[OSM-dev] [OSM-talk] Assembling imagery: to mosaic or not

Christoph Hormann chris_hormann at gmx.de
Sat Jan 4 08:48:53 UTC 2014


On Friday 03 January 2014, Paul Norman wrote:
> [...] The
> two options are to add a number of discrete sources, or to add a
> layer mosaicking them together, and displaying what the best source
> is at any one point.

I think this is the primary issue you need to consider.  If you are sure 
you know what the 'best source' is at any point (which in the most 
general case requires in depth knowledge of the area and of the image 
data in question) mosaicking might be the best solution (but can be a 
real lot of work).

If on the other hand you plan to just layer the image sources by formal 
quality measures (like resolution and age) to create the mosaic you 
will most likely end up with less than optimal quality in some areas.

In addition there is of course a significant value of having multiple 
images available in itself since it allows the mapper to get an idea on 
how variable images can be.  A frequent mistake in common practice 
armchair mapping is that people regard the image as the truth rather 
than a most likely inaccurate depiction of the truth.  Having several 
images available can help here.

-- 
Christoph Hormann
http://www.imagico.de/



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