[OSGeo Africa] Georeferencing or overlaying old aerial photograph with cadastre

[Chris]

    Hi Aslam , 

    Thanks for the explanation and clarification much appreciated

    Seeing as we are talking historical

    Possibly only of interest to historians of photogrammetry ( and aerial / 
    airforce stuff )

    Were these rigorous processes already being used in WWII  ?
    ( I assume most modern facilities are far advanced beyond these 
    "primitive"  processes )

    Did / does the SAAF have an orthorectification / aerial photography / 
    analysis section ?

    Are they able to perform the same rigorous processes as yourselves ?

    Thanks


    CM




On 17 Nov 2016 at 6:47, Aslam Parker wrote:

> Hi 
 
> Please let me clarify :)
 
> NGI standard orthorectification is a rigorous process that uses high
> resolution aerial imagery, post processed external orientation parameters,
> precise camera models, photo ground control, rigorous bundle block
> adjustment, digital elevation models and individual orthorectification,
> mosaicking, colour balancing and cutting into tiles, and finally
> compression.
 
> When I said we do it all the time, I was referring to numerous requests
> for add-hoc georeferencing of our historical imagery, especially for land
> restitution. As you are aware, our digital orthorimagery only dates back
> to 1990's but we have historical aerial imagery dating back to 1926. In
> this case we often use the rubber sheeting method, but are aware of its
> limitations. We are looking into software that is specifically suited for
> orthorectification of historical imagery using DEM and patch
> rectification.
 
> I trust that this clarifies matters.

 
> -----Original Message-----
> From: Africa [mailto:africa-bounces at lists.osgeo.org] On Behalf Of Chris
> Sent: 17 November 2016 07:20 AM To: Africa local chapter discussions
> Subject: Re: [OSGeo Africa] Georeferencing or overlaying old aerial
> photograph with cadastre
> 
> 
>     Morning Aslam ,
> 
>     Georeferencing by common points
> 
>     I believe you guys ( NGI / SG )  have a more advanced way of doing
>     this whereby one ends up with a proper accurate geo-refeerenced
>     orthophoto ( orthorectified )
> 
>     I am curious ?
> 
>     CM
> 
> 
> 
> On 16 Nov 2016 at 11:06, Aslam Parker wrote:
> 
> > Hi Jeff
> 
> > My colleague Muhammed Deal <Muhammed.Deal at drdlr.gov.za> has a tutorial
> > that he can send you, we do this all the time on QGIS.
> 
> > Please take note that if you do a georeferencing by common points, this
> > amounts to  rubbersheet/transformation and does not create an
> > orthorectified imagery and the georeferencing will be approximate.
> 
> 
> 
> > From: Africa [mailto:africa-bounces at lists.osgeo.org] On Behalf Of Jeff
> > Ngwane Sent: 16 November 2016 12:17 PM To: Africa local chapter
> > discussions Subject: [OSGeo Africa] Georeferencing or overlaying old
> > aerial photograph with cadastre
> 
> > Hi,
> 
> > How to correctly georeference old aerial photograph (i.e 1972) for
> > purpose of being aligned with up to date cadastre on QGIS recent
> > versions? I have been trying but in vain. Please help me.
> 
> > Thank
> 
> > Jeff
> 
> 
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