Overview

To improve the interoperability of geospatial data in the IIIF Georeference Viewer, we added support for data structures conforming to the Linked Places Format (LPF). This article explains the overview of LPF and the implementation details.

What is Linked Places Format (LPF)?

Linked Places Format is an interoperability format for gazetteer data developed by the Pelagios Network. It extends GeoJSON and incorporates Linked Data (JSON-LD) concepts, enabling sharing and linking of place information across different datasets.

Features of LPF

  1. JSON-LD compatible: Supports the Semantic Web using @id and @context
  2. GeoJSON extension: Adds metadata while maintaining standard GeoJSON structure
  3. Link functionality: Expresses references to external datasets using links arrays
  4. Temporal information: Describes temporal information through the when property

Official Specification

Comparison with Previous Format

Previous Format (metadata object)

{}""}"}"}tp,g,myr"e""e"""""porotctiltuxepemyoadaary"esepod"bglw:rotera:es"htur"dtl":""iry:ia""::Fec"n"h:"ese:"a:t[h"a"CPtt""t5t:o{oe{p電工t9uois:気学p3r{rn"/実部s6edt:/験":,"s"e室]/6,",[x",/3:1a,m43ma4[9pp,6.ls967e.796.a602op,,3rp11g.378/g852po41,lo"7a.]3cg5el.//71d12J53d1"X2,X3Q3E]A8dWSptgt8",

The previous format stored all metadata within the metadata object. While simple, it had the following issues:

  • Low interoperability with other tools due to non-standard format
  • Difficult to use as Linked Data
  • Unable to express the type of links to external resources (same, similar, etc.)
{}"""}"]"}t@p,l,gyir""""i{}{}e""pdorttxn,otce"peiayk""""myo":estgwstitiepo:rolsh"ydydter"tue"":peper"d"hir"::eneny:iFtec:["t"t"netse[":i:i:"aap"C""5ffPtts:o電工9"i"i{oeu:o気学3peceisr/{r実部6rrlrn"e/d験",i"o"t:"es室]6m:s:",x"",3ae,[a:,4r"M"1m4yhah3p[,Tttt9l69otct.e67pphp7.96is":6o0,c:,/2r,1O//3g3f/w1/78"mw8p54,aw2l1"p.,a7swc].i3e,ak5spi./pd7d.a1egt5noa1ko.2i.o3-gr3jlg]i//kdekJnedtnXisXthQyiE/tAQs81ud2"W3,S4p5t6g"t8"

Format Design Details

Placement of @id

GeoJSON standard (RFC 7946) and Linked Places Format differ in where identifiers are placed:

FormatKeyLocationPurpose
GeoJSON standardidDirectly under FeatureSimple ID within a file
Linked Places Format@idDirectly under FeatureURI identifier for RDF/Linked Data

Checking the official LPF samples, @id is placed directly under Feature:

{}"""]t@fyce{}poaent"""}""tu@tp,l:eriyr"ixedpotn"ts"epikF"":"etse:::rl"a"te:t"[h"i"uhtFe:[rttes.etpa"".Cp:t:A.os/ub]l:/r{il/mene/y"gcrg,dtaaoiwzno..ngo("irU,tgKh/)up"bluasceersc/opn_t1e2n3t4.5c"o,m/LinkedPasts/linked-places/master/linkedplaces-context-v1.1.jsonld",

Placement of title

In LPF, title is placed within properties. This design ensures that information is retained as attribute data when loaded in GIS software (such as QGIS).

links is placed directly under Feature and expresses references to external resources. Each link has a type and identifier:

"]li{{{{n""""kttttsyyyy"pppp:eeee""""[::::""""ecpsxlreaoiecsmAtealMMrsaayottT"cco,hhp""i",,ciOd""feii"ndd,teeinn"fttiiiidefferiin"eet:rri""f"::ihet""rthh"ptt:stt:pp"/::h//te/txspaoosmcm:pae/lbg/e.ae.gznoe..rtowgtri/ygkr./ieeppldleauadt/cieteadgs."no}3r79g08/14w17i9"k4}i4,/".}.,."},
TypeDescriptionExample Usage
exactMatchIdentical resourceGetty TGN, GeoNames
closeMatchSimilar resourceOther gazetteers
primaryTopicOfWeb page about this placeWikipedia, Google Maps
subjectOfDocument mentioning this placeHistorical documents
seeAlsoRelated resourceRelated information

