Issue with GMT surface losing geo-referencing

Q&A
1

Hi, new to GMT so hopefully the issue here is straightforward. I have a table of xyz data and I’m trying to turn it into a surface. However, when I use surface (or xyz2grid) and increase the resolution above a certain amount the resulting surface loses its geo-referencing. I can’t find any threads regarding this issue, so any help would be greatly appreciated. Some pics of the issue and code below:

West=-80
East=15.5
South=-12
North=78

REGION=$West/$East/$South/$North
echo "Region: " $REGION
 
#Map Projection(Lat/Lon/Par1/Par2/Scale) -JB-35/90/0.5/59/15
 
Lat=-35
Lon=90
Par_1=0.5
Par_2=59
Scale=15
 
SCALE=B$Lat/$Lon/$Par_1/$Par_2/$Scale
echo "Scale: " $SCALE
 
echo 'Progress : GMT Georeferencing...'
# Georefs the .xy file using GMT
gmt mapproject thickness_with_nulls.csv -R$REGION -J$SCALE  -I \
| gmt blockmean Atlantic_Thickness.Trimmed.csv -I100k -R$REGION > blockmean_thickness_nulls.xyz
 
# Creates a grid of the above trimmed and deleted data points. 
gmt surface Atlantic_Thickness_Points.csv -I100k -R$REGION -GAtlantic_Grid

~ -I100k the gridding works well and the geo-referencing is correct, below ~ I70k it spins as shown.

Cheers

!

High res doesnt work
High res doesnt work876×620 124 KB
Low res works correctly
Low res works correctly876×620 124 KB

2

Sorry, your question is very confuse and I doubt you’ll get any valuable help. There is no code for the presented images.

Please keep in mind (or better, see the docs) that xyz2grd is not an interpolater (like surface). And you don’t need (though you can) to re-project data before gridding. But if you do, then -R must be provided in projected coordinates.