[GPlates-discuss] Strange behavior reconstruction to 0 Ma

[John Cannon]

Hi Thomas,

It sounds like you're reconstructing present day raster data to past times. And that you uniformly grid your points once at present-day (rather than at each time step), then assign plate IDs once at present day (eg, using static polygons dataset), and then reconstruct them to past times.

This sounds slightly different than the raster reconstruction previously discussed on this list (where the points are uniformly gridded and assigned plate IDs at each past time, rather than present day):
https://mailman.sydney.edu.au/pipermail/gplates-discuss/2019-July/000746.html

Does that sound right?

If so, then I'm not sure how "The "original" and "reconstructed" points are still the same, but they moved off the grid".  All I can think of is a non-zero rotation at present day, or a non-zero anchor plate, when reconstructing.  But that sounds unlikely.

Regards,
John

From: GPlates-discuss <gplates-discuss-bounces at mailman.sydney.edu.au> On Behalf Of Linden, T.J.M. van der (Thomas)
Sent: Wednesday, 11 December 2019 7:29 PM
To: gplates-discuss at mailman.sydney.edu.au
Subject: [GPlates-discuss] Strange behavior reconstruction to 0 Ma

Hello,

I have been working with pygplates to reconstruct raster data. To do that I make a grid at 0.5 degree latitude-longitude and put those as points in a shape (or a gpml). These points are then reconstructed to different ages. As a habit my reconstructions start at 0 Ma and go with time steps of 10 Myr.

While looking at the "reconstruction" at 0 Ma, I noticed that the coordinates changed. The "original" and "reconstructed" points are still the same, but they moved off the grid. At other time steps the coordinates of the "original" points seem to be on the grid.
I could not find an explanation for this behavior and it seems unwanted to me.

Cheers,
Thomas
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