[Tagging] Quick Building tracing question...

Graeme Fitzpatrick graemefitz1 at gmail.com
Fri Jan 11 00:34:40 UTC 2019

On Thu, 10 Jan 2019 at 20:57, Michael Patrick <geodesy99 at gmail.com> wrote:

> Actually, you can, especially if you have imagery from multiple platforms
> at different times of year, or better yet, different times of day.
> Shadows are usually the primary clue. Partial obstruction of other objects
> in the scene is another - like a semi-trailer truck poking out of a roof.
> Pavement staining and tire marks from fork lifts. slopes of piles of
> material along walls. Footpaths in snow., or if snow accumulates on the
> roof. Stacked containers. If you have evening or night imagery, the light
> silhouettes cast through windows to the outside. The presence of HVAC
> equipment and ducting on the roof, and roof materials in general.
> Obscuration or disturbance / distortion of vapor plumes from vehicle
> exhaust or furnaces.
> All this falls under 'aerial photointerpretation'. The ones I mentioned
> above were from a WW II military training manual, some of the 'key' guides
> now are thousands of pages long.

Thanks Michael - you must access to much better aerial imagery than we do!
- it's sometimes hard to even make out the actual outline of the building,
let alone heat blooms! :-)

Seriously though (& not arguing :-)), "a semi-trailer truck poking out of a
roof. Pavement staining and tire marks from fork lifts" wouldn't really be
enough to say definitely whether you're looking at a roof over an open area
or an enclosed building, would it? That truck could be poked out of the
doors of an enclosed loading dock, & the forklift could be doing the same?

Yes, if you've got slanting or night time imagery that may help, but I've
never seen it in the areas I map in :-(

On the subject of clarity of images. Was mapping the other day (using iD),
marking buildings in an industrial area. As I said, the photo's weren't the
clearest, but I was also peering through the purple haze of the mapped
area=industrial, which certainly doesn't help matters either :-(

Does anyone know of any way of making that disappear / clear away (apart
from deleting the area, & re-creating it after doing the buildings etc,
which is a hell of a lot of work :-()


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