# ESRI code for British National Grid not known by GeoIO
**URL:** https://discourse.julialang.org/t/esri-code-for-british-national-grid-not-known-by-geoio/117641
**Category:** Geo
**Tags:** package, geoio
**Created:** [July 30, 2024, 4:05pm UTC](https://discourse.julialang.org/t/esri-code-for-british-national-grid-not-known-by-geoio/117641 "2024-07-30T16:05:08Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@TimG](https://discourse.julialang.org/u/TimG)
#### Post date: [July 30, 2024, 4:05pm UTC](https://discourse.julialang.org/t/esri-code-for-british-national-grid-not-known-by-geoio/117641/1 "2024-07-30T16:05:08Z")
```julia
ERROR: LoadError: ArgumentError: EPSG/ESRI code for the ESRI ID "British_National_Grid" not found in dictionary.
Please check https://github.com/JuliaEarth/CoordRefSystems.jl/blob/main/src/strings.jl
If you know the EPSG/ESRI code of a given ESRI WKT string, please submit a pull request.
```
I’m reading this shape file from [here](https://geoportal.statistics.gov.uk/datasets/127c4bda06314409a1fa0df505f510e6_0/explore) at the the UK Office for National Statistics (ONS): `LAD_DEC_2023_UK_BGC.shp`.
Google tells me the British National Grid is `EPSG:27700`.
How can I circumvent this error and make the file load successfully? Alternatively, can GeoIO be made to “just work” with BNG again as it did a few weeks ago?
---
### Author:  [@nilshg](https://discourse.julialang.org/u/nilshg)
#### Post date: [July 30, 2024, 4:11pm UTC](https://discourse.julialang.org/t/esri-code-for-british-national-grid-not-known-by-geoio/117641/2 "2024-07-30T16:11:52Z")
What is the question?
---
### Author:  [@TimG](https://discourse.julialang.org/u/TimG)
#### Post date: [July 30, 2024, 4:15pm UTC](https://discourse.julialang.org/t/esri-code-for-british-national-grid-not-known-by-geoio/117641/3 "2024-07-30T16:15:11Z")
Updated OP to clarify.
---
### Author:  [@nilshg](https://discourse.julialang.org/u/nilshg)
#### Post date: [July 30, 2024, 4:22pm UTC](https://discourse.julialang.org/t/esri-code-for-british-national-grid-not-known-by-geoio/117641/4 "2024-07-30T16:22:27Z")
> [@TimG](#):
>
> How can I circumvent this error and make the file load successfully?
Looking at the code referenced in the error message, it looks like you need to submit a PR that adds `"British National Grid" => EPSG{27700}` to the `esriid2code` dictionary.
> [@TimG](#):
>
> Alternatively, can GeoIO be made to “just work” with BNG again as it did a few weeks ago?
If your issues are caused by an update of `GeoIO`, you can either `undo` that package update if you are still in the same session (see [Pkg.undo](https://pkgdocs.julialang.org/v1/api/#Pkg.undo)) or you can downgrade `GeoIO` to whichever version worked for you by requesting that version specifically, i.e. `add GeoIO@x.y` where `x.y` is the version number you want.
---
### Author:  [@juliohm](https://discourse.julialang.org/u/juliohm)
#### Post date: [July 30, 2024, 4:46pm UTC](https://discourse.julialang.org/t/esri-code-for-british-national-grid-not-known-by-geoio/117641/5 "2024-07-30T16:46:41Z")
Thank you @nilshg for the help.
> [@nilshg](#):
>
> Looking at the code referenced in the error message, it looks like you need to submit a PR that adds `"British National Grid" => EPSG{27700}` to the `esriid2code` dictionary.
That is precisely it. @TimG you need to find what is the ESRI ID in the CRS string of your file, and submit a PR pointing to the correct EPSG/ESRI code. Please let us know if you need assistance with the PR.
We are gradually updating GeoIO.jl to load CRS information stored in all these file formats. In the past it was just loading assuming a `Cartesian` CRS.
---
### Author:  [@TimG](https://discourse.julialang.org/u/TimG)
#### Post date: [July 31, 2024, 7:46am UTC](https://discourse.julialang.org/t/esri-code-for-british-national-grid-not-known-by-geoio/117641/6 "2024-07-31T07:46:46Z")
Thanks both for guidance.
Here is my pull request. I hope it’s right!
