ISO 19156 terms in situ & ex situ

[PeterParslow]

The definitions (& examples) for these two terms seem to be the normal use (e.g. in geology and biology).

But in the ISO 19176-1 Analysis Ready Data / OGC ARD SWG it has become clear that some domains use the term "in situ" with different meanings - but could otherwise make use of ISO 19156 OMS.

Specifically, it I've understood him right Peter Strobl (European Commission, speaking from a CEOS perspective) considers "in situ" to mean that the sensor is (relatively) near the thing being observed. So in that domain, an observation from a satellite is not "in situ" even thought the thing being observed is in its natural surroundings.

Another person in OGC ARD SWG spoke from an oceanography background where they allow an observation to be considered "in situ" even if the sample has been taken from the environment but the sensor is then immersed in the sample (and they have confidence that the phenomenon being observed has not been effected - so chemistry of the water, but not the temperature).

So in geology, biology, and OMS, "in situ" means that the thing being observed is in its natural place - the sensor may be any distance away. But in EO & oceanology, the thing being observed may have been removed, but the sensor must be near or in the sample.

[ReesePlews]

@PeterParslow thank you for mentioning this. TMG has yet to see the 19176-1 document for processing and review comments. 19156-1 defines ex situ and i_n situ_ . 19159-1 defines in situ measurement. presently no other standards use the terms. i look forward to seeing the draft of 19176-1.

[PeterParslow]

ISO 19176-1 may not use the terms. It's simply the place in which we realised that the ISO 19156 definition is in common use in some domains but has different definitions in common use in two other domains.