Mapping Pacific centered map for Spatial analysis
On Sun, 13 Mar 2022, Micha Silver wrote:
On 13/03/2022 01:41, sownal chand wrote:
Hello Sir/Madam, I am Sownal Chand, from Fiji Islands and am currently working on a project which involves spatial analysis of climate data (Temperature, rainfall, etc). I have been able to write codes in R for Point interpolations of these parameters but I require some assistance in mapping these raster files on the southwest pacific maps. For example, a map of Fiji Islands ( https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.pinterest.com%2Fpin%2F740982944911004875&data=04%7C01%7CRoger.Bivand%40nhh.no%7C3d492fafcd7247d2090e08da04cde59b%7C33a15b2f849941998d56f20b5aa91af2%7C0%7C0%7C637827580063300234%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=5xNJDee6Glb%2FW7MCkO8biDzHl1%2Bv5hc%2FBsU%2FmO9neLE%3D&reserved=0 ) and I am facing some difficulties in making these plots. I hope that some expert would be willing to help me with this and the map's CRS setting is a bit confusing and I am a beginner in this area ( i. e, spatial analysis using R). I have been looking at tutorials and codes to
There are tons of online resources. You could, for example, refer to: https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgeocompr.robinlovelace.net%2F&data=04%7C01%7CRoger.Bivand%40nhh.no%7C3d492fafcd7247d2090e08da04cde59b%7C33a15b2f849941998d56f20b5aa91af2%7C0%7C0%7C637827580063300234%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=08BU9QbKjLNh5TkKeu38etqzU%2FOysx7fqsGoVq3kImw%3D&reserved=0
crop country boundaries and shapefiles and still found lots of errors in my codes.
You have raised a few different questions. Would you mind to post what you have done so far, and point out the errors and difficulties?
It does also seem possible that the problems are initially caused by using geographical (spherical) coordinates rather than projected coordinates. Projection of the input points to say EPSG:3460, or for the broader Pacific Basin EPSG:3832, may be helpful. See https://www.asprs.org/wp-content/uploads/2012/05/10-2000-fiji.pdf for the then (publication 2000) valid description of why EPSG only seems to record Fiji with 1956 (international ellipsoid) and 1986 (WGS1972 ellipsoid). EPSG:4326 can be transformed to EPSG:3460 with 2m accuracy. Using then a projected planar extent in the local grid, the problem of crossing 180 degrees is removed. In addition, the interpolation will use metres not degrees as the metric of the positions of the points and grid cells. The planar representation should also remove plotting problems. Hope this helps, Roger
Hoping to find solutions to my problems and learn from this. yours sincerely sownalc Contact: sownalchand at gmail.com PH +679 2960779 [[alternative HTML version deleted]]
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Roger Bivand Emeritus Professor Department of Economics, Norwegian School of Economics, Postboks 3490 Ytre Sandviken, 5045 Bergen, Norway. e-mail: Roger.Bivand at nhh.no https://orcid.org/0000-0003-2392-6140 https://scholar.google.no/citations?user=AWeghB0AAAAJ&hl=en