[Update strings.jl to add British\_National\_Grid by TimG1964 · Pull Request #132 · JuliaEarth/CoordRefSystems.jl (github.com)](https://github.com/JuliaEarth/CoordRefSystems.jl/pull/132)
---
### Author:  [@juliohm](https://discourse.julialang.org/u/juliohm)
#### Post date: [July 31, 2024, 9:37am UTC](https://discourse.julialang.org/t/esri-code-for-british-national-grid-not-known-by-geoio/117641/7 "2024-07-31T09:37:51Z")
Thank you! Released a patch with the addition: [New version: CoordRefSystems v0.10.3 by JuliaRegistrator · Pull Request #112095 · JuliaRegistries/General · GitHub](https://github.com/JuliaRegistries/General/pull/112095)
The next step consists of mapping the `EPSG{27700}` code you added to the corresponding type in CoordRefSystems.jl. You can do this by adding a `get` method here:
>
Please let us know if you need assistance.
---
### Author:  [@TimG](https://discourse.julialang.org/u/TimG)
#### Post date: [July 31, 2024, 9:49am UTC](https://discourse.julialang.org/t/esri-code-for-british-national-grid-not-known-by-geoio/117641/8 "2024-07-31T09:49:03Z")
Yes, please - help!
I have looked [here](https://epsg.io/27700) on the EPSG io and there is lots of information but I don’t know what to take from there or how to add it to your table.
```julia
Attributes
Unit: metre
Geodetic CRS: OSGB36
Datum: Ordnance Survey of Great Britain 1936
Ellipsoid: Airy 1830
Prime meridian: Greenwich
Data source: EPSG
Information source: Ordnance Survey of Great Britain.
Revision date: 2021-03-18
Scope: Engineering survey, topographic mapping.
Area of use: United Kingdom (UK) - offshore to boundary of UKCS within 49°45'N to 61°N and 9°W to 2°E; onshore Great Britain (England, Wales and Scotland). Isle of Man onshore.
Coordinate system: Cartesian 2D CS. Axes: easting, northing (E,N). Orientations: east, north. UoM: m.
```
---
### Author:  [@juliohm](https://discourse.julialang.org/u/juliohm)
#### Post date: [July 31, 2024, 10:29am UTC](https://discourse.julialang.org/t/esri-code-for-british-national-grid-not-known-by-geoio/117641/9 "2024-07-31T10:29:40Z")
Of course! Let me share some resources here to help you and also help future contributors.
If you know the EPSG code, you can use [epsg.org](http://epsg.org)’s search engine to find a more organized set of parameters for your CRS: [https://epsg.org/search/by-name](https://epsg.org/search/by-name)
In this case, I searched for `27700` and found your CRS in the CRSs tab:
By clicking on it, you will be directed to the following page:
The first information you need to find is the datum of the CRS. If you start clicking on the links, you will find a datum entry:
In this case the datum is called “Ordnance Survey of Great Britain 1936” or “OSGB36” for short. This is already available in CoordRefSystems.jl as you can see here:
>
The next information you need is the coordinate system, which is also there:
It says that you are dealing with `Cartesian2D` coordinates in `m` units. This is also available in CoordRefSystems.jl as you can see here:
>
Now you can construct the full CRS type for your EPSG code:
```julia
get(::Type{EPSG{27700}}) = Cartesian2D{OSGB36}
```
Can you submit a PR with this code added, and a test for coverage?
### Note
There is a final missing feature in CoordRefSystems.jl to fully handle local grids (e.g. British grid) in conversions. This means that conversions from EPSG{27700} to other CRS may be slightly off. We are planning to add this feature in the following months.
---
### Author:  [@TimG](https://discourse.julialang.org/u/TimG)
#### Post date: [July 31, 2024, 10:32am UTC](https://discourse.julialang.org/t/esri-code-for-british-national-grid-not-known-by-geoio/117641/10 "2024-07-31T10:32:35Z")
Thank you. I’d never have figured this out alone!
> [@juliohm](#):
>
> and a test for coverage?
I’m afraid I’ll need a bit more help with this, too.
