SJ: Oftentimes we all have to guess with your postings and continously ask that you provide proper context.
There are very few hits or information, but I can only assume that: 1) The text is from Australia?; and 2) it appears that the term you seek refers to "easement view" rather than just "easement camera"; 3) Your guess would be as good as mine as to what it really means, as I have no idea, and may well be quite country-specific in terms of its meaning!

It would really help if you would identify the source country in your postings, that being but one suggestion re additional context.


‘Easement View’ cameras
https://webcache.googleusercontent.com/search?q=cache:iF6t-U...
Sydney Trains Engineering Manual – Common Civil and Track Technical Maintenance
Page 35


Normal Day Light Conditions
If one of the ‘Easement View’ cameras has failed, and there is a satisfactory ‘Easement
View’ camera image (either Front or Rear), then the standard review can be undertaken
using the alternative imagery.
Tunnels and Low Light Areas (Infrared Cameras)
If one of the ‘Infrared Easement View’ cameras has failed, and there is satisfactory
‘Infrared Easement View’ camera image (either Front or Rear), then the standard review
can be undertaken using alternative imagery.
Note: Upon commencement of using the Infrared Imagery system the Front Easement
view will be darker due to less lighting. It is only permissible to use this camera imagery in
this failure scenario for a maximum of 1 week in a row. Once equal light has been
achieved on both cameras this requirement does not apply.

As I said above, this term has a special meaning in railway jargon — just as in road layouts, we can talk about 'easing a bend'.
Here is a reference that explains what it is — though please not, they are talking specifically about 'easement curves' here, i.e. not in the more general sense I have been referring to above; they fail to highlight the point that using 'easement curves' is necessary in order to avoid carriages 'swinging out' too far as they enter or leave a curved stretch.

http://www.sumidacrossing.org/ModelTrains/TrackandRoadbed/Fl...

The development of rail trails in southeastern Australia can be traced to the gold rushes of the second half of the 19th century. Dozens of rail lines sprang up, aided by the overly enthusiastic "Octopus Act", but soon became unprofitable as the gold ran out, leading to a decreased demand for timber in turn. Decades later, these easements found a new use as tourist drawcards, once converted to rail trails. Dozens exist in some form, like the 37-kilometre (23 mi) Port Fairy to Warrnambool Rail Trail,[21] but only a few — such as the 95-kilometre (59 mi) Murray to the Mountains Rail Trail — have been fully developed. Progress is frequently hampered by trestle bridges in unsafe condition, easements that have been sold off to farmers, and lack of funds.
...
Rail trail conversions can be complex for legal, social, and economic reasons.[citation needed] Railroads in North America were often built with a mix of purchased land, government land grants, and easements. The land deeds can be over a hundred years old, land grants might be conditional upon continuous operation of the line, and easements may have expired, all expensive and difficult issues to determine at law.
...

A railroad right-of-way (easement) width varies based on the terrain, with a 100 feet (30 m) width being ample enough where little surface grading is required.[40] The initial 705 miles (1,135 km) stretch of the Illinois Central Railroad is the most liberal in the world with a width of 200 feet (61 m) along the whole length of the line.

https://en.wikipedia.org/wiki/Rail_trail



A right-of-way (ROW) is a right to make a way over a piece of land, usually to and from another piece of land. A right of way is a type of easement granted or reserved over the land for transportation purposes, such as a highway, public footpath, rail transport, canal, as well as electrical transmission lines, oil and gas pipelines.[1] A right-of-way can be used to build a bike trail. A right-of-way is reserved for the purposes of maintenance or expansion of existing services with the right-of-way. In the case of an easement, it may revert to its original owners if the facility is abandoned. ****This American English term is also used to denote the land itself.****

https://en.wikipedia.org/wiki/Right-of-way_(transportation)

here

"easement" is used as another name for the narrower LEGAL concept of "right-of-way (ROW)"

As cameras (be it in the visible light or infrared) can not take pictures of legal concepts, in this text

"easement" / "right-of-way" is used as another name for THE LAND over which the railway company has a "right-of-way".








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Note added at 3 hrs (2021-08-21 15:44:55 GMT)
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in plain speak: these cameras take pictures of the whole strip of land dedicated to the rail track: the space between the rails and 2 or 3 meters on each side.

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Note added at 3 hrs (2021-08-21 15:57:05 GMT)
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These "diagnostic/inspection" cameras keep recording as the train moves along "the easement".

ONLY when there is not enough visible light (like in a tunnel) infrared cameras are used.

"the easement" refers to ANY PART of the rail track, not only to tunnels.