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Mapping Pacific centered map for Spatial analysis

4 messages · Micha Silver, Roger Bivand, sownal chand

Original
sownal chand
# 
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://www.pinterest.com/pin/740982944911004875 ) 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
crop country boundaries and shapefiles and still found lots of errors in my
codes.

Hoping to find solutions to my problems and learn from this.

yours sincerely
sownalc
Contact: sownalchand at gmail.com
PH +679 2960779
Micha Silver
#
On 13/03/2022 01:41, sownal chand wrote:
There are tons of online resources. You could, for example, refer to:

https://geocompr.robinlovelace.net/
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?

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      Roger Bivand
    

    

      
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On Sun, 13 Mar 2022, Micha Silver wrote:

        

            

      
      
      
    

        
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

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      sownal chand
    

    

      
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Hello sir(s),

Firstly I would like to thank both of you for your input in assistance me
with my problems that I am facing using R aa a spatial analysis tool.

I have been trying to do this for past 6 months and have found it really
challenging but quite interesting as well.

I will look at the codes and try to complete my project.

Sir all credits goes to both of you since you have provided timely response
to my questions.

If I do face any issues will try to consult again.

Yours sincerely
Sownal

        
On Mon, Mar 14, 2022, 02:07 Roger Bivand <Roger.Bivand at nhh.no> wrote: