[Talk-GB] Poly Tunnels vs Greenhouses

[Mark Goodge]

On 08/11/2019 20:50, Philip Barnes wrote:
> No problem with boats and greenhouses that don't move.
> 
> But these are probably seasonal and certainly shouldn't be mapped
> from aerial imagery alone as they may have long gone. They certainly
> need a recent survey.

I don't think polytunnels in open fields should be mapped, for this 
reason. They are seasonal and transient. They will be there for part of 
the year, and then removed after the growing season, and may not be used 
again on the same field the following year.

However, there are some permanent polytunnels that are, effectively, 
plastic greenhouses. Those can, and should, be mapped. But it needs 
local knowledge to map them. You can't do it from imagery.

> It reminds me of the time an armchair mapper carefully traced a Maize
> Maze that had existed for a short time in a field near me a couple of
> years earlier.

I'm pleased to see that we do have the Hampton Court Maze mapped, though :-)

Mark