Implementation Details

Type Definition Updates

i}i}nnttit["lp}g}m}ceydex@ir;e;e;orper:inorttx[otctiltux[mfenfRdRkpeiaykmyoLadaarykpa:tase"esestgweepoed?bglweocictc?c?roRlshyterga:es?hysesfero:o:tuee??:r:datl?:?:atiimmirc?::yicas?::bFreFnmsmFeco:s:sny?t:ssleiregeteesemsstta::rststean:a]nrna:Cmsttr{rtistrtrstgt:didtoetrriiem{ntriri/u;sueneu{onriinnsegrininurtradgdrrdinngg:t;ingngseren:;:edengg];ang;g]eLiyLsdg[;:ndg[;:Sin{;@li::;]ua;]enegiin;amt;atk.;dnknmnbantgk[ueyeyi{.as]mt;ro;n,t;ba[bgaed]js"ttra[e.co[t]ctlpt]a;tsoo;slpi(eensMvltaeepitlvrlceolh(lp"Les,i(runLtp"kiippeneordksrietmPdealdraPyclfTeaooscrpeiFsbcoaOrFcfmok"arw,tmaar"/tde)sxJaSccOotNmM-paLatDtcihcb"oimlpiattyi)ble)

ID Resolution Priority

To support both old and new formats, IDs are resolved in the following priority:

ci}i}offni}}fcIs(fl(eoDt!fefa!amのf(elebftp優pepasaeeuo先rartetlars順eteuuのtea位dudr{r優u.b:ereee先rllfef..順eae@i.iii位.bsinindd:le/dedealud)d==pbs(IIre=eLd{dp`olDP)rfp)fiF=eeees){dar{apfetttl>efuiuaaireryitnese.due_..trd$tps(eI{irG[ditoe";tlpo@eeeJimrSdI(tO"n推iN]d奨e)e)sx?>>.+tpfmire1etoa}tlpt_aeeu$drr{atefti.eaeia.fsdtle.uaairbtdeeuIlr>fneed(.maeレmetxガetuシtar+ーade)da.1atp}tar`a.o;?ip.delra>tbie自el動s生?成.id"";feature.metadata?.id;
cccccccli}}ooooefnnnnnnntlelc新ssIststslssl(i.lioフttDtitatittildn`jsnmォ:tgnniik<oekpーmpdldsdkdlknssaisoマer@iei:isieskpHniHnッtois:ss:sgのsltt(fteトapdpppppa表Hama'mndslplrlflc示tylr(lt(a(araoaeayをmLglsLt=LyoypyayU生li=ee=/PaPIpTeTtLr成ntgpFfFdeirauil=kd=)a`a/=e)rttgrnsi";c<npa=tlisek=.s_yaerft>iee.s'lpbUseufes=lm;ellrtparies=.i=enaalaMeteda.tpntgyn)raru.ttparkfatLkgptrp(uirgosedhi"{e.ierGrtospaantve.oeelps(tt>kh=usmpo[es(.Luasr"e)eeJ".推tPr.0.e_trS@(t奨aFeu)mfbとatOi推i)g).ra=l旧diNd奨tsll{p"aフae)")l>>i;($nォts]en({kーa>>mmkll"マeesiiッmmtmtnnhトeeaeakkr{tftmdtd:.e({}aeaeaaaifm};dadttdt[ad=e;ataaaaa]ne"ttutd.t.;yn$aaraatau)t{d.e.ta.rilai.lagtl=fetdia.sa>igadblg(ea)(ea(sレrcレlbレ;ガ}yのガeガシ"U両シ(lシー>r方ーmレ;ー)$lを)eガ){}サtシl"ポaーi>ーd)n$トak{t.tat(.y"ipddee;}t<a/ial>"`)}</a>`;

