Hello.
I’m new to GPlates and this is probably a basic question, but I couldn’t find it in the forums I’ve searched.
I did a reconstruction for 183 Ma and decided to export the shapefile and do some adjustments in ArcGis.
However, I would also like to have the shapefiles with adjustments in “present time”. In other words, I am trying to put the reconstructed shape that I edited back into Gplates and get it back to the present day position.
I am not getting the result I would like. Could someone help me?
Also, I would like an indication of some material for beginners in the software.
Thanks,
Mateus
Hi Mateus,
You might need to use pyGPlates for this. GPlates generally relies of input data being in present day coordinates.
Although one exception is assigning plate IDs (see the Features > Assign Plate Ids menu) where you could (after loading your 183Ma exported and ArcGIS-edited shapefiles) specify 183Ma as the reconstruction time (in the Assign Plate Ids dialog) and it’ll assign plate IDs to your geometries and reverse reconstruct them from 183Ma back to present day. You’ll also need to load a rotation file and static polygons first (used to assign plate IDs).
Using pyGPlates might be slightly better though, because the above approach will assign plate IDs, but you already have plate IDs for your geometries (from when you first reconstructed your Shapefiles for export). For that reason, with the above approach using GPlates, you’ll probably want the Copy feature properties from the polygon that most overlaps a feature option so that it doesn’t further partition (cut-out) your geometries using the static polygons (but it will still overwrite your existing plate IDs). Especially since you’ve changed their shape in ArcGIS.
With pyGPlates you can use your already-assigned plate IDs, from when you first reconstructed your Shapefiles for export, to reverse reconstruct them. Also, this approach only requires the rotations (not static polygons). Something like this…
import pygplates
pygplates.reverse_reconstruct('shapefile.shp', 'rotations.rot', 183)
You can try the GPlates tutorials.