[OHM] OHM's purpose and differences with regular OSM

[Carlos Cámara]

I have recently discovered OHM and, whereas I understand the importance of
displaying historical data and I acknowledge the importance of a
crowdsorced approach like OSM, it is not clear to me how does OHM work and
how it differs from regular OSM. As far as I know, the username, tagging
system and even software (at least JOSM), work with OHM, but apparently,
the database and infrastructure are completely different.

To make things more confusing, since I haven't seen any timeline or slider,
I am wondering if the displayed data has to be focused on a specific period
of time or not. That would explain the fact that I zoomed in some areas
like Rome or Egypt which potentially may have historical data due to their
long history, but could not see any data on the map.

Regards,

Carlos Cámara
http://carloscamara.es

[Warin]

Post by Carlos Cámara
I have recently discovered OHM and, whereas I understand the
importance of displaying historical data and I acknowledge the
importance of a crowdsorced approach like OSM, it is not clear to me
how does OHM work and how it differs from regular OSM. As far as I
know, the username, tagging system and even software (at least JOSM),
work with OHM,

OSM does not recored what is no loner there. Sau an old railway that has
been changed into house. It simple is no longer there so it does not go
into OSM. In OHM is can exist.

Post by Carlos Cámara
but apparently, the database and infrastructure are completely different.

The data base can use OSM as the present, but it would be a duplication.
But can also have information about things that existed in the past.

The additional thing to having OHM are the start and finish dates so OHM
then know at what time period these things existed.

Post by Carlos Cámara
To make things more confusing, since I haven't seen any timeline or
slider, I am wondering if the displayed data has to be focused on a
specific period of time or not. That would explain the fact that I
zoomed in some areas like Rome or Egypt which potentially may have
historical data due to their long history, but could not see any data
on the map.

[PauLL170]

Hi,

you can map whatever you want: any historical objects and also existing
objects, since they exist since a certain time. Of course there are
different "strategies": Some people focus on certain objects (there used to
be a project to map the major roman roads), some people focus on the
complete history of one place including today's objects etc.
The tagging system is indeed identical with OSM. A time slider is still
missing, but as I heard, it is in development. Please remember to add
start_date (and end_date) tags, even if you don't know exact dates (see
https://wiki.openstreetmap.org/wiki/Open_Historical_Map#Tagging). The time
slider will retrieve these tags.

Best regards,
Paul