GeoJSON Conversion for MapGL

c}o)ncccccccr};csoooe;otnnnnnnnttp}g}mssIststslsusuyr,epgttDtitatitrtrpoiltluotcoe:tgnlnepdaairmyonompdldsdkd:l:e:bgnlepoejer@iei:isie{resk:ternstois:ss:smg'tdl:sr:dtoapdpppppeaFii::lyisndslplrlfltceesde:'n/Fa(araoaeaayaspdidgPapet=LyoypyaydUt:lisia{otaaaPIpTeTtLaruaspscientfFdeirauitlr{yplpynseu=e)rttgrnaeIlalUt:sra=tlisek.='dayar'/eft>iee.su,,yTyl,[Mseufes=lrmTaLfaaries=.i=leigiep=teda.tpnttsnaGu.ttparkf(al,ktLfrp(uirgoseレdesu.eerGrtospaガa,,rva.oeelps(tシteutmpo[es(.Luーa.eueeJ".推tPr).grtrS@(t奨aFeueeatOi推i)g).rosdiNd奨tsllm.ae)")l>iemts]entaa>>mkrpesymmtm?eeae'.f{tftmdt;ce{}aeaeaaoa};dadttd[ot;ataaaa]rututd.t;draraataie.e.ta.n:i.lagtadia.satadblgen(ea(ssyレlbレ?)ガeガ.シ(lシ[=ーmレー0>)eガ[]tシ]{aー;d)a't;0a,.ifde;ature.geometry?.coordinates?.[1]0]

Backward Compatibility

To avoid breaking existing data, the legacy metadata object format continues to be supported. Even when old and new formats are mixed, everything works correctly:

{}""]tfye{}{}pa,et"""}""""""}"ut@p,lgtpgm:ryir""ieyree""epdortnopootlu"se"peikmepmaarF"":estse"eedble::rol"t:rtae"a"tue:rtrtl:t["hir"y"iya"uFtec:["Fe"":"retse{:es::heap"C""a""tCts:o新t{t:{{旧tou:oフy"u"フplr/{rォptr{tォsle/dーeye"yー:e"esマ"p"rpマ/c,x"ッ:e,eeッ/ta:ト"s"ト.imの":o:の.op[例pu例.nl1"r"r""""e0iPcP,,.0moeoo,aiCirrnong2ytot/0T"r"p0o,d,l]psa,i"""ccc:ceOoosfo[o/"r3rn,d0dei0iw"n,n-iaafdt4toee0erns0smt"]"ai:}:tf,"i[[,e11r34"90:..00",,ht33t56p..s00:]]/}}/,..."}],

Benefits of Adopting LPF

1. Improved Interoperability

LPF is designed for data exchange between gazetteers. It facilitates integration with projects such as:

2. Linked Data Support

By using @id, each place can be uniquely identified by URI and utilized as Linked Data. This enables:

  • Easy conversion to RDF
  • Querying via SPARQL
  • Integration into the Semantic Web

The links array allows explicit expression of relationships with external resources:

  • exactMatch: “This place is identical to this entry in Getty TGN”
  • closeMatch: “This place is similar to this Wikidata entity”
  • primaryTopicOf: “For this place, refer to this Wikipedia article”

4. GIS Tool Compatibility

By placing title and tags within properties, they are displayed as attribute tables when loaded in GIS tools like QGIS.

Future Outlook

Temporal Information Support

LPF allows describing temporal information through the when property:

{}""}"}@p,wir"h"]dotet"pini{:et"m"rl:es"testhi"{pate:artsntp""s"::旧":/本:/{館{e"["xianm"p:le".1o8r7g7/"p}l,ac"eesn/do"l:d-{b"uiinl"d:in"g1"9,23"}}

In the future, we are considering adding timeline display features utilizing this temporal information.

FeatureCollection-level @context

For full LPF support, we plan to support @context specification at the FeatureCollection level:

{}"""}"]"}t@p,l,gyir""""i{}{}e""pdorttxn,otce"peiayk""""myo":estgwstitiepo:rolsh"ydydter"tue"":peper"d"hir"::eneny:iFtec:["t"t"netse[":i:i:"aap"C""5ffPtts:o電工9"i"i{oeu:o気学3peceisr/{r実部6rrlrn"e/d験",i"o"t:"es室]6m:s:",x"",3ae,[a:,4r"M"1m4yhah3p[,Tttt9l69otct.e67pphp7.96is":6o0,c:,/2r,1O//3g3f/w1/78"mw8p54,aw2l1"p.,a7swc].i3e,ak5spi./pd7d.a1egt5noa1ko.2i.o3-gr3jlg]i//kdekJnedtnXisXthQyiE/tAQs81ud2"W3,S4p5t6g"t8"

0

Summary

By adopting Linked Places Format, the IIIF Georeference Viewer has significantly improved the interoperability of geospatial data. While maintaining backward compatibility with existing data, incorporating Linked Data concepts enables richer metadata representation and integration with external resources.

We hope this will facilitate sharing and referencing place information across different datasets in historical geography research and digital archive projects.

References