# Interactive 3D Exploration of RDF Graphs through Semantic Planes
## 3 Use Cases
### Use Case #2: Exploring DBpedia  
DBpedia ([[http://dbpedia.org](http://dbpedia.org)]([http://dbpedia.org](http://dbpedia.org))) is a Public Data Infrastructure for a Large, Multilingual, Semantic Knowledge Graph. As stated in the Introduction, a tool for the visualization of RDF graphs should provide functionalities to declare the portion of the knowledge base that the user intends to inspect. This is particularly true with DBpedia, since visualizing a graph containing 6.6 M entities (as of the last official release dated 2017) can be both heavy and slow to compute and ineffective from the point of view of the results. Thus, the first step when using Tarsier with DBpedia should be the definition of the subgraph of interest through a proper SPARQL CONSTRUCT. In this section, we focus on a specific use case, i.e. retrieving from DBpedia and visualizing the following. _All the artists born in Bologna between 1000 AD and 2000 AD and people who inspired them._  
The desired information can be retrieved from DBpedia with a SPARQL query such as the following:
```
PREFIX:<[[http://dbpedia.org/resource/](http://dbpedia.org/resource/)]([http://dbpedia.org/resource/](http://dbpedia.org/resource/))> PREFIIXxsd:<[[http://www.w3.org/2001/XMLSchema#](http://www.w3.org/2001/XMLSchema#)]([http://www.w3.org/2001/XMLSchema#](http://www.w3.org/2001/XMLSchema#))> PREFIXrdf:<[[http://www.w3.org/1999/02/22-rdf-syntax-ns#](http://www.w3.org/1999/02/22-rdf-syntax-ns#)]([http://www.w3.org/1999/02/22-rdf-syntax-ns#](http://www.w3.org/1999/02/22-rdf-syntax-ns#))> PREFIXfoaf:<[[http://xmlns.com/foaf/0.1/](http://xmlns.com/foaf/0.1/)]([http://xmlns.com/foaf/0.1/](http://xmlns.com/foaf/0.1/))> PREFIXdbo:<[[http://dbpedia.org/ontology/](http://dbpedia.org/ontology/)]([http://dbpedia.org/ontology/](http://dbpedia.org/ontology/))> SELECT?artist?artBirthD?artBirthD?artBirthP?artName?ins?insName?insBirthD?insBirthP?insBirthP?insDeathP WHERE{?artistrdf:typedo:Artist;  rdf:typefoaf:Person;  foaf:name?artName;  dbo:birthDate?artBirthD;  dbo:birthPlace:Bologna. OPTIONAL{?artistdbo:deathDate?artDeathD}. OPTIONAL{?artistdbo:deathPlace?artDeathP}. OPTIONAL{?artistdbo:influencedBy?ins. ?instrdf:typefoaf:Person;  dbo:birthPlace?insBirthP;  dbo:birthDate?insBirthD. OPTIONAL{?insdbo:deathPlace?insDeathP;  dbo:deathDate?insDeathD}. FILTER(?artBirthD>\"1000-01-01\"\"xsd:date). FILTER(?artBirthD<\"2000-01-01\"\"xsd:date) }
```
From the original SPARQL SELECT query, it is possible to design a specific SPARQL CONSTRUCT query to define a graph with the same meaning:
```
```
PREFIX:<[[http://dbpedia.org/resource/](http://dbpedia.org/resource/)]([http://dbpedia.org/resource/](http://dbpedia.org/resource/))> PREFIXxd:<[[http://www.w3.org/2001/XMLSchema#](http://www.w3.org/2001/XMLSchema#)]([http://www.w3.org/2001/XMLSchema#](http://www.w3.org/2001/XMLSchema#))> PREFIXrdf:<[[http://www.w3.org/1999/02/22-rdf-syntax-ns#](http://www.w3.org/1999/02/22-rdf-syntax-ns#)]([http://www.w3.org/1999/02/22-rdf-syntax-ns#](http://www.w3.org/1999/02/22-rdf-syntax-ns#))> PREFIXfoaf:<[[http://xmlns.com/foaf/0.1/](http://xmlns.com/foaf/0.1/)]([http://xmlns.com/foaf/0.1/](http://xmlns.com/foaf/0.1/))> PREFIXdbo:<[[http://dbpedia.org/ontology/](http://dbpedia.org/ontology/)]([http://dbpedia.org/ontology/](http://dbpedia.org/ontology/))> CONSTRUCT{?artistrdf:typedo:Artist; rdf:typefoaf:Person; foaf:name?artName; dbo:birthDate?artBirthD; dbo:birthPlace:Bologna; dbo:deathDate?artDeathD; dbo:deathPlace?artDeathP; dbo:influencedBy?ins.?artDeathPrdf:typedbo:Place. :Bolognardf:typedo:Place. ?insrdf:typefoaf:Person; dbo:birthPlace?insBirthP; dbo:birthDate?insBirthD; dbo:deathPlace?insDeathP; dbo:deathDate?insDeathD.?insDeathPrdf:typedbo:Place.?insBirthPrdf:typedbo:Place. } WHERE{?artistrdf:typedo:Artist; rdf:typefoaf:Person; foaf:name?artName; dbo:birthDate?artBirthD; dbo:birthPlace:Bologna. OPTIONAL{?artistdbo:deathDate?artDeathD }. OPTIONAL{?artistdbo:deathPlace?artDeathP }. OPTIONAL{?artistdbo:influencedBy?ins. ?instrdf:typefoaf:Person; dbo:birthPlace?insBirthP; dbo:birthDate?insBirthD.