[GRASS-stats] getLocationProj - writeVECT projection check mismatch

[Roger Bivand]

On Sun, 12 Aug 2018, Paulo van Breugel wrote:

> Dear devs,
>
> The function getLocationProj returns an spproj-compliant PROJ.4 string of 
> projection information (using internally /g.proj -jf/). However, when writing 
> a vector layer to the grass database using the writeVECT function, it 
> (expects the projection information in the format returned by /g.proj -g/ 
> (checking the code, this is because it uses v.in.ogr I guess).
>
> For example, if running R from within a grass session with the NC location: I 
> have a vector layer "klatifolia" in latlong which I project it to match the 
> projection of the NC location. Next, I write it to the grass database using 
> writeVECT:
>
> proj <- getLocationProj()
> KLnew <- spTransform(KL, proj)
> writeVECT(SDF=KLnew[,c(1,2,5)], vname="KLatifolia", driver="SQLite")
>
> This results in an error telling that the projection of dataset does not 
> appear to match current location.
>
>        Location PROJ_INFO is:
>        name: Lambert Conformal Conic
>        proj: lcc
>        datum: nad83
>        a: 6378137.0
>        es: 0.006694380022900787
>        lat_1: 36.16666666666666
>        lat_2: 34.33333333333334
>        lat_0: 33.75
>        lon_0: -79
>        x_0: 609601.22
>        y_0: 0
>        no_defs: defined
>
>        Dataset PROJ_INFO is:
>        name: unnamed
>        ellps: grs80
>        proj: lcc
>        lat_1: 36.16666666666666
>        lat_2: 34.33333333333334
>        lat_0: 33.75
>        lon_0: -79
>        x_0: 609601.22
>        y_0: 0
>        towgs84: 0,0,0,0,0,0,0
>        no_defs: defined
>
>        ERROR: datum
>
> I can obviously run writeVECT with v.in.ogr_flags="o", but is there a way 
> that writeVECT can check against the spproj-compliant proj.4 string? Or is 
> this something that should be dealt with at the v.in.ogr side?

Short answer - after inspecting the two, and checking that they are the 
same, use v.in.ogr_flags="o".

Long answer: the PROJ migration from 4.* to 5.* and further is shifting 
things everywhere, so handling in GRASS and sf/rgdal will also change. On 
the R side, we are waiting for the GDAL barn-raising project (writing C++ 
classes for PROJ) to complete before considering moving to the pipeline 
model and possible new representations.

Roger

>
> Best wishes,
>
> Paulo
>
>
> sessionInfo()
> R version 3.4.4 (2018-03-15)
> Platform: x86_64-pc-linux-gnu (64-bit)
> Running under: Ubuntu 18.04.1 LTS
>
> Matrix products: default
> BLAS: /usr/lib/x86_64-linux-gnu/blas/libblas.so.3.7.1
> LAPACK: /usr/lib/x86_64-linux-gnu/lapack/liblapack.so.3.7.1
>
> locale:
>  [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C LC_TIME=en_US.UTF-8
>  [4] LC_COLLATE=en_US.UTF-8     LC_MONETARY=en_US.UTF-8 
> LC_MESSAGES=en_US.UTF-8
>  [7] LC_PAPER=en_US.UTF-8       LC_NAME=C LC_ADDRESS=C
> [10] LC_TELEPHONE=C             LC_MEASUREMENT=en_US.UTF-8 
> LC_IDENTIFICATION=C
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods base
>
> other attached packages:
> [1] ggplot2_3.0.0  mapr_0.4.0     raster_2.6-7   rgrass7_0.1-11 
> XML_3.98-1.12  maptools_0.9-3
> [7] sp_1.3-1       rgbif_1.0.2
>
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>

-- 
Roger Bivand
Department of Economics, Norwegian School of Economics,
Helleveien 30, N-5045 Bergen, Norway.
voice: +47 55 95 93 55; e-mail: Roger.Bivand at nhh.no
http://orcid.org/0000-0003-2392-6140
https://scholar.google.no/citations?user=AWeghB0AAAAJ&hl=en