On Thu, 10 Jan 2019 at 20:57, Michael Patrick <[email protected]> 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 :-() Thanks Graeme
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