[OHM] OHM data model - can it be changed? Re: Thesis about Open Historical Map

Mon Feb 4 15:29:00 UTC 2019

Hello Jeff,
thank you very much for the OHM insights.

As you know, we play around with a similar project
since 2015.

https://github.com/OpenHistoricalDataMap

We learned a big deal about working with huge
data but also how GeoSPARQL could be used as bridge
into the wonderful world of Linked Open Data.

As I could see, that is also project of OHM.

To make things short: I wonder, if you have any plans
to change the OHM data model?

In my eyes, there is one crucial problem:

OSM does not separate between objects and their geometry.
In OSM, that causes no problem - in OHM it will.

I'm sure, you are aware of that issue: Objects can change.
A trail can become a highway and vice versa. A fortress can
be extended or partly destroyed. The object is not changed
in any case but its features or geometry.

We have split both concepts (object and geometry) in our project.

https://github.com/OpenHistoricalDataMap/OHDM-Documentation/wiki/OHDM-Data-Model

https://www.researchgate.net/publication/303818952_Open_Historical_Data_Map_OHDM_-_work_in_progress

My office is in a building that used to be a factory a decade ago.
Geometry hasn't changed. Feature set has.

There are start_day and end_day tags in OHM. OHM would need a *copy*
of the geometry to model my office and the previous factory building,
though.

Each OHM object would have it own id and the apparent relation
between both would get lost. (Not to mention the wast of memory space) 
That's a real pity when it comes to semantic relations like LOD. A
time line, a changing object in time is is of major interest in
systems like OHM. That relation would get lost because each point
in time would be represented by another OHM ID.

Did I understand something wrong?

I see two solutions:

1) The OHM model is to be changed in a way that this n-m
relation is made explicit.

Drawback: It would become incompatible with OSM. That
is a huge drawback.

2) An OHM 2.0 database is produced. That database works with
a changed data model but can produce the OHM format as usual.

Actually, that is what I would like to do with our OHDM project:
Using our data model but drop all efforts for building editors
etc. We would ex- and import OHM data. But we could attach to
our data model with e.g. Parliament
(http://parliament.semwebcentral.org/) to offer a LOD source.

I just wonder if you plan to tackle that issue.

Best regards,
Thomas

PS: Have I mentioned that I still love strolling through
old maps. I really like the idea having a running OHM full
of data :)

Am 29.12.2018 um 18:21 schrieb Jeff Meyer:
> Hello Volkan!!
> 
> Thanks for your great questions! It's very exciting to know there are 
> others working on similar / helpful projects.
> 
> First, there are a few things we're working on for OHM that will make 
> the future OHM slightly different from what's available today. I'll try 
> to distinguish between the two where appropriate. Hopefully, this won't 
> be too confusing.
> 
> 1. What are the exact goals of OHM ? Which of these have already been 
> implemented ? Which functionalities are planned for OHM ?
> The goals of OHM are:
> a. Create a cool online time machine where people can come and view 
> depictions of high- and low-level geographic information (maps!) 
> throughout history.
> b. Create a common, open, shared repository for vector-based map 
> information that users can improve.
> c. I'm sure there are other goals and purposes that others on this list 
> might add.
> 
> 2. Which functionalities have already been implemented ?
> Because we are borrowing most/much of our technology from OpenStreetMap 
> (OSM), almost anything OSM has implemented we can currently use.
> These include:
> - Map database
> - Raster tile service for rendering maps
> - API for import / export
> - Editing tools, both in-browser and external
> 
> 3. Is there a way to get the map data, like an API ?
> Yes, a very basic API that takes a geo bounding box for both reading and 
> writing to the central database.
> 
> 4. Can I import maps in OHM ?
> Certainly, although you may need to convert your GIS files into OSM 
> formats and we ask that there be start_date and end_date and source tags 
> added to all your ways.
> 
> 5. Can I filter the map for a specific year, like I would like to see a 
> map from 1907, if not, will this functionality implemented soon ?
> Yes! Sometime in early 2019, we hope to make this more widely available, 
> but an early prototype is available here:
> https://openhistoricalmap.github.io/openhistoricaltiles/datefilter/#14.00/40.78411/-119.21285/2008-08-15,2008-09-15/
> 
> 6. What does the data model of OHM look like ?
> We use the OSM data model, which you can learn more about at the OSM 
> wiki, but it loosely consists of basic GIS data types that have 
> associated key:value pairs.
> 
> 7. How far is the development of OHM (in percent) ?
> Hard to say & it depends on whether you'd include what OSM has already 
> built into that estimate. Regardless, we have a fair amount of 
> customization we'd like to do.
> What are your specific needs?
> 
> Thanks,
> Jeff
> 
> 
> 
> On Thu, Dec 27, 2018 at 8:40 AM "Volkan Özgen" <volkan.oezgen at web.de 
> <mailto:volkan.oezgen at web.de>> wrote:
> 
>     Hello Open Historical Mapper :),
>     my name is Volkan, I'm from Berlin, Germany and I currently study
>     applied computer science at HTW-Berlin (Hochschule für Technik und
>     Wirtschaft).
>     I'm currently working on my thesis and the title is "Usability of
>     Open Historical Map for Open Historical Data Map".
>     Open Historical Data Map is like OHM a open source project by Prof.
>     Dr. Thomas Schwotzer. He is my professor at the university.
>     The goal of OHDM is to create historical maps.
>     There are a few things I need to know about OHM for my thesis:
>       1. What are the exact goals of OHM ? Which of these have already
>     been implemented ? Which functionalities are planned for OHM ?
>       2. Which functionalities have already been implemented ?
>     3. Is there a way to get the map data, like an API ?
>       4. Can I import maps in OHM ?
>       5. Can I filter the map for a specific year, like I would like to
>     see a map from 1907, if not, will this functionality implemented soon ?
>       6. What does the data model of OHM look like ?
>       7. How far is the development of OHM (in percent) ?
>     I know that's a lot of questions but I hope you guys can help me out :)
>     Wish you all a great day and merry christmas :)
>     Greetings from Germany
>     _______________________________________________
>     Historic mailing list
>     Historic at openstreetmap.org <mailto:Historic at openstreetmap.org>
>     https://lists.openstreetmap.org/listinfo/historic
> 
> 
> 
> -- 
> Jeff Meyer
> 206-676-2347
> osm: Open Historical Map (OHM) 
> <http://wiki.openstreetmap.org/wiki/Open_Historical_Map> / my OSM user 
> page <http://www.openstreetmap.org/user/jeffmeyer>
> t: @OpenHistMap
> 
> 
> 
> 
> 
> _______________________________________________
> Historic mailing list
> Historic at openstreetmap.org
> https://lists.openstreetmap.org/listinfo/historic
> 

-- 
Prof. Dr.-Ing. Thomas Schwotzer
Hochschule für Technik und Wirtschaft (HTW) Berlin
University of Applied Sciences
FB 4 | Angewandte Informatik | WH C 616
Wilhelminenhofstraße 75A, 12459 Berlin
Phone +49 30 5019-2604 | Fax +49 30 5019-482604
Thomas.Schwotzer at htw-berlin.de | www.htw-berlin.de