---
### Author:  [@juliohm](https://discourse.julialang.org/u/juliohm)
#### Post date: [July 31, 2024, 10:41am UTC](https://discourse.julialang.org/t/esri-code-for-british-national-grid-not-known-by-geoio/117641/11 "2024-07-31T10:41:15Z")
Of course, you just need to add a test here besides the other ones:
>
---
### Author:  [@TimG](https://discourse.julialang.org/u/TimG)
#### Post date: [July 31, 2024, 10:43am UTC](https://discourse.julialang.org/t/esri-code-for-british-national-grid-not-known-by-geoio/117641/12 "2024-07-31T10:43:25Z")
So just added this:
`@test CoordRefSystems.get(::Type{EPSG{227700}}) === Cartesian2D{OSGB36}`
---
### Author:  [@TimG](https://discourse.julialang.org/u/TimG)
#### Post date: [July 31, 2024, 10:50am UTC](https://discourse.julialang.org/t/esri-code-for-british-national-grid-not-known-by-geoio/117641/13 "2024-07-31T10:50:59Z")
I’ve made a new PR but it is against the clone I took earlier this morning which you’ve now changed. Presumably this’ll still work, though.
[Updated get.jl and relevant test for EPSG:27700 (British National Grid) by TimG1964 · Pull Request #133 · JuliaEarth/CoordRefSystems.jl (github.com)](https://github.com/JuliaEarth/CoordRefSystems.jl/pull/133)
---
### Author:  [@juliohm](https://discourse.julialang.org/u/juliohm)
#### Post date: [July 31, 2024, 11:00am UTC](https://discourse.julialang.org/t/esri-code-for-british-national-grid-not-known-by-geoio/117641/14 "2024-07-31T11:00:45Z")
I commented on the PR. We sorted the lines of the dictionary alphabetically and that caused conflicts with your new changes. Do you know how to fix git conflicts? You can click on the “Resolve conflicts” and retain only the newly added lines in get.jl and test / get.jl
---
### Author:  [@juliohm](https://discourse.julialang.org/u/juliohm)
#### Post date: [July 31, 2024, 11:44am UTC](https://discourse.julialang.org/t/esri-code-for-british-national-grid-not-known-by-geoio/117641/15 "2024-07-31T11:44:29Z")
@TimG a small correction regarding the type. In the current design we need to use the type that corresponds to the conversion method:
In this case, this is:
```julia
TM = TransverseMercator{0.9996012717,49°,-2°,OSGB36}
get(::EPSG{27700}) = shift(TM, xₒ=400000m, yₒ=-100000m)
```
Given that this is much more verbose, we will take care of it for you.
Will let you know here when the patch is released.
---
### Author:  [@TimG](https://discourse.julialang.org/u/TimG)
#### Post date: [July 31, 2024, 11:57am UTC](https://discourse.julialang.org/t/esri-code-for-british-national-grid-not-known-by-geoio/117641/16 "2024-07-31T11:57:59Z")
> [@juliohm](#):
>
> I commented on the PR.
I just resubmitted my PR as suggested and then came back to read your latest.
Thank you for taking over!
---
### Author:  [@nilshg](https://discourse.julialang.org/u/nilshg)
#### Post date: [July 31, 2024, 12:46pm UTC](https://discourse.julialang.org/t/esri-code-for-british-national-grid-not-known-by-geoio/117641/17 "2024-07-31T12:46:16Z")
Might be useful to put this somewhere in the docs and link to that in the error message rather than straight to the code as you currently do? Granted I’m not a geoscientist, but I don’t think I would have ever figured out to do all these things from the error message…
---
### Author:  [@juliohm](https://discourse.julialang.org/u/juliohm)
#### Post date: [July 31, 2024, 12:55pm UTC](https://discourse.julialang.org/t/esri-code-for-british-national-grid-not-known-by-geoio/117641/18 "2024-07-31T12:55:56Z")
It is in our TODO list. Maybe a link to this discourse thread would already help in the meantime?
---
### Author:  [@juliohm](https://discourse.julialang.org/u/juliohm)
#### Post date: [July 31, 2024, 1:05pm UTC](https://discourse.julialang.org/t/esri-code-for-british-national-grid-not-known-by-geoio/117641/19 "2024-07-31T13:05:32Z")
@TimG new patch released:
>
>
> \- Registering package: CoordRefSystems
> \- Repository: https://github.com/JuliaEar…th/CoordRefSystems.jl
> \- Created by: @juliohm
> \- Version: v0.10.4
> \- Commit: 1eb518ca50881db8203c660f77ec045f868a1ed3
> \- Reviewed by: @juliohm
> \- Reference: https://github.com/JuliaEarth/CoordRefSystems.jl/commit/1eb518ca50881db8203c660f77ec045f868a1ed3#commitcomment-144854404
> \- Description: Unitful coordinate reference systems for geographic maps in Julia
Please let us know if you are still unable to load the shapefile with correct CRS.
