# OVCCoordenadas Web Service

#### Ángel Delgado Panadero

#### Diego Hernangómez

CatastRo allows to query the OVCCoordenadas Web Service provided on Sede electrónica del Catastro API directly through a R IDE.

This API is used to retrieve the spatial coordinates of a urban property, moreover it is not needed to be the owner to get the information, actually it is enough to know the cadastral reference (RC) of the property and its address (in fact, it is only completely compulsory to know the RC, however, to ensure a good result from the response and to avoid mistakes in the RC, the address can be passed to the query too).

Secondly, the API can be used to obtain a RC of a urban property, for this information, the API asks for the longitude and the latitude. Furthermore, it allows to choose the spacial reference system (SRS, also known as CRS) between a list of them to express the coordinates.

Finally, the API tackles the issue of not knowing the exact point which the urban property has been registered. In this case, it will return all the properties located in a square 50-meters-side around the given point.

The documentation of this API can be found here.

These functions are named `catr_ovc_*` and returns a `tibble`, as provided by the package tibble.

## CatastRo API

The OVCCoordenadas Web Service can be reached using the following functions:

- `catr_ovc_get_rccoor()`
- `catr_ovc_get_rccoor_distancia()`
- `catr_ovc_get_cpmrc()`

## Reverse Geocoding Cadastral References

The function `catr_ovc_get_rccoor()` receives the coordinates (`lat` and `lon`) and the spatial reference system (`srs`) used to express them. The return is a `tibble` with the cadastral reference of the property in that spatial point, including also other information as the address (town street and number).

    result <- catr_ovc_get_rccoor(
      lat = 38.6196566583596,
      lon = -3.45624183836806,
      srs = "4230"
    )

refcat | address | pc.pc1 | pc.pc2 | geo.xcen | geo.ycen | geo.srs | ldt
--- | --- | --- | --- | --- | --- | --- | ---
13077A01800039 | DS DISEMINADO Polígono 18 Parcela 39 000100200VH67C EL TIRADERO. SANTA CRUZ DE MUDELA (CIUDAD REAL) | 13077A0 | 1800039 | -3.456242 | 38.61966 | EPSG:4230 | DS DISEMINADO Polígono 18 Parcela 39 000100200VH67C EL TIRADERO. SANTA CRUZ DE MUDELA (CIUDAD REAL)

The function accept as a `srs` argument the following values:

    data(catr_srs_values)

    # OVC valid codes
    library(dplyr)

    catr_srs_values %>%
      filter(ovc_service == TRUE) %>%
      select(SRS, Description) %>%
      knitr::kable()

SRS | Description
--- | ---
4230 | Geográficas en ED 50
4258 | Geográficas en ETRS89
4326 | Geográficas en WGS 80
23029 | UTM huso 29N en ED50
23030 | UTM huso 30N en ED50
23031 | UTM huso 31N en ED50
25829 | UTM huso 29N en ETRS89
25830 | UTM huso 30N en ETRS89
25831 | UTM huso 31N en ETRS89
32627 | UTM huso 27N en WGS 84
32628 | UTM huso 28N en WGS 84
32629 | UTM huso 29N en WGS 84
32630 | UTM huso 30N en WGS 84
32631 | UTM huso 31N en WGS 84

It is also possible to get all the cadastral references in a square of 50-meters’ side centered in the coordinates `lat` and `lon` through the function `catr_ovc_get_rccoor_distancia()`.

    catr_ovc_get_rccoor_distancia(
      lat = 40.96002,
      lon = -5.663408,
      srs = "4230"
    ) %>%
      knitr::kable()

geo.xcen | geo.ycen | geo.srs | refcat | address | cmun_ine | pc.pc1 | pc.pc2 | dt.loine.cp | dt.loine.cm | dt.lourb.dir.cv | dt.lourb.dir.pnp | ldt | dis
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
-5.663408 | 40.96002 | EPSG:4230 | 5877501TL7357F | AV REYES DE ESPAÑA 1 SALAMANCA (SALAMANCA) | 37274 | 5877501 | TL7357F | 37 | 274 | 643 | 1 | AV REYES DE ESPAÑA 1 SALAMANCA (SALAMANCA) | 21.81
-5.663408 | 40.96002 | EPSG:4230 | 5778706TL7357H | AV REYES DE ESPAÑA 2 N2-4 SALAMANCA (SALAMANCA) | 37274 | 5778706 | TL7357H | 37 | 274 | 643 | 2 | AV REYES DE ESPAÑA 2 N2-4 SALAMANCA (SALAMANCA) | 23.18

## Geocoding a Cadastral Reference

The opposite query is possible as well. Being given to the function `catr_ovc_get_cpmrc()` a cadastral reference (`rc`), the province (`province`) and the town (`municipality`), `catr_ovc_get_cpmrc()` returns its coordinates `lat` and `lon` in a particular `srs` besides the address (town, street and number).

    catr_ovc_get_cpmrc(
      rc = "13077A01800039",
      srs = "4230",
      province = "CIUDAD REAL",
      municipality = "SANTA CRUZ DE MUDELA"
    ) %>%
      knitr::kable()

xcoord | ycoord | refcat | address | pc.pc1 | pc.pc2 | geo.xcen | geo.ycen | geo.srs | ldt
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
-3.456242 | 38.61966 | 13077A01800039 | DS DISEMINADO Polígono 18 Parcela 39 000100200VH67C EL TIRADERO. SANTA CRUZ DE MUDELA (CIUDAD REAL) | 13077A0 | 1800039 | -3.45624183836806 | 38.6196566583596 | EPSG:4230 | DS DISEMINADO Polígono 18 Parcela 39 000100200VH67C EL TIRADERO. SANTA CRUZ DE MUDELA (CIUDAD REAL)

Neither the `province` nor `municipality` are required to be passed to the function, unless the argument `municipality` is not `NULL`, in that case the argument `province` is needed to be passed. If it is passed a value to the `province` argument while the `municipality` argument is `NULL`, the function `catr_ovc_get_cpmrc()` will throw a message and would return a `tibble` with no data.

    catr_ovc_get_cpmrc(
      rc = "13077A01800039",
      municipality = "SANTA CRUZ DE MUDELA"
    ) %>%
      knitr::kable()
    #> Error code: 11. LA PROVINCIA ES OBLIGATORIA

refcat | geo.srs
--- | ---
13077A01800039 | EPSG:4326

When using only `rc` the result is provided as expected:

    # No warning, get the result
    catr_ovc_get_cpmrc(rc = "13077A01800039") %>%
      knitr::kable()

xcoord | ycoord | refcat | address | pc.pc1 | pc.pc2 | geo.xcen | geo.ycen | geo.srs | ldt
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
-3.457532 | 38.61843 | 13077A01800039 | DS DISEMINADO Polígono 18 Parcela 39 000100200VH67C EL TIRADERO. SANTA CRUZ DE MUDELA (CIUDAD REAL) | 13077A0 | 1800039 | -3.45753233627867 | 38.6184314024661 | EPSG:4326 | DS DISEMINADO Polígono 18 Parcela 39 000100200VH67C EL TIRADERO. SANTA CRUZ DE MUDELA (CIUDAD REAL)