[jira] [Commented] (JENA-1740) Extending Apache Jena with more geospatial functions
[ https://issues.apache.org/jira/browse/JENA-1740?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=17475146#comment-17475146 ] brain duan commented on JENA-1740: -- cool > Extending Apache Jena with more geospatial functions > > > Key: JENA-1740 > URL: https://issues.apache.org/jira/browse/JENA-1740 > Project: Apache Jena > Issue Type: Improvement >Reporter: Timo Homburg >Priority: Minor > > Hello, > I am the developer of a project which I named postgis-jena > (https://github.com/i3mainz/postgis-jena), originally aimed at extending > JenaARQ with query functions common in databases such as POSTGIS but now > going beyond that approach and also integrating support for raster data > (still WIP). I am building up work being done by Greg Albistons extension > geosparql-jena. > Is this extension of interest for Apache Jena as a plugin or in another > context? -- This message was sent by Atlassian Jira (v8.20.1#820001)
[jira] [Commented] (JENA-1740) Extending Apache Jena with more geospatial functions
[ https://issues.apache.org/jira/browse/JENA-1740?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16918396#comment-16918396 ] Greg Albiston commented on JENA-1740: - Ideally the textual data formats would be treated with a similar approach to the GeometryLiterals. It will depend upon how costly they are to deserialise but should be possible to re-use/re-purpose the current caching for them. > Extending Apache Jena with more geospatial functions > > > Key: JENA-1740 > URL: https://issues.apache.org/jira/browse/JENA-1740 > Project: Apache Jena > Issue Type: Improvement >Reporter: Timo Homburg >Priority: Minor > > Hello, > I am the developer of a project which I named postgis-jena > (https://github.com/i3mainz/postgis-jena), originally aimed at extending > JenaARQ with query functions common in databases such as POSTGIS but now > going beyond that approach and also integrating support for raster data > (still WIP). I am building up work being done by Greg Albistons extension > geosparql-jena. > Is this extension of interest for Apache Jena as a plugin or in another > context? -- This message was sent by Atlassian Jira (v8.3.2#803003)
[jira] [Commented] (JENA-1740) Extending Apache Jena with more geospatial functions
[ https://issues.apache.org/jira/browse/JENA-1740?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16917894#comment-16917894 ] Timo Homburg commented on JENA-1740: I understand. If the literals are accessed that often it might prove not feasible to store the whole image in the triple store. Considering this, I think the hash value would be a good idea. Would you also recommend this for textual raster data formats such as CoverageJSON or GMLCOV or did you only have raster image formats such as GEOTIFF and the likes in mind? I wonder if the textual formats would provide a similar challenge to the triple store if they were to be cached like the GeoSPARQL WKT literals > Extending Apache Jena with more geospatial functions > > > Key: JENA-1740 > URL: https://issues.apache.org/jira/browse/JENA-1740 > Project: Apache Jena > Issue Type: Improvement >Reporter: Timo Homburg >Priority: Minor > > Hello, > I am the developer of a project which I named postgis-jena > (https://github.com/i3mainz/postgis-jena), originally aimed at extending > JenaARQ with query functions common in databases such as POSTGIS but now > going beyond that approach and also integrating support for raster data > (still WIP). I am building up work being done by Greg Albistons extension > geosparql-jena. > Is this extension of interest for Apache Jena as a plugin or in another > context? -- This message was sent by Atlassian Jira (v8.3.2#803003)
[jira] [Commented] (JENA-1740) Extending Apache Jena with more geospatial functions
[ https://issues.apache.org/jira/browse/JENA-1740?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16917512#comment-16917512 ] Greg Albiston commented on JENA-1740: - Additional contributions to the GeoSPARQL extension can be provided through a pull request against the Apache Jena repo on GitHub. A concern with storing large pieces of data in triplestores is that triples can be accessed repeatedly during a query, e.g unbound variables. This means that performance can suffer if the triple cannot be quickly processed and analysed. When developing the GeoSPARQL, I found that the GeometryLiterals were being accessed and decoded about 7 times when resolving a query, hence the short-term caching that is applied. It may be more prudent to use a hashing function, or similar, and store that as the literal value in the triplestore. This can then be used to look up from a filestore and return/manipulate the raster if required. This might mean having a function that converts the hash literal into a raster literal for return from a query. It would seem that a seperate module is needed that can then depend upon the GeoSPARQL module. Within that module the two (or more) groups of functions can be loaded as required by the user. > Extending Apache Jena with more geospatial functions > > > Key: JENA-1740 > URL: https://issues.apache.org/jira/browse/JENA-1740 > Project: Apache Jena > Issue Type: Improvement >Reporter: Timo Homburg >Priority: Minor > > Hello, > I am the developer of a project which I named postgis-jena > (https://github.com/i3mainz/postgis-jena), originally aimed at extending > JenaARQ with query functions common in databases such as POSTGIS but now > going beyond that approach and also integrating support for raster data > (still WIP). I am building up work being done by Greg Albistons extension > geosparql-jena. > Is this extension of interest for Apache Jena as a plugin or in another > context? -- This message was sent by Atlassian Jira (v8.3.2#803003)