---
### Author:  [@TimG](https://discourse.julialang.org/u/TimG)
#### Post date: [July 31, 2024, 1:25pm UTC](https://discourse.julialang.org/t/esri-code-for-british-national-grid-not-known-by-geoio/117641/20 "2024-07-31T13:25:42Z")
Thank you for turning this round so quickly.
However:
```julia
ERROR: LoadError: MethodError: no method matching topoint(::Shapefile.Point, ::Type{CoordRefSystems.ShiftedCRS{CoordRefSystems.TransverseMercator{0.9996012717, Quantity{Float64, Unitful.Dimensions{()}(), Unitful.FreeUnits{(Unitful.Unit{:Degree, Unitful.Dimensions{()}()}(0, 1//1),), Unitful.Dimensions{()}(), nothing}}(49.0), Quantity{Float64, Unitful.Dimensions{()}(), Unitful.FreeUnits{(Unitful.Unit{:Degree, Unitful.Dimensions{()}()}(0, 1//1),), Unitful.Dimensions{()}(), nothing}}(-2.0), OSGB36}, Quantity{Float64, Unitful.Dimensions{()}(), Unitful.FreeUnits{(Unitful.Unit{:Degree, Unitful.Dimensions{()}()}(0, 1//1),), Unitful.Dimensions{()}(), nothing}}(0.0), Quantity{Float64, Unitful.Dimensions{(Unitful.Dimension{:Length}(1//1),)}(), Unitful.FreeUnits{(Unitful.Unit{:Meter, Unitful.Dimensions{(Unitful.Dimension{:Length}(1//1),)}()}(0, 1//1),), Unitful.Dimensions{(Unitful.Dimension{:Length}(1//1),)}(), nothing}}(400000.0), Quantity{Float64, Unitful.Dimensions{(Unitful.Dimension{:Length}(1//1),)}(), Unitful.FreeUnits{(Unitful.Unit{:Meter, Unitful.Dimensions{(Unitful.Dimension{:Length}(1//1),)}()}(0, 1//1),), Unitful.Dimensions{(Unitful.Dimension{:Length}(1//1),)}(), nothing}}(-100000.0)}})
Closest candidates are:
topoint(::Any, ::Type{<:GeodeticLatLon{Datum}}) where Datum
@ GeoIO C:\Users\TGebbels\.julia\packages\GeoIO\V1sFL\src\conversion.jl:62
topoint(::Any, ::Type{<:Cartesian3D{Datum}}) where Datum
@ GeoIO C:\Users\TGebbels\.julia\packages\GeoIO\V1sFL\src\conversion.jl:60
topoint(::Any, ::Type{<:Cartesian2D{Datum}}) where Datum
@ GeoIO C:\Users\TGebbels\.julia\packages\GeoIO\V1sFL\src\conversion.jl:58
Stacktrace:
[1] (::GeoIO.var"#8#9"{UnionAll})(p::Shapefile.Point)
@ GeoIO .\none:0
[2] iterate
@ .\generator.jl:47 [inlined]
[3] collect(itr::Base.Generator{Base.Generator{UnitRange{Int64}, GeoInterface.var"#22#23"{GeoInterface.LinearRingTrait, Shapefile.LinearRing{Shapefile.Point, Nothing, Nothing}}}, GeoIO.var"#8#9"{UnionAll}})
@ Base .\array.jl:834
[4] topoints(geom::Shapefile.LinearRing{Shapefile.Point, Nothing, Nothing}, CRS::Type)
@ GeoIO C:\Users\TGebbels\.julia\packages\GeoIO\V1sFL\src\conversion.jl:64
[5] tochain(geom::Shapefile.LinearRing{Shapefile.Point, Nothing, Nothing}, CRS::Type)
@ GeoIO C:\Users\TGebbels\.julia\packages\GeoIO\V1sFL\src\conversion.jl:67
[6] (::GeoIO.var"#toring#10"{UnionAll})(g::Shapefile.LinearRing{Shapefile.Point, Nothing, Nothing})
@ GeoIO C:\Users\TGebbels\.julia\packages\GeoIO\V1sFL\src\conversion.jl:81
[7] topolygon(geom::Shapefile.SubPolygon{Shapefile.LinearRing{Shapefile.Point, Nothing, Nothing}}, CRS::Type)
