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

[Zoltan]

Hi Jeff,
You might want to google "how to orthorectify an aerial photo" so that 
you begin to understand the enormity on both the task and the 
information needed, for "How to correctly georeference...." an image.
That is why I asked you the type of terrain (flat or not) in my first 
response.
Reading the other responses, and assuming that it is mostly for visual 
use, rubber-sheeting is your simplest method - even if tedious. You're 
not going to get great results if the terrain is mountainous.

Hope you don't have too many images......

Regards,
Zoltan


On 2016/11/17 09:56, Jeff Ngwane wrote:
>
> Thank you very much for responses.
>
> I am ok with the output because I use raster georeferencing for 
> display purposes and will be done in conjunction with latest satellite 
> image.  Actually, I got GCPs from Google Earth image. The problem is 
> when georeferenced image get loaded up on QGIS it does not align with 
> cadastre. I do not have a problem with topographic maps as they do 
> align; same applies to satellite images with map projection (old and 
> new). My main challenge is with historical aerial photo maps from NGI. 
> I only received images (jpeg) and flight plans from NGI with no .tfw 
> file and struggling.
>
> With Thanks
>
> Jeff
>
> On 17 November 2016 at 08:47, Aslam Parker <Aslam.Parker at drdlr.gov.za 
> <mailto:Aslam.Parker at drdlr.gov.za>> 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
>     <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
>     <mailto: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
>     <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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-- 

===========================================
Zoltan Szecsei PrGISc [PGP0031]
Geograph (Pty) Ltd.
GIS and Photogrammetric Services

P.O. Box 7, Muizenberg 7950, South Africa.

Mobile: +27-83-6004028
Fax:    +27-86-6115323     www.geograph.co.za
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