[jira] [Commented] (JENA-1740) Extending Apache Jena with more geospatial functions
[ https://issues.apache.org/jira/browse/JENA-1740?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16914324#comment-16914324 ] Timo Homburg commented on JENA-1740: Hello Greg, I agree that the vector data functions could be worth adding. I think it is a question of strategy. I could release a package containing only the vector functions and then have an extended raster package. Would you think this is a good idea? At the same time, I think I can contribute some changes to your geosparql extension which I did in my code. For raster data: In my view the options are like this: # "Convert the raster pixel-by-pixel band-by-band to RDF" - INSANE. Too many triples # Vectorization of the raster: Not optimal as the vectorization might not fit your needs in term of raster size etc. # Integration of the raster image in the triple store as a literal type, a link or a binary blob (RasterWKB - The postgis way) - I would prefer this implementation as it is very flexible, typically people only need a ROI (region of interest) of the raster and often metadata of raster images is rather queried than the image itself. Concerning performance: An interesting question would be in which way the performance of processing of raster deviates from POSTGIS. If federated queries are used and the whole raster needs to be loaded over the internet I would imagine the bottleneck is the download time. Apart from that I currently see no difference concerning the processing speed of the raster processing functions as compared to POSTGIS. (Both may contain rasters in WKB, rasters can be indexed for better performance and annotated, bounding boxes can be extracted to exclude the raster loading for some queries) But I would be interested to know if I am wrong at this assumption. # Lastly: Should the raster be stored in the triple store? I do not know, it could be linked or encoded in a literal. I speculate it would depend on the implementation of the triple store if this has an impact. Also interested to get other opinions on this. Timo > Extending Apache Jena with more geospatial functions > > > Key: JENA-1740 > URL: https://issues.apache.org/jira/browse/JENA-1740 > Project: Apache Jena > Issue Type: Improvement >Reporter: Timo Homburg >Priority: Minor > > Hello, > I am the developer of a project which I named postgis-jena > (https://github.com/i3mainz/postgis-jena), originally aimed at extending > JenaARQ with query functions common in databases such as POSTGIS but now > going beyond that approach and also integrating support for raster data > (still WIP). I am building up work being done by Greg Albistons extension > geosparql-jena. > Is this extension of interest for Apache Jena as a plugin or in another > context? -- This message was sent by Atlassian Jira (v8.3.2#803003)
[jira] [Commented] (JENA-1740) Extending Apache Jena with more geospatial functions
[ https://issues.apache.org/jira/browse/JENA-1740?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16913789#comment-16913789 ] Greg Albiston commented on JENA-1740: - Hi Timo, The work from geosparql-jena is now available as a module in Jena. It should be possible to switch the dependency with only the package names needing updating, i.e. `io.github.galbiston.geosparql_jena` to `org.apache.jena.geosparql`. org.apache.jena jena-geosparql 3.12.0 >From what I recall the PostGIS functions in some cases overlap with the >GeoSPARQL functions, which focuses on spatial relations. This is due to both >in part being derived from the Simple Features standard, but where GeoSPARQL >was designed for open system of SPARQL and PostGIS for closed system of SQL. Something that the PostGIS functions also seem to offer is an extensive range of functions to manipulate geospatial data. The raster data functionality mentioned is not considered in GeoSPARQL. Others might be able to answer better whether raster data is ideally suited for encoding in RDF, storing in a triplestore and querying (doesn't raster data get large very quickly while potentially having a lot of similarity between cases?) or whether some cross-reference lookup to another datastore is needed. Hopefully this a useful and accurate enough generalisation of some differences between GeoSPARQL and PostGIS. Thanks, Greg > Extending Apache Jena with more geospatial functions > > > Key: JENA-1740 > URL: https://issues.apache.org/jira/browse/JENA-1740 > Project: Apache Jena > Issue Type: Improvement >Reporter: Timo Homburg >Priority: Minor > > Hello, > I am the developer of a project which I named postgis-jena > (https://github.com/i3mainz/postgis-jena), originally aimed at extending > JenaARQ with query functions common in databases such as POSTGIS but now > going beyond that approach and also integrating support for raster data > (still WIP). I am building up work being done by Greg Albistons extension > geosparql-jena. > Is this extension of interest for Apache Jena as a plugin or in another > context? -- This message was sent by Atlassian Jira (v8.3.2#803003)