@ GeoIO C:\Users\TGebbels\.julia\packages\GeoIO\V1sFL\src\conversion.jl:82
[8] #13
@ .\essentials.jl:0 [inlined]
[9] iterate
@ .\generator.jl:47 [inlined]
[10] collect(itr::Base.Generator{Vector{Shapefile.SubPolygon{Shapefile.LinearRing{Shapefile.Point, Nothing, Nothing}}}, GeoIO.var"#13#14"{UnionAll}})
@ Base .\array.jl:834
[11] togeometry(::GeoInterface.MultiPolygonTrait, geom::Shapefile.Polygon, crs::GeoFormatTypes.ESRIWellKnownText{GeoFormatTypes.CRS})
@ GeoIO C:\Users\TGebbels\.julia\packages\GeoIO\V1sFL\src\conversion.jl:108
[12] geom2meshes
@ C:\Users\TGebbels\.julia\packages\GeoIO\V1sFL\src\conversion.jl:112 [inlined]
[13] geom2meshes
@ C:\Users\TGebbels\.julia\packages\GeoIO\V1sFL\src\conversion.jl:111 [inlined]
[14] _broadcast_getindex_evalf
@ .\broadcast.jl:709 [inlined]
[15] _broadcast_getindex
@ .\broadcast.jl:682 [inlined]
[16] getindex
@ .\broadcast.jl:636 [inlined]
[17] copy
@ .\broadcast.jl:942 [inlined]
[18] materialize(bc::Base.Broadcast.Broadcasted{Base.Broadcast.DefaultArrayStyle{1}, Nothing, typeof(GeoIO.geom2meshes), Tuple{Vector{Union{Missing, Shapefile.Polygon}}, Base.RefValue{GeoFormatTypes.ESRIWellKnownText{GeoFormatTypes.CRS}}}})
@ Base.Broadcast .\broadcast.jl:903
[19] asgeotable(table::Shapefile.Table{Union{Missing, Shapefile.Polygon}})
@ GeoIO C:\Users\TGebbels\.julia\packages\GeoIO\V1sFL\src\utils.jl:13
[20] load(fname::String; repair::Bool, layer::Int64, kwargs::@Kwargs{})
@ GeoIO C:\Users\TGebbels\.julia\packages\GeoIO\V1sFL\src\load.jl:101
[21] load
@ C:\Users\TGebbels\.julia\packages\GeoIO\V1sFL\src\load.jl:26 [inlined]
[22] macro expansion
@ .\timing.jl:279 [inlined]
[23] main()
@ Main c:\Users\TGebbels\OneDrive - The National Lottery Community Fund\Documents\DCMS Database\CityMaps\GeoStat City Maps.jl:166
[24] top-level scope
@ c:\Users\TGebbels\OneDrive - The National Lottery Community Fund\Documents\DCMS Database\CityMaps\GeoStat City Maps.jl:206
[25] include(fname::String)
@ Base.MainInclude .\client.jl:489
[26] run(debug_session::VSCodeDebugger.DebugAdapter.DebugSession, error_handler::VSCodeDebugger.var"#3#4"{String})
@ VSCodeDebugger.DebugAdapter c:\Users\TGebbels\.vscode\extensions\julialang.language-julia-1.105.2\scripts\packages\DebugAdapter\src\packagedef.jl:126
[27] startdebugger()
@ VSCodeDebugger c:\Users\TGebbels\.vscode\extensions\julialang.language-julia-1.105.2\scripts\packages\VSCodeDebugger\src\VSCodeDebugger.jl:45
[28] top-level scope
@ c:\Users\TGebbels\.vscode\extensions\julialang.language-julia-1.105.2\scripts\debugger\run_debugger.jl:12
[29] include(mod::Module, _path::String)
@ Base .\Base.jl:495
[30] exec_options(opts::Base.JLOptions)
@ Base .\client.jl:318
[31] _start()
@ Base .\client.jl:552
in expression starting at c:\Users\TGebbels\...\Documents\DCMS Database\CityMaps\GeoStat City Maps.jl:206
```
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