLEUNIT["degree",0.0174532925199433,
> ID["EPSG",9122]]],
> AXIS["latitude",north,
> ORDER[2],
> ANGLEUNIT["degree",0.0174532925199433,
> ID["EPSG",9122]]]]
> 
> ```

Then choose it as your project’s CRS (Project-\>Properties-\>CRS) and the problems should be gone. Some similar error messages are still shown, but these can be safely ignored, they are related to some widgets in the status bar. Lat/lon values should be correct, also the scale bar and measurement should work (double check with a known-sized feature).  
More information [here](https://github.com/qgis/QGIS/issues/42378) and [here](https://lists.osgeo.org/pipermail/qgis-user/2021-March/048406.html).  
_Tested with QGIS 3.16.1 and QGIS 3.19-nightly 2021